What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No. 7. The thermostat/programmer in the hallway was only rarely set to
above 18C. Only on the very coldest days of winter would we have to put
it up to about 20 or 21C.

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that
was set at the factory or if the installers set it.

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know it never had a frostat connected - unless it was factory-fitted
and integral to the boiler itself but definitely no external unit was
wired in.

The new installation *does* have a (Honeywell) frostat wired in and
it's keeping the heating on all night, irrespective of if I turn the
hallway stat/programmer down to a very low level or completely off.
This is really bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to *any* form of heating on at night and it's making it difficult to
sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

In article ,
Cliff Topp wrote:
What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No. 7. The thermostat/programmer in the hallway was only rarely set to
above 18C. Only on the very coldest days of winter would we have to put
it up to about 20 or 21C.

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that
was set at the factory or if the installers set it.

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know it never had a frostat connected - unless it was factory-fitted
and integral to the boiler itself but definitely no external unit was
wired in.

The new installation *does* have a (Honeywell) frostat wired in and
it's keeping the heating on all night, irrespective of if I turn the
hallway stat/programmer down to a very low level or completely off.
This is really bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to *any* form of heating on at night and it's making it difficult to
sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Change the setting on the froststat so that it comes on at a lower
temperature.

I'm not sure if your pont 1 is true, The boiler doesn't need to work so
hard first thing in the morning if the house is moderately warm when it is
told to heat the house.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On Saturday, 2 January 2021 at 17:46:15 UTC, charles wrote:
In article ,
Cliff Topp wrote:
What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No. 7. The thermostat/programmer in the hallway was only rarely set to
above 18C. Only on the very coldest days of winter would we have to put
it up to about 20 or 21C.

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that
was set at the factory or if the installers set it.

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know it never had a frostat connected - unless it was factory-fitted
and integral to the boiler itself but definitely no external unit was
wired in.

The new installation *does* have a (Honeywell) frostat wired in and
it's keeping the heating on all night, irrespective of if I turn the
hallway stat/programmer down to a very low level or completely off.
This is really bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to *any* form of heating on at night and it's making it difficult to
sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?
Change the setting on the froststat so that it comes on at a lower
temperature.

I'm not sure if your pont 1 is true, The boiler doesn't need to work so
hard first thing in the morning if the house is moderately warm when it is
told to heat the house.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
We had Bosch Greenstar I think 35i in the garage at the last house it had a frost stat connected due to risk of freezing. Ideally they should be set at 7C but you can go lower say 5/4C below that there is serious risk of freezing. The draw back using a frost stat is that it works independently of the the room stat so with a single heating circuit you will get radiators heating up at night if it kicks in. It should not have a major impact on gas usage. The extra cost of fuel has to be weighed against the potential damage caused by freezing.

As for comfort level differences it might be if you had an old mechanical room stat its settings may have been inaccurate, modern electronic versions tend to be much more accurate.

Richard

In article ,
Tricky Dicky writes
On Saturday, 2 January 2021 at 17:46:15 UTC, charles wrote:
In article ,
Cliff Topp wrote:
What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No. 7. The thermostat/programmer in the hallway was only rarely set to
above 18C. Only on the very coldest days of winter would we have to put
it up to about 20 or 21C.

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that
was set at the factory or if the installers set it.

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know it never had a frostat connected - unless it was factory-fitted
and integral to the boiler itself but definitely no external unit was
wired in.

The new installation *does* have a (Honeywell) frostat wired in and
it's keeping the heating on all night, irrespective of if I turn the
hallway stat/programmer down to a very low level or completely off.
This is really bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to *any* form of heating on at night and it's making it difficult to
sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?
Change the setting on the froststat so that it comes on at a lower
temperature.

