"Davey" wrote in message
...
On Fri, 22 Jan 2016 22:34:20 +0000
Roger Mills wrote:

On 21/01/2016 21:21, ARW wrote:
"Roger Mills" wrote in message
...

*But*, from what I can make out, you can't have space heating
without the possibility of heating the DHW up to boiler
temperature. The water coming out of the taps could thus be
dangerously hot unless you turn down the boiler stat to a level
which will probably not make the radiators hot enough in cold
weather. In addition, the boiler is cycling on its own stat and
wasting energy even when there's no demand.

That sounds just like a gravity fed system:-)


Well, it behaves in a similar way, despite being fully pumped - yes.

When I installed a gravity HW/pumped CH system in my previous house
way back in the 1960's I did at least put a Cyltrol valve in the HW
return - which stopped the DHW getting too hot. Davey's system
doesn't even have anything which does that.

I have thought a bit about this. In answer to Fredxx, it is not a let,
in fact, the lease expressly forbids this. But it is still a valid
thought, so:

My own experience working in industry tells me that holding metal in a
150 F. atmosphere (industrial car body paint ovens) is perfectly
acceptable, whereas 160 F. becomes unsustainable after more than a few
minutes. This would indicate that air at 150 F. is ok.
For water, I can find various tables that indicate that 150 F. water
should not be kept in contact with skin for more than about 1.5-2
seconds, risking burns if kept there longer. This sounds fair,
considering the difference in thermal properties between air and
water, and provides adequate time to snatch a hand away from a hot
stream of water from a tap.
So for safety, 140 F. would seem to be a target maximum hot water
temperature, which is what I have seen other tank thermostats set to.

For the system described, the now so-called 'B' system (!), the first
consideration is that the tank 'stat needs to be set higher than the
boiler 'stat, to keep the valve open and water circulating through the
radiators if needed. If it were the other way round, it could create the
perverse condition where the circulation was shut down due to high tank
temperature, but the lack of circulation would mean that there was no
way for the heat to be lost. So we will put the tank 'stat 10 F. higher
than the boiler 'stat.
If we then set the boiler 'stat at 130 F., the circulated water can
never exceed this temperature, as this is where its heat comes from.
The tank 'stat would be set at this plus 10, ie 140 F., ensuring
continued circulation (according to the programmer), and so even if the
boiler 'ran away' for some reason, the tank 'stat would shut down the
circulation and Domestic Hot Water supply at 140 F, a full 10 F. below
the 150 calculated earlier. This would still be the undesirable
no-circulation condition described earlier, but would at least shut
off the pump and boiler, as the boiler is powered through this 'stat.
If both radiator control and Hot Water proved fine, then both
thermostats could be set 10 F. lower, maybe even twice.

So the next time I go there, I will set the tank 'stat at 140 F., and
the boiler 'stat at 130 F. And although I have no way to check the
finite accuracy of them, I will operate them and compare them to each
other, to confirm an agreement or not of their settings, and testing
of the hot water to check that it is not scalding.


I believe you need a rethink of the setup.

Let's start with a clean sheet.

Which of these are true?

1. The pump circulates the water around both the HW and the CH circuits.
2. There is a valve on the CH side of the pumped water.
3. The CH ON of the programmer ONLY opens the valve on the CH circuit when
the room stat says call for heat
4. The HW ON of the programmer operates both the boiler and the pump when
the cylinder stat calls for heat

--
Adam

On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

My own experience working in industry tells me that holding metal
in a 150 F. atmosphere (industrial car body paint ovens) is
perfectly acceptable, whereas 160 F. becomes unsustainable after
more than a few minutes. This would indicate that air at 150 F. is
ok. For water, I can find various tables that indicate that 150 F.
water should not be kept in contact with skin for more than about
1.5-2 seconds, risking burns if kept there longer. This sounds fair,
considering the difference in thermal properties between air and
water, and provides adequate time to snatch a hand away from a hot
stream of water from a tap.
So for safety, 140 F. would seem to be a target maximum hot water
temperature, which is what I have seen other tank thermostats set
to.

For the system described, the now so-called 'B' system (!), the
first consideration is that the tank 'stat needs to be set higher
than the boiler 'stat, to keep the valve open and water circulating
through the radiators if needed. If it were the other way round, it
could create the perverse condition where the circulation was shut
down due to high tank temperature, but the lack of circulation
would mean that there was no way for the heat to be lost. So we
will put the tank 'stat 10 F. higher than the boiler 'stat.
If we then set the boiler 'stat at 130 F., the circulated water can
never exceed this temperature, as this is where its heat comes from.
The tank 'stat would be set at this plus 10, ie 140 F., ensuring
continued circulation (according to the programmer), and so even if
the boiler 'ran away' for some reason, the tank 'stat would shut
down the circulation and Domestic Hot Water supply at 140 F, a full
10 F. below the 150 calculated earlier. This would still be the
undesirable no-circulation condition described earlier, but would
at least shut off the pump and boiler, as the boiler is powered
through this 'stat. If both radiator control and Hot Water proved
fine, then both thermostats could be set 10 F. lower, maybe even
twice.

So the next time I go there, I will set the tank 'stat at 140 F.,
and the boiler 'stat at 130 F. And although I have no way to check
the finite accuracy of them, I will operate them and compare them
to each other, to confirm an agreement or not of their settings,
and testing of the hot water to check that it is not scalding.


I believe you need a rethink of the setup.

Why? If it works, why f..k with it?


Let's start with a clean sheet.


If you insist, but be alerted that I have no intention if doing anything
to the piping layout. There are five flats in the building, all
converted at the same time, by the same contractor, in 1976. Nothing is
known about there ever having been any scalding problems, and there
are regular leaseholder meetings at which this would have been
brought up. Even when the flat in question had a defective room
'stat, it was still perfectly habitable, just not properly responsive.
Since the room 'stat was totally useless, and I have now fixed it,
this is no longer an issue. I intend to set the thermostats as
described above.

Which of these are true?

1. The pump circulates the water around both the HW and the CH
circuits.
2. There is a valve on the CH side of the pumped water.
3. The CH ON of the programmer ONLY opens the valve on the CH circuit
when the room stat says call for heat.
4. The HW ON of the programmer operates both the boiler and the pump
when the cylinder stat calls for heat.

All of them.
--
Davey.

On Saturday, 23 January 2016 16:56:57 UTC, Davey wrote:
On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

I believe you need a rethink of the setup.

Why? If it works, why f..k with it?

mystery to me too. Folk here often recommend rejigging things to the latest formats when there's no evident need.


NT

On 23/01/2016 19:26, wrote:
On Saturday, 23 January 2016 16:56:57 UTC, Davey wrote:
On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

I believe you need a rethink of the setup.

Why? If it works, why f..k with it?

mystery to me too. Folk here often recommend rejigging things to the latest formats when there's no evident need.

The addition of a single zone valve could mean the HW temperature could
be limited whilst the CH was running.

That is hardly the latest format and would cost all of one motorised valve.

I suppose we can't all be Luddites.

On Saturday, 23 January 2016 20:12:48 UTC, Fredxxx wrote:
On 23/01/2016 19:26, tabbypurr wrote:
On Saturday, 23 January 2016 16:56:57 UTC, Davey wrote:
On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

I believe you need a rethink of the setup.

Why? If it works, why f..k with it?

mystery to me too. Folk here often recommend rejigging things to the latest formats when there's no evident need.

The addition of a single zone valve could mean the HW temperature could
be limited whilst the CH was running.

The OP has explained that it already is. Not by thermostat & valve, but by the relative heat throughputs & on times. Old school, but it works.

That is hardly the latest format and would cost all of one motorised valve.

I suppose we can't all be Luddites.

to solve a nonexistent problem


NT

"Davey" wrote in message
...
On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

My own experience working in industry tells me that holding metal
in a 150 F. atmosphere (industrial car body paint ovens) is
perfectly acceptable, whereas 160 F. becomes unsustainable after
more than a few minutes. This would indicate that air at 150 F. is
ok. For water, I can find various tables that indicate that 150 F.
water should not be kept in contact with skin for more than about
1.5-2 seconds, risking burns if kept there longer. This sounds fair,
considering the difference in thermal properties between air and
water, and provides adequate time to snatch a hand away from a hot
stream of water from a tap.
So for safety, 140 F. would seem to be a target maximum hot water
temperature, which is what I have seen other tank thermostats set
to.