I'm not sure if your pont 1 is true, The boiler doesn't need to work so
hard first thing in the morning if the house is moderately warm when it is
told to heat the house.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
We had Bosch Greenstar I think 35i in the garage at the last house it
had a frost stat connected due to risk of freezing. Ideally they should
be set at 7C but you can go lower say 5/4C below that there is serious
risk of freezing. The draw back using a frost stat is that it works
independently of the the room stat so with a single heating circuit you
will get radiators heating up at night if it kicks in. It should not
have a major impact on gas usage. The extra cost of fuel has to be
weighed against the potential damage caused by freezing.

As for comfort level differences it might be if you had an old
mechanical room stat its settings may have been inaccurate, modern
electronic versions tend to be much more accurate.

Richard
We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn on
boiler/pump as required independently of each other.

The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
--
bert

On Sat, 02 Jan 2021 16:44:26 +0000, Cliff Topp wrote:

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

Different thermostat, different mean temperatures, that isnt unusual.

On top of that, and perhaps even more importantly, is the frostat.

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is
really bad in three ways:

It sounds like it has been wired wrongly, and the frost stat is calling
for heat by opening the CH valve. It may be something to do with the
plumbing pipes too, there should be bypass piping to allow the boiler to
run without having the CH valve open.
You clearly know nothing about it, and it sounds like your fitter didnt
either, so probably time to get someone in who knows what they are doing.

On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port valve,
and don't normally need a by-pass.

The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump willÂ* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger

On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the boiler and controlled the CH valve just as the room stat hence the radiators getting lukewarm but unlike the room stat it was not wired through the programmer being solely triggered by the temperature falling into its set range.

Richard

On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit
on the flow temperature of the hot water produced by the boiler. With
old fixed output boilers that basically means it runs flat out until the
primary water exceeds that temp, and then cuts power to the burner
(while still running the pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the
flow temp to that limit by adjusting power to match the actual load. If
the load is too small that its unable to modulate lower, then they
revert to the style of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No. 7. The thermostat/programmer in the hallway was only rarely set to
above 18C. Only on the very coldest days of winter would we have to put
it up to about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling
the same regardless of how cold it is - it would just run the heating
more frequently to compensate for the higher rate of heat loss. However
as you have discovered, that does not always work of the boiler can't
heat the place fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the
flow temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that was
set at the factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on
cold days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement
in condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the
"part load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in
the boiler, and that the electrical supply to the boiler must be left on
for the thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is
really bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to *any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the
loft would cool faster than the boiler - but that seems unlikely since
the boilers one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too
high a temperature. Since the boiler has its own internal stat, I would
be tempted to simply disconnect the "call for heat" from the frost stat
and see how that works.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the boiler and controlled the CH valve just as the room stat hence the radiators getting lukewarm but unlike the room stat it was not wired through the programmer being solely triggered by the temperature falling into its set range.


A properly wired frost stat should be wired in series with a pipe stat.


--
Adam

On 03/01/2021 07:39, ARW wrote:
On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the boiler
and controlled the CH valve just as the room stat hence the radiators
getting lukewarm but unlike the room stat it was not wired through the
programmer being solely triggered by the temperature falling into its
set range.


A properly wired frost stat should be wired in series with a pipe stat.

Don't you mean in parallel? A pipe-stat is a very 'local' temperature
measurement and would turn off the boiler virtually as soon as it fired up?

On 02/01/2021 22:18, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn
on boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port valve,
and don't normally need a by-pass.

The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump willÂ* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!

If that is likely then maybe you need to think carefully at how
good (or bad) your house is insulated.