For the system described, the now so-called 'B' system (!), the
first consideration is that the tank 'stat needs to be set higher
than the boiler 'stat, to keep the valve open and water circulating
through the radiators if needed. If it were the other way round, it
could create the perverse condition where the circulation was shut
down due to high tank temperature, but the lack of circulation
would mean that there was no way for the heat to be lost. So we
will put the tank 'stat 10 F. higher than the boiler 'stat.
If we then set the boiler 'stat at 130 F., the circulated water can
never exceed this temperature, as this is where its heat comes from.
The tank 'stat would be set at this plus 10, ie 140 F., ensuring
continued circulation (according to the programmer), and so even if
the boiler 'ran away' for some reason, the tank 'stat would shut
down the circulation and Domestic Hot Water supply at 140 F, a full
10 F. below the 150 calculated earlier. This would still be the
undesirable no-circulation condition described earlier, but would
at least shut off the pump and boiler, as the boiler is powered
through this 'stat. If both radiator control and Hot Water proved
fine, then both thermostats could be set 10 F. lower, maybe even
twice.

So the next time I go there, I will set the tank 'stat at 140 F.,
and the boiler 'stat at 130 F. And although I have no way to check
the finite accuracy of them, I will operate them and compare them
to each other, to confirm an agreement or not of their settings,
and testing of the hot water to check that it is not scalding.


I believe you need a rethink of the setup.

Why? If it works, why f..k with it?


Let's start with a clean sheet.


If you insist, but be alerted that I have no intention if doing anything
to the piping layout. There are five flats in the building, all
converted at the same time, by the same contractor, in 1976. Nothing is
known about there ever having been any scalding problems, and there
are regular leaseholder meetings at which this would have been
brought up. Even when the flat in question had a defective room
'stat, it was still perfectly habitable, just not properly responsive.
Since the room 'stat was totally useless, and I have now fixed it,
this is no longer an issue. I intend to set the thermostats as
described above.

Which of these are true?

1. The pump circulates the water around both the HW and the CH
circuits.
2. There is a valve on the CH side of the pumped water.
3. The CH ON of the programmer ONLY opens the valve on the CH circuit
when the room stat says call for heat.
4. The HW ON of the programmer operates both the boiler and the pump
when the cylinder stat calls for heat.

All of them.


Scalding was not my concern. There is always a kettle for the thickos to
scald themselves if they want to.

I was thinking more along the lines of "let the DWH get as hot as the boiler
stat and still allow the CH to work regardless of the HW stat". As it is not
a nursing home or a home for special needs then the maximum HW temperature
does not concern me.

--
Adam

On 23/01/2016 13:16, Davey wrote:
On Fri, 22 Jan 2016 22:34:20 +0000
Roger wrote:

On 21/01/2016 21:21, ARW wrote:
"Roger wrote in message
...

*But*, from what I can make out, you can't have space heating
without the possibility of heating the DHW up to boiler
temperature. The water coming out of the taps could thus be
dangerously hot unless you turn down the boiler stat to a level
which will probably not make the radiators hot enough in cold
weather. In addition, the boiler is cycling on its own stat and
wasting energy even when there's no demand.

That sounds just like a gravity fed system:-)


Well, it behaves in a similar way, despite being fully pumped - yes.

When I installed a gravity HW/pumped CH system in my previous house
way back in the 1960's I did at least put a Cyltrol valve in the HW
return - which stopped the DHW getting too hot. Davey's system
doesn't even have anything which does that.

I have thought a bit about this. In answer to Fredxx, it is not a let,
in fact, the lease expressly forbids this. But it is still a valid
thought, so:

My own experience working in industry tells me that holding metal in a
150 F. atmosphere (industrial car body paint ovens) is perfectly
acceptable, whereas 160 F. becomes unsustainable after more than a few
minutes. This would indicate that air at 150 F. is ok.
For water, I can find various tables that indicate that 150 F. water
should not be kept in contact with skin for more than about 1.5-2
seconds, risking burns if kept there longer. This sounds fair,
considering the difference in thermal properties between air and
water, and provides adequate time to snatch a hand away from a hot
stream of water from a tap.
So for safety, 140 F. would seem to be a target maximum hot water
temperature, which is what I have seen other tank thermostats set to.

For the system described, the now so-called 'B' system (!), the first
consideration is that the tank 'stat needs to be set higher than the
boiler 'stat, to keep the valve open and water circulating through the
radiators if needed. If it were the other way round, it could create the
perverse condition where the circulation was shut down due to high tank
temperature, but the lack of circulation would mean that there was no
way for the heat to be lost. So we will put the tank 'stat 10 F. higher
than the boiler 'stat.
If we then set the boiler 'stat at 130 F., the circulated water can
never exceed this temperature, as this is where its heat comes from.
The tank 'stat would be set at this plus 10, ie 140 F., ensuring
continued circulation (according to the programmer), and so even if the
boiler 'ran away' for some reason, the tank 'stat would shut down the
circulation and Domestic Hot Water supply at 140 F, a full 10 F. below
the 150 calculated earlier. This would still be the undesirable
no-circulation condition described earlier, but would at least shut
off the pump and boiler, as the boiler is powered through this 'stat.
If both radiator control and Hot Water proved fine, then both
thermostats could be set 10 F. lower, maybe even twice.

So the next time I go there, I will set the tank 'stat at 140 F., and
the boiler 'stat at 130 F. And although I have no way to check the
finite accuracy of them, I will operate them and compare them to each
other, to confirm an agreement or not of their settings, and testing
of the hot water to check that it is not scalding.



If you set the boiler stat at 130F (~54C) there's no danger of scalding
hot water coming out of the taps.

But - unless the radiators have been grossly oversized - there *is* a
danger that you'll shiver in cold weather. The flow temperature round
the radiators probably needs to be around 80C (176F) to maintain a
decent room temperature.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On Sat, 23 Jan 2016 12:52:03 -0800 (PST)
wrote:

to solve a nonexistent problem


And that sums it up perfectly, to me. I appreciate all the input, but I
have no intention of changing anything.

--
Davey.

"Davey" wrote in message
...
On Sat, 23 Jan 2016 15:06:28 -0000
"ARW" wrote:

My own experience working in industry tells me that holding metal
in a 150 F. atmosphere (industrial car body paint ovens) is
perfectly acceptable, whereas 160 F. becomes unsustainable after
more than a few minutes. This would indicate that air at 150 F. is
ok. For water, I can find various tables that indicate that 150 F.
water should not be kept in contact with skin for more than about
1.5-2 seconds, risking burns if kept there longer. This sounds fair,
considering the difference in thermal properties between air and
water, and provides adequate time to snatch a hand away from a hot
stream of water from a tap.
So for safety, 140 F. would seem to be a target maximum hot water
temperature, which is what I have seen other tank thermostats set
to.

For the system described, the now so-called 'B' system (!), the
first consideration is that the tank 'stat needs to be set higher
than the boiler 'stat, to keep the valve open and water circulating
through the radiators if needed. If it were the other way round, it
could create the perverse condition where the circulation was shut
down due to high tank temperature, but the lack of circulation
would mean that there was no way for the heat to be lost. So we
will put the tank 'stat 10 F. higher than the boiler 'stat.
If we then set the boiler 'stat at 130 F., the circulated water can
never exceed this temperature, as this is where its heat comes from.
The tank 'stat would be set at this plus 10, ie 140 F., ensuring
continued circulation (according to the programmer), and so even if
the boiler 'ran away' for some reason, the tank 'stat would shut
down the circulation and Domestic Hot Water supply at 140 F, a full
10 F. below the 150 calculated earlier. This would still be the
undesirable no-circulation condition described earlier, but would
at least shut off the pump and boiler, as the boiler is powered
through this 'stat. If both radiator control and Hot Water proved
fine, then both thermostats could be set 10 F. lower, maybe even
twice.

So the next time I go there, I will set the tank 'stat at 140 F.,
and the boiler 'stat at 130 F. And although I have no way to check
the finite accuracy of them, I will operate them and compare them
to each other, to confirm an agreement or not of their settings,
and testing of the hot water to check that it is not scalding.

Let's start with a clean sheet.


If you insist, but be alerted that I have no intention if doing anything
to the piping layout.


My suggestion is

1. Set the tank stat to the temperature you would normally use if this was a
s or y plan
2. Set the boiler stat to the maximim temperature that is safe if there was
no tank stat
3. Use the switch on the valve to give a live to the pump and boiler when
the valve is operated.