John Rumm wrote on 03/01/2021 :
On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit on
the flow temperature of the hot water produced by the boiler. With old fixed
output boilers that basically means it runs flat out until the primary water
exceeds that temp, and then cuts power to the burner (while still running the
pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the flow
temp to that limit by adjusting power to match the actual load. If the load
is too small that its unable to modulate lower, then they revert to the style
of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to No.
7. The thermostat/programmer in the hallway was only rarely set to above
18C. Only on the very coldest days of winter would we have to put it up to
about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling the
same regardless of how cold it is - it would just run the heating more
frequently to compensate for the higher rate of heat loss. However as you
have discovered, that does not always work of the boiler can't heat the place
fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the flow
temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees Celcius.
Both heating and HW are set to 56C but I don't know if that was set at the
factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on cold
days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement in
condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was more
than comfortable for us but the new stat/prog has to be set to at least 20C
or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the "part
load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I know
it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in the
boiler, and that the electrical supply to the boiler must be left on for the
thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is really
bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used to
*any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the loft
would cool faster than the boiler - but that seems unlikely since the boilers
one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too high a
temperature. Since the boiler has its own internal stat, I would be tempted
to simply disconnect the "call for heat" from the frost stat and see how that
works.

Thanks John, very helpful. I'll have a look at those links now.

On 03/01/2021 10:06, Fredxx wrote:
On 03/01/2021 07:39, ARW wrote:
On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the
boiler and controlled the CH valve just as the room stat hence the
radiators getting lukewarm but unlike the room stat it was not wired
through the programmer being solely triggered by the temperature
falling into its set range.


A properly wired frost stat should be wired in series with a pipe stat.

Don't you mean in parallel? A pipe-stat is a very 'local' temperature
measurement and would turn off the boiler virtually as soon as it fired up?



No. In series.

The pipe stat is supposed to be on the return pipe to the boiler at say
20 deg.



--
Adam

On 3 Jan 2021 at 12:27:11 GMT, "ARW" wrote:

On 03/01/2021 10:06, Fredxx wrote:
On 03/01/2021 07:39, ARW wrote:
On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the
boiler and controlled the CH valve just as the room stat hence the
radiators getting lukewarm but unlike the room stat it was not wired
through the programmer being solely triggered by the temperature
falling into its set range.


A properly wired frost stat should be wired in series with a pipe stat.

Don't you mean in parallel? A pipe-stat is a very 'local' temperature
measurement and would turn off the boiler virtually as soon as it fired up?



No. In series.

The pipe stat is supposed to be on the return pipe to the boiler at say
20 deg.

As a matter of interest, what is that supposed to achieve? And does it
exclude the possibility of pipes in the loft freezing while the boiler is
still cooling towards freezing?

--
Roger Hayter

On 03/01/2021 12:16, Andrew wrote:
On 02/01/2021 22:18, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn
on boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve, and don't normally need a by-pass.

The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump willÂ* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank
for HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!

If that is likely then maybe you need to think carefully at how
good (or bad) your house is insulated.

Unless the boiler is in an unheated outhouse or attic, why would that be
any more likely to freeze than the pipes?
--
Cheers,
Roger

On 3 Jan 2021 12:31:26 GMT, Roger Hayter wrote:

A properly wired frost stat should be wired in series with a
pipe
stat.

Don't you mean in parallel? A pipe-stat is a very 'local'
temperature
measurement and would turn off the boiler virtually as soon as it

fired up?

No. In series.

The pipe stat is supposed to be on the return pipe to the boiler
at say
20 deg.

As a matter of interest, what is that supposed to achieve?

Well you're only worried about the heat exchanger or pipe work
freezing. You're not overly worried about the loft/garage being
maintained at 7 C or WHY. Once the boiler has fired long enough to
raise the return to 20 C you don't need to run the boiler any longer.
I think I'd be happier with that return temp to be above the likely
maximum house temp though, so heat from the house doesn't turn off
the frost protection. Say 30 C.

Indeed one might get satisfactory frost protection by just running
the CH pump with the CH valve open. Would only work if the heating
was on, so the house was warm, and maintained warm, even if set back.

--
Cheers
Dave.

On Sun, 3 Jan 2021 12:56:56 +0000, Roger Mills wrote:

Unless the boiler is in an unheated outhouse or attic, why would that be
any more likely to freeze than the pipes?

Boiler has balanced flue that could allow cold external air to
circulate through the heat exchnager.