This will allow the tank stat to control the HW temperature in the summer
and stop the possibility of a lock out on the CH in the winter.

--
Adam

On Sun, 24 Jan 2016 08:54:21 -0000
"ARW" wrote:

"Davey" wrote in message
...

snip

If you insist, but be alerted that I have no intention if doing
anything to the piping layout.


My suggestion is

1. Set the tank stat to the temperature you would normally use if
this was a s or y plan
2. Set the boiler stat to the maximim temperature that is safe if
there was no tank stat
3. Use the switch on the valve to give a live to the pump and boiler
when the valve is operated.

This will allow the tank stat to control the HW temperature in the
summer and stop the possibility of a lock out on the CH in the winter.


I have never used an 'S' or 'Y' plan system, so I will guess that the
Tank 'stat. setpoint would be say about 130 F., and the Boiler 'stat
about 140 F. ? That way, the boiler could always satisfy the tank heat
requirement.

Ok. The pump needs to run whenever heat is required by the programmer
and not prevented by the tank 'stat, due to the upside-down arrangement
of the boiler and tank, so those connections need to remain.

To incorporate your mod. 3, and maintain the tank 'stat as a safety
restriction on the over-generation of boiler heat, the output from
the valve switch would need to be inserted between the programmer and
the tank 'stat, or the output of the tank 'stat. But that would allow
the boiler to run ONLY when the room 'stat is calling for heat, which
is no good for DHW only.

So we leave the tank 'stat out of the HTG circuit, and let it just
control the DHW temp. When the Room 'stat asks for heat, the valve
opens, and power is fed to the switch from the Programmer HTG output,
the same one that feeds the Room 'stat, or the Room 'stat's output
feeding the valve motor, and when the valve proves open, sends power to
the pump and boiler. This now controls the boiler temp. according to
its own thermostat, and the Tank 'stat is taken out of the loop
entirely, as in your condition 2, above. That should work, bearing in
mind that the tank is now subject to whatever temp. the boiler is
sending out, instead of its own thermostat.

[I use 'HTG' in preference to 'CH' because that is what the Programmer,
and all my sketches, use].

I think it is unnecessary, but it is do-able without any pipework
modifications, and all electrical components are already there.
In fact, this modification requires only the moving of the wire
currently going to a blank terminal on the Programmer to a terminal two
spots away. Without digging into somebody else's airing cupboard, which
would be a gross intrusion of privacy, I cannot know what the original
intention and wiring were, and this might be the original design. Or
not.

This I can do whenever I am next there, I see no reason not to. Thanks.

--
Davey.

"Davey" wrote in message
...
On Sun, 24 Jan 2016 08:54:21 -0000
"ARW" wrote:

"Davey" wrote in message
...

snip

If you insist, but be alerted that I have no intention if doing
anything to the piping layout.


My suggestion is

1. Set the tank stat to the temperature you would normally use if
this was a s or y plan
2. Set the boiler stat to the maximim temperature that is safe if
there was no tank stat
3. Use the switch on the valve to give a live to the pump and boiler
when the valve is operated.

This will allow the tank stat to control the HW temperature in the
summer and stop the possibility of a lock out on the CH in the winter.


I have never used an 'S' or 'Y' plan system, so I will guess that the
Tank 'stat. setpoint would be say about 130 F., and the Boiler 'stat
about 140 F. ? That way, the boiler could always satisfy the tank heat
requirement.

Ok. The pump needs to run whenever heat is required by the programmer
and not prevented by the tank 'stat, due to the upside-down arrangement
of the boiler and tank, so those connections need to remain.

To incorporate your mod. 3, and maintain the tank 'stat as a safety
restriction on the over-generation of boiler heat, the output from
the valve switch would need to be inserted between the programmer and
the tank 'stat, or the output of the tank 'stat. But that would allow
the boiler to run ONLY when the room 'stat is calling for heat, which
is no good for DHW only.

So we leave the tank 'stat out of the HTG circuit, and let it just
control the DHW temp. When the Room 'stat asks for heat, the valve
opens, and power is fed to the switch from the Programmer HTG output,
the same one that feeds the Room 'stat, or the Room 'stat's output
feeding the valve motor, and when the valve proves open, sends power to
the pump and boiler. This now controls the boiler temp. according to
its own thermostat, and the Tank 'stat is taken out of the loop
entirely, as in your condition 2, above. That should work, bearing in
mind that the tank is now subject to whatever temp. the boiler is
sending out, instead of its own thermostat.

That is correct. And had this been a gravity HW system that is what you
would have had as there would be no tank stat.

[I use 'HTG' in preference to 'CH' because that is what the Programmer,
and all my sketches, use].

I think it is unnecessary, but it is do-able without any pipework
modifications, and all electrical components are already there.
In fact, this modification requires only the moving of the wire
currently going to a blank terminal on the Programmer to a terminal two
spots away. Without digging into somebody else's airing cupboard, which
would be a gross intrusion of privacy, I cannot know what the original
intention and wiring were, and this might be the original design. Or
not.

This I can do whenever I am next there, I see no reason not to. Thanks.


I am not so sure that there is a need to rely on the tank stat if boiler
stat fails closed. It may be worth seeing if you can get a manual for the
boiler and see if it has an overheat stat built into it. I am sure my old
Ideal Mexico boiler had one. Using the boiler stat to control the HW
temperature in winter is something only you can decide on. If you decide
that you need the tank stat as a safety feature then my mod is not doable
(although you could always stick a pipe stat on the boiler flow pipe that
would switch off the boiler and leave the pump running).

But let's keep it simple and cost free.

Sure the system is not going to be perfect but if it only takes a few
minutes and costs nothing to do or undo a few tweaks then why not try it? My
tweak would in winter just allow the rads to operate when the cylinder stat
is satisfied and the room stat is calling and in summer allow the HW to be
properly controlled by the cylinder stat.

BTW I found this a most interesting thread. Thanks for sharing it and for
managing to work out your plumbing and wiring of a "B" plan. Everyone has
learnt something.


--
Adam

On Sun, 24 Jan 2016 13:57:22 -0000
"ARW" wrote:

Sure the system is not going to be perfect but if it only takes a few
minutes and costs nothing to do or undo a few tweaks then why not try
it? My tweak would in winter just allow the rads to operate when the
cylinder stat is satisfied and the room stat is calling and in summer
allow the HW to be properly controlled by the cylinder stat.


As I mentioned, I will do this last modification when I am next there,
whenever that may be. Probably within a month, maybe less. I'll also
look for a boiler manual, I have the model number somewhere. I think,
from memory, it is an Ideal Standard, so should be easy to find.

BTW I found this a most interesting thread. Thanks for sharing it and
for managing to work out your plumbing and wiring of a "B" plan.
Everyone has learnt something.


It originally started as an appeal for help, but 'went all the way'.

--
Davey.

On 24/01/2016 12:31, Davey wrote:
I have never used an 'S' or 'Y' plan system, so I will guess that the
Tank 'stat. setpoint would be say about 130 F., and the Boiler 'stat
about 140 F. ? That way, the boiler could always satisfy the tank heat
requirement.

I haven't seen water temperatures in F for YEARS - I had to run a
conversion.

AIUI you need to take the tank up to 60C (140F) at intervals to keep
Legionnaire's disease at bay.

Andy

On Sun, 24 Jan 2016 21:20:15 +0000
Vir Campestris wrote:

On 24/01/2016 12:31, Davey wrote:
I have never used an 'S' or 'Y' plan system, so I will guess that
the Tank 'stat. setpoint would be say about 130 F., and the Boiler
'stat about 140 F. ? That way, the boiler could always satisfy the
tank heat requirement.

I haven't seen water temperatures in F for YEARS - I had to run a
conversion.


Well, this system was installed in 1976, and as far as I know, all
components, with the exception of the room thermostat (replaced by me
last week), and the Zone Valve (replaced by an unknown 'Professional
Installer' some months ago), are all original. Even the Room 'stat that
I replaced was in deg. F., it was just past its 'Best Before' date.

An old-school engineer I worked with in the years around 1972-1977
called the abandoning of Imperial units 'Metrifuction'. He had a
point......

--
Davey.

On Fri, 15 Jan 2016 00:27:52 +0000
Davey wrote:

I went to look at a flat's heating system yesterday, which I had been
told was not working properly. It was already known that the wiring
was f.....d up. None of this was due to me, but it is up to me to fix
it.