--
Cheers
Dave.

In article ,
Cliff Topp wrote:
Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius. Both heating and HW are set to 56C but I don't know if that
was set at the factory or if the installers set it.

We are finding that 18C on the old stat/programmer in the hallway was
more than comfortable for us but the new stat/prog has to be set to at
least 20C or 21C to 'feel' as warm as it was before.

56C is likely well below the temperature the old boiler ran at. Meaning
the rads might well struggle to heat the house. So just what a room stat
says may not be achievable.

--
*No I haven't stolen it , I'm just a **** driver*

Dave Plowman London SW
To e-mail, change noise into sound.

John Rumm formulated the question :
On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit on
the flow temperature of the hot water produced by the boiler. With old fixed
output boilers that basically means it runs flat out until the primary water
exceeds that temp, and then cuts power to the burner (while still running the
pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the flow
temp to that limit by adjusting power to match the actual load. If the load
is too small that its unable to modulate lower, then they revert to the style
of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to No.
7. The thermostat/programmer in the hallway was only rarely set to above
18C. Only on the very coldest days of winter would we have to put it up to
about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling the
same regardless of how cold it is - it would just run the heating more
frequently to compensate for the higher rate of heat loss. However as you
have discovered, that does not always work of the boiler can't heat the place
fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the flow
temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees Celcius.
Both heating and HW are set to 56C but I don't know if that was set at the
factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on cold
days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement in
condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was more
than comfortable for us but the new stat/prog has to be set to at least 20C
or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the "part
load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I know
it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in the
boiler, and that the electrical supply to the boiler must be left on for the
thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is really
bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used to
*any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the loft
would cool faster than the boiler - but that seems unlikely since the boilers
one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too high a
temperature. Since the boiler has its own internal stat, I would be tempted
to simply disconnect the "call for heat" from the frost stat and see how that
works.

Just FYI if anyone is interested you can see photos of the setup he
https://drive.google.com/drive/folde...Zm?usp=sharing

or if that wraps incorrectly https://tinyurl.com/yabpmsco

On Sunday, 3 January 2021 at 16:25:19 UTC, Cliff Topp wrote:
John Rumm formulated the question :
On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit on
the flow temperature of the hot water produced by the boiler. With old fixed
output boilers that basically means it runs flat out until the primary water
exceeds that temp, and then cuts power to the burner (while still running the
pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the flow
temp to that limit by adjusting power to match the actual load. If the load
is too small that its unable to modulate lower, then they revert to the style
of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to No.
7. The thermostat/programmer in the hallway was only rarely set to above
18C. Only on the very coldest days of winter would we have to put it up to
about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling the
same regardless of how cold it is - it would just run the heating more
frequently to compensate for the higher rate of heat loss. However as you
have discovered, that does not always work of the boiler can't heat the place
fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the flow
temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees Celcius.
Both heating and HW are set to 56C but I don't know if that was set at the
factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on cold
days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement in
condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was more
than comfortable for us but the new stat/prog has to be set to at least 20C
or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the "part
load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I know
it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in the
boiler, and that the electrical supply to the boiler must be left on for the
thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is really
bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used to
*any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the loft
would cool faster than the boiler - but that seems unlikely since the boilers
one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too high a
temperature. Since the boiler has its own internal stat, I would be tempted
to simply disconnect the "call for heat" from the frost stat and see how that
works.
Just FYI if anyone is interested you can see photos of the setup he
https://drive.google.com/drive/folde...Zm?usp=sharing

or if that wraps incorrectly https://tinyurl.com/yabpmsco
Thats the arrangement we had frost stat and pipe stat and as Adam mentioned wired in series. If you did not have the pipe stat the frost stat on its own would keep the boiler running as in a garage, outhouse or loft the boiler firing up would do little to raise the temperature. Having the pipe stat setting the upper temperature for the return flow shuts the boiler down preventing continuous operation.