It looks like a standard 'C' Plan, but the Zone valve isn't sending
back an 'Open' signal, and I don't know if it even rotates. It
responds to the Manual actuator, but no switch changes state. The
valve would appear to be held open when the boiler is running, as the
system heats up. In fact the problem is controlling it, as
another part of the mess is that the Room Thermostat has been
bypassed and lots of wires joined together to make it all run, all or nothing.
This I can improve.

A different, but linked, puzzle. I was investigating the wiring of my
house heating system yesterday, it is a proper 'C' System, thankfully.
I was reminded that the wires from the cylinder 'stat, to terminal 8,
and back from there to the valve motor, are not there, they are joined
in the remote terminal box, and neither of them go downstairs to the
main System J-Box. Functionally, it's not a problem, but for
troubleshooting, it sucks.
I noticed during a period of Hot Water use, with the Heating turned off,
that terminal 10 remains powered, indicating either that the valve is
stuck Open (possible, it was once before), or that the tank 'stat is
remaining closed. It was the boiler 'stat that was controlling the
boiler operation.

Before I open up the access to the tank 'stat, (a fairly large
upheaval of the bathroom), what are optimal operating setpoints, or at
least their relationship, for a 'C' System? I seem to remember that the
cylinder 'stat is already set low. I know that one test for the valve
is to shut off both Heating and Hot Water and see if the boiler will
still run, and that shows if the valve is stuck in the Open
position, that is how the original failure was detected.

Any help welcome. The system works, but like the one in the flat, the
'B' System, it can be made to operate better.

--
Davey.

On 09/02/2016 12:00, Davey wrote:
On Fri, 15 Jan 2016 00:27:52 +0000
wrote:

I went to look at a flat's heating system yesterday, which I had been
told was not working properly. It was already known that the wiring
was f.....d up. None of this was due to me, but it is up to me to fix
it.

It looks like a standard 'C' Plan, but the Zone valve isn't sending
back an 'Open' signal, and I don't know if it even rotates. It
responds to the Manual actuator, but no switch changes state. The
valve would appear to be held open when the boiler is running, as the
system heats up. In fact the problem is controlling it, as
another part of the mess is that the Room Thermostat has been
bypassed and lots of wires joined together to make it all run, all or nothing.
This I can improve.

A different, but linked, puzzle. I was investigating the wiring of my
house heating system yesterday, it is a proper 'C' System, thankfully.
I was reminded that the wires from the cylinder 'stat, to terminal 8,
and back from there to the valve motor, are not there, they are joined
in the remote terminal box, and neither of them go downstairs to the
main System J-Box. Functionally, it's not a problem, but for
troubleshooting, it sucks.
I noticed during a period of Hot Water use, with the Heating turned off,
that terminal 10 remains powered, indicating either that the valve is
stuck Open (possible, it was once before), or that the tank 'stat is
remaining closed. It was the boiler 'stat that was controlling the
boiler operation.

Before I open up the access to the tank 'stat, (a fairly large
upheaval of the bathroom), what are optimal operating setpoints, or at
least their relationship, for a 'C' System? I seem to remember that the
cylinder 'stat is already set low. I know that one test for the valve
is to shut off both Heating and Hot Water and see if the boiler will
still run, and that shows if the valve is stuck in the Open
position, that is how the original failure was detected.

Any help welcome. The system works, but like the one in the flat, the
'B' System, it can be made to operate better.


When you say that the heating was turned off, was the HW also turned
off? If not, it's behaving like it's supposed to. If you're using hot
water, and reducing the tank temperature below the stat setting, then -
providing there's a HW demand from the programmer - you'd expect the
boiler to run to heat the tank up again.If there's *no* Hw demand, the
tank stat will have no effect even if stuck closed. If the boiler runs
under those circumstances - without the pump also running - it must be
being fed from the valve's NO contact, implying either that the valve is
stuck open (if the tank actually gets hot) or just that the valve's
switch is stuck in the position it would only normally be in when the
valve is open, even though the valve is closed. Under these
circumstances, the boiler would cycle on its own stat without actually
heating the tank.

With regards to stat settings - when everything is working properly - I
would set the tank stat to 55-60 (depending on how hot you like your hot
water) and the boiler stat to about 80 - assuming it's not a condensing
boiler. [Unlikely with a C-Plan system]. That will give the CH a decent
flow temperature, and also give the thermo-syphon HW system enough urge
to prevent it taking all day to heat the water.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On Tue, 09 Feb 2016 14:54:14 +0000
Roger Mills wrote:

When you say that the heating was turned off, was the HW also turned
off?

No, the HW was still on.
If not, it's behaving like it's supposed to. If you're using hot
water, and reducing the tank temperature below the stat setting, then
- providing there's a HW demand from the programmer - you'd expect
the boiler to run to heat the tank up again.If there's *no* Hw
demand, the tank stat will have no effect even if stuck closed. If
the boiler runs under those circumstances - without the pump also
running - it must be being fed from the valve's NO contact, implying
either that the valve is stuck open (if the tank actually gets hot)
or just that the valve's switch is stuck in the position it would
only normally be in when the valve is open, even though the valve is
closed. Under these circumstances, the boiler would cycle on its own
stat without actually heating the tank.

SWMBO stated that there was plenty of hot water for an extended shower,
and I have never found it lacking, so the tank is being heated ok.
If anything, the hot water is too hot, but not scalding. When I had a
problem before, the valve was stuck in the open position, but it freed
up ok. It might have done the same thing now.
The only way we knew there was a problem at all was when the boiler
service guy turned off the programmer outputs, but the boiler still ran
according to its own thermostat, which it should not have done.

With regards to stat settings - when everything is working properly -
I would set the tank stat to 55-60 (depending on how hot you like
your hot water) and the boiler stat to about 80 - assuming it's not a
condensing boiler.

Correct, it's an older boiler, and the service guy recommends that I
stick with it as long as it runs. I just had it 'de-kettled', the
system flushed, and new inhibitor added.

That will give
the CH a decent flow temperature, and also give the thermo-syphon HW
system enough urge to prevent it taking all day to heat the water.

Thanks, that makes sense, and sounds similar to what I think is there
now.

--
Davey.

On 09/02/2016 16:27, Davey wrote:


SWMBO stated that there was plenty of hot water for an extended shower,
and I have never found it lacking, so the tank is being heated ok.

The fact that plenty of hot water was coming out of the top of the tank
doesn't necessarily mean that the tank stat is above its set point and
therefore not calling for heat.

As hot water is drawn off from the top, it's replaced by cold water at
the bottom. There will be a vertical temperature gradient within the
tank. Depending on at what height the stat is fitted, it may well trip
and turn the boiler on even though the water at the top is still piping hot.

My belief is that your system is doing exactly what it says on the tin!
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.

On Tue, 09 Feb 2016 17:43:27 +0000
Roger Mills wrote:

On 09/02/2016 16:27, Davey wrote:


SWMBO stated that there was plenty of hot water for an extended
shower, and I have never found it lacking, so the tank is being
heated ok.

The fact that plenty of hot water was coming out of the top of the
tank doesn't necessarily mean that the tank stat is above its set
point and therefore not calling for heat.

As hot water is drawn off from the top, it's replaced by cold water
at the bottom. There will be a vertical temperature gradient within
the tank. Depending on at what height the stat is fitted, it may well
trip and turn the boiler on even though the water at the top is still
piping hot.

My belief is that your system is doing exactly what it says on the
tin!

Well that's good news! When I get the opportunity, I'll get access to
the tank, and operate the 'stat, while checking the operation. Access
to the valve is very difficult (of course, it seems to be normal), but
the J-Box is a bit easier.
This is not, however, a priority, as the system indeed produces hot
water and heating.

--
Davey.

Davey posted
Correct, it's an older boiler, and the service guy recommends that I
stick with it as long as it runs. I just had it 'de-kettled',

How did you do that? Limescale remover?


the system flushed, and new inhibitor added.

--
Les

On Wed, 17 Feb 2016 16:43:23 +0000
Big Les Wade wrote:

Davey posted
Correct, it's an older boiler, and the service guy recommends that I
stick with it as long as it runs. I just had it 'de-kettled',

How did you do that? Limescale remover?



A local well-regarded plumber came round with a pressurising pump and
container, and circulated some cleaning solution. He also removed and
cleaned the expansion tank, replaced the grotty fill valve, and put
inhibitor into the system.
Now it's nice and quiet.

--
Davey.