Richard

On 03/01/2021 17:22, Tricky Dicky wrote:
On Sunday, 3 January 2021 at 16:25:19 UTC, Cliff Topp wrote:
John Rumm formulated the question :
On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit on
the flow temperature of the hot water produced by the boiler. With old fixed
output boilers that basically means it runs flat out until the primary water
exceeds that temp, and then cuts power to the burner (while still running the
pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the flow
temp to that limit by adjusting power to match the actual load. If the load
is too small that its unable to modulate lower, then they revert to the style
of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to No.
7. The thermostat/programmer in the hallway was only rarely set to above
18C. Only on the very coldest days of winter would we have to put it up to
about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling the
same regardless of how cold it is - it would just run the heating more
frequently to compensate for the higher rate of heat loss. However as you
have discovered, that does not always work of the boiler can't heat the place
fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the flow
temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees Celcius.
Both heating and HW are set to 56C but I don't know if that was set at the
factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on cold
days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement in
condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was more
than comfortable for us but the new stat/prog has to be set to at least 20C
or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the "part
load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I know
it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in the
boiler, and that the electrical supply to the boiler must be left on for the
thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is really
bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used to
*any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the loft
would cool faster than the boiler - but that seems unlikely since the boilers
one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too high a
temperature. Since the boiler has its own internal stat, I would be tempted
to simply disconnect the "call for heat" from the frost stat and see how that
works.
Just FYI if anyone is interested you can see photos of the setup he
https://drive.google.com/drive/folde...Zm?usp=sharing

or if that wraps incorrectly https://tinyurl.com/yabpmsco
Thats the arrangement we had frost stat and pipe stat and as Adam mentioned wired in series. If you did not have the pipe stat the frost stat on its own would keep the boiler running as in a garage, outhouse or loft the boiler firing up would do little to raise the temperature. Having the pipe stat setting the upper temperature for the return flow shuts the boiler down preventing continuous operation.

Richard



It seems that someone more mature than myself[1] actually did a video


https://www.youtube.com/watch?v=e4MX...annel=JohnWard

[1] I never want to grow up

--
Adam

It happens that ARW formulated :
On 03/01/2021 17:22, Tricky Dicky wrote:
On Sunday, 3 January 2021 at 16:25:19 UTC, Cliff Topp wrote:
John Rumm formulated the question :
On 02/01/2021 16:44, Cliff Topp wrote:

What is the relationship between the controls on the boiler itself, the
thermostat/programmer in the hallway and the heat in the rooms?

On a traditional setup, the stat on the boiler will set the upper limit
on
the flow temperature of the hot water produced by the boiler. With old
fixed
output boilers that basically means it runs flat out until the primary
water
exceeds that temp, and then cuts power to the burner (while still running
the
pump) until the temp falls.

With more modern modulating output boilers, they will aim to set the flow
temp to that limit by adjusting power to match the actual load. If the
load
is too small that its unable to modulate lower, then they revert to the
style
of operation used by fixed output boilers.

Our previous boiler was an Alpha CD32C and the boiler controls for both
heating and hot water were numbered from 0 to 9, and both were set to
No.
7. The thermostat/programmer in the hallway was only rarely set to above
18C. Only on the very coldest days of winter would we have to put it up
to
about 20 or 21C.

In a perfect world, the stat in the hall ought to keep the place feeling
the
same regardless of how cold it is - it would just run the heating more
frequently to compensate for the higher rate of heat loss. However as you
have discovered, that does not always work of the boiler can't heat the
place
fast enough on cold days.

(this is where weather compensation systems can be used to ramp up the
flow
temperature on the boiler in sympathy with the external temperature)

Our new boiler is a Worcester Greenstar 30i and instead of the boiler
controls being numbered 0 to 9, the readout is in actual degrees
Celcius.
Both heating and HW are set to 56C but I don't know if that was set at
the
factory or if the installers set it.

Probably set by the installers. Also probably a bit on the low side on
cold
days unless you have oversized radiators.

(54 degrees is the *return* temp at which you get a notable improvement
in
condensing efficiency for the boiler)

We are finding that 18C on the old stat/programmer in the hallway was
more
than comfortable for us but the new stat/prog has to be set to at least
20C
or 21C to 'feel' as warm as it was before.

I don't know what the *actual* temp of the rooms is as we don't have a
standalone thermometer, but it's weird trying to get used to this new
system.

You will probably need to set the temp for the rads on the boiler a bit
higher during the colder parts of the year. 56 will be fine for the "part
load" months.

On top of that, and perhaps even more importantly, is the frostat.

The old Alpha boiler was up in the loft for 14 years and as far as I
know
it never had a frostat connected - unless it was factory-fitted and
integral to the boiler itself but definitely no external unit was wired
in.


See 5.8 (7):

https://www.alpha-innovation.co.uk/c...%2010%2005.pdf

"7.Explain to the User that an internal frost thermostat is fitted in the
boiler, and that the electrical supply to the boiler must be left on for
the
thermostat to operate"

The new installation *does* have a (Honeywell) frostat wired in and it's
keeping the heating on all night, irrespective of if I turn the hallway
stat/programmer down to a very low level or completely off. This is
really
bad in three ways:

1. Extra gas used equals bigger bills
2. Even though the rads are only lukewarm to the touch, we aren't used
to
*any* form of heating on at night and it's making it difficult to sleep
3. The pipes and rads creak and groan a lot which is making it almost
impossible to sleep!

Any advice?

Well firstly a frost stat *should* override any others - its there as a
failsafe. However the greenstar also has an internal frost stat:

https://www.worcester-bosch.co.uk/su...20811923/12545

It might be that the installers were worried that the pipework in the
loft
would cool faster than the boiler - but that seems unlikely since the
boilers
one kicks in a 8 degrees.

ISTM that the external stat has been wired incorrectly or set at too high
a
temperature. Since the boiler has its own internal stat, I would be
tempted
to simply disconnect the "call for heat" from the frost stat and see how
that
works.
Just FYI if anyone is interested you can see photos of the setup he
https://drive.google.com/drive/folde...Zm?usp=sharing

or if that wraps incorrectly https://tinyurl.com/yabpmsco
Thats the arrangement we had frost stat and pipe stat and as Adam
mentioned wired in series. If you did not have the pipe stat the frost stat
on its own would keep the boiler running as in a garage, outhouse or loft
the boiler firing up would do little to raise the temperature. Having the
pipe stat setting the upper temperature for the return flow shuts the
boiler down preventing continuous operation.

Richard



It seems that someone more mature than myself[1] actually did a video


https://www.youtube.com/watch?v=e4MX...annel=JohnWard

[1] I never want to grow up

Brilliant, cheers :-)

On 03/01/2021 14:06, Dave Liquorice wrote:
On Sun, 3 Jan 2021 12:56:56 +0000, Roger Mills wrote:

Unless the boiler is in an unheated outhouse or attic, why would that be
any more likely to freeze than the pipes?

Boiler has balanced flue that could allow cold external air to
circulate through the heat exchnager.


Why would it do that without the fan running? "Balanced" means equal
input and output pressures.
--
Cheers,
Roger

On 03/01/2021 12:27, ARW wrote:
On 03/01/2021 10:06, Fredxx wrote:
On 03/01/2021 07:39, ARW wrote:
On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank
for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.
But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the
boiler and controlled the CH valve just as the room stat hence the
radiators getting lukewarm but unlike the room stat it was not wired
through the programmer being solely triggered by the temperature
falling into its set range.


A properly wired frost stat should be wired in series with a pipe stat.

Don't you mean in parallel? A pipe-stat is a very 'local' temperature
measurement and would turn off the boiler virtually as soon as it
fired up?



No. In series.

The pipe stat is supposed to be on the return pipe to the boiler at say
20 deg.

I see the idea, but not all pipes are heated, nor next to a CH pipe.
Therefore it's not something I would implement.

If you want to save the primary circuit from freezing then only a small
amount of antifreeze is required to make the water turn into a mush
rather than solid ice. If there's a concern over toxicity then propylene
glycol can be used.
https://www.healthline.com/nutrition/propylene-glycol

I have suffered a pipeburst myself and another member of the family had
a more serious burst pipe on an upper floor which did quite a bit of
damage to the floors below. I now always turn off the water if I leave
the house during a cold spell.

I'll think I'll stick to my programmable thermostat with its own built
in frost setting of 5C.

On 2021-01-03 7:52 p.m., Fredxx wrote:
On 03/01/2021 12:27, ARW wrote:
On 03/01/2021 10:06, Fredxx wrote:
On 03/01/2021 07:39, ARW wrote:
On 02/01/2021 23:17, Tricky Dicky wrote:
On Saturday, 2 January 2021 at 22:18:47 UTC, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on
boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves
for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve,
and don't normally need a by-pass.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on
tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck
again.
But if you *only* run the boiler and don't heat the rads, they and
the
pipework could freeze up. You wouldn't want that, surely?!
--
Cheers,
Roger
Agreed Roger our frost stat was a separate unit not part of the
boiler and controlled the CH valve just as the room stat hence the
radiators getting lukewarm but unlike the room stat it was not
wired through the programmer being solely triggered by the
temperature falling into its set range.


A properly wired frost stat should be wired in series with a pipe stat.

Don't you mean in parallel? A pipe-stat is a very 'local' temperature
measurement and would turn off the boiler virtually as soon as it
fired up?



No. In series.

The pipe stat is supposed to be on the return pipe to the boiler at
say 20 deg.

I see the idea, but not all pipes are heated, nor next to a CH pipe.
Therefore it's not something I would implement.

If you want to save the primary circuit from freezing then only a small
amount of antifreeze is required to make the water turn into a mush
rather than solid ice. If there's a concern over toxicity then propylene
glycol can be used.
Â* https://www.healthline.com/nutrition/propylene-glycol

I have suffered a pipeburst myself and another member of the family had
a more serious burst pipe on an upper floor which did quite a bit of
damage to the floors below. I now always turn off the water if I leave
the house during a cold spell.

I'll think I'll stick to my programmable thermostat with its own built
in frost setting of 5C.

you mean you didn't use heat tape when the house was being built

On 03/01/2021 23:22, Roger Mills wrote:
On 03/01/2021 14:06, Dave Liquorice wrote:
On Sun, 3 Jan 2021 12:56:56 +0000, Roger Mills wrote:

Unless the boiler is in an unheated outhouse or attic, why would that be
any more likely to freeze than the pipes?

Boiler has balanced flue that could allow cold external air to
circulate through the heat exchnager.


Why would it do that without the fan running? "Balanced" means equal
input and output pressures.

There are 'old fashioned' balanced flue boilers that are not
fan-forced. I suspect they are the most ineffient types going
and ?most have now been recycled into Nespressos. I regularly
see properties with a modern 4 inch balanced flue adjacent to
a bricked up hole that was about a foot square where the old
balanced flue came out.

On 04/01/2021 13:28, Andrew wrote:
On 03/01/2021 23:22, Roger Mills wrote:
On 03/01/2021 14:06, Dave Liquorice wrote:
On Sun, 3 Jan 2021 12:56:56 +0000, Roger Mills wrote:

Unless the boiler is in an unheated outhouse or attic, why would
that be
any more likely to freeze than the pipes?

Boiler has balanced flue that could allow cold external air to
circulate through the heat exchnager.


Why would it do that without the fan running? "Balanced" means equal
input and output pressures.

There are 'old fashioned' balanced flue boilers that are not
fan-forced. I suspect they are the most ineffient types going
and ?most have now been recycled into Nespressos. I regularly
see properties with a modern 4 inch balanced flue adjacent to
a bricked up hole that was about a foot square where the old
balanced flue came out.

don't worry we will soon be forced to remove akk our gas boilers ...

In article , Roger Mills
writes
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn
on boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve, and don't normally need a by-pass.

Thank you . Couldn't remember which was which off the top of my head.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank for
HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
No they would be opened up by the room stat set much above freezing
--
bert

In article , Roger Mills
writes
On 03/01/2021 12:16, Andrew wrote:
On 02/01/2021 22:18, Roger Mills wrote:
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which
turn on boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves
for each zone and a by-pass valve. Y-Plan systems use a single
3-port valve, and don't normally need a by-pass.

The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump will* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank
for HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and
the pipework could freeze up. You wouldn't want that, surely?!
If that is likely then maybe you need to think carefully at how
good (or bad) your house is insulated.

Unless the boiler is in an unheated outhouse or attic, why would that
be any more likely to freeze than the pipes?
In my case its in the corner of the integral garage. With a belt and
braces approach I also have a greenhouse heater in there with a frost
setting.
--
bert

On 04/01/2021 13:28, Andrew wrote:
On 03/01/2021 23:22, Roger Mills wrote:
On 03/01/2021 14:06, Dave Liquorice wrote:
On Sun, 3 Jan 2021 12:56:56 +0000, Roger Mills wrote:

Unless the boiler is in an unheated outhouse or attic, why would
that be
any more likely to freeze than the pipes?

Boiler has balanced flue that could allow cold external air to
circulate through the heat exchnager.


Why would it do that without the fan running? "Balanced" means equal
input and output pressures.

There are 'old fashioned' balanced flue boilers that are not
fan-forced. I suspect they are the most ineffient types going
and ?most have now been recycled into Nespressos. I regularly
see properties with a modern 4 inch balanced flue adjacent to
a bricked up hole that was about a foot square where the old
balanced flue came out.

Yes, indeed. But the non fan-assisted flues required some thermal
activity in the boiler in order to expel the products of combustion and
draw in fresh air. There would be negligible circulation without that.
--
Cheers,
Roger

On 04/01/2021 20:15, bert wrote:
In article , Roger Mills
writes
On 02/01/2021 19:33, bert wrote:

We have Y plan system (I think)
CH and HW are controlled independently by motorised valves which turn
onÂ* boiler/pump as required independently of each other.

More likely to be an S-Plan if there are separate motorised valves for
each zone and a by-pass valve. Y-Plan systems use a single 3-port
valve, and don't normally need a by-pass.

Thank you . Couldn't remember which was which off the top of my head.
The boiler (Worcester Bosch) has a built in frost stat, but if that
activates the pump willÂ* only run on the bypass overrun circuit. It
cannot open the motorised valves to put the heating on. They are
controlled by the thermostats, one in hall for CH and done on tank
for HW always assuming the specific timer is ON.
But our system is over 10 years old. Maybe progress has struck again.

But if you *only* run the boiler and don't heat the rads, they and the
pipework could freeze up. You wouldn't want that, surely?!
No they would be opened up by the room stat set much above freezing

Are you sure? If the heating's on all the time anyway, there's no point
in having a frost stat.

If the timer isn't calling for heat, the room stat won't do anything
regardless of the temperature, and you'll be dependent on the frost stat.
--
Cheers,
Roger

Andrew wrote:

There are 'old fashioned' balanced flue boilers that are not
fan-forced. I suspect they are the most ineffient types going
and ?most have now been recycled into Nespressos. I regularly
see properties with a modern 4 inch balanced flue adjacent to
a bricked up hole that was about a foot square where the old
balanced flue came out.

Mine's avoiding getting recycled, 78.something% SEDBUK rating last time
I looked, doesn't justify the spend to replace it