My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.

In article ,
stuart noble wrote:
My neighbour has just had a new Baxi combi installed. They've put TRVs
on all the rads bar one and have ripped out the old room thermostat. Is
this normal?

Normal for a poorly designed installation, yes. And remember that heating
system electrics are beyond most plumbers.

I find being able to set that to 15 or so useful if you're
leaving the house unoccupied for a few days but maybe that's not how
it's done these days.

Most sensible installers would recommend a programmable thermostat which
allows different temperatures to be set automatically throughout the day
and days of the week. You can set them for different temperatures for
night, morning, when you're out at work, and evening. And have designated
'weekend' days where you're likely to be in and want the same temperature
all day.

The rad without the TRV (in the bathroom) you
could fry an egg on. Just as well there aren't any kids about. It looks
as though you can adjust the CH temperature on the boiler but it's
already below 50% on the scale.

So if the weather gets very cold you alter the thermostat on the boiler?
Very convenient, that. For the installer's profits, certainly.

--
*Red meat is not bad for you. Fuzzy green meat is bad for you.

Dave Plowman London SW 12
RIP Acorn

stuart noble wrote:

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done these
days.


You switfh the whole heating off really. Or turn the TRV's down to frost
settings.


The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.



ou need one rad that doesn;t shut down, or some other form of bypass - a
radioator that will take the full flow when all teh others are shut down.

Bathroom is good since its a small room and needs the heat to keep
condesation down. Another option I favoured in the past was a small rad
in an airing cupboard. You can also fit a bypass loop that allopws teh
pump to circulate hot water without doing very much heating at all.

They've put TRVs on all the rads bar one and have ripped out the
old room thermostat. Is this normal?

There must be some sort of boiler interlock installed. Otherwise, the system
does not comply with the building regulations. The interlock is normally of
the form of a room thermostat. However, it is permissible to use TRVs and a
flow switch to detect that all the TRVs have closed off. You need to find
out if your system has such a switch. If it does not, get the installer back
and ask how the boiler interlock requirement of Part L1 is met.

Actually, thinking about it, it can't be compliant, as the bathroom radiator
without the TRV would mean that any such flow switch would be ineffective.

Christian.

"stuart noble" wrote in message
...
My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.

Lunacy. Who wants to go round the house 2 or 3 times a day turning rad
stats up and down? I'd get the fitter to put in a programmable room stat
and save all the hassle (and a load of money on unnecessary heating).

Rgds

Andy R

Actually, thinking about it, it can't be compliant, as the bathroom
radiator without the TRV would mean that any such flow switch would
be ineffective.

But then, I suppose you could put the switch after the bathroom rad. I would
imagine such a system would be compliant.

BOILER ----+-----FS----+----+
| | | |
| RAD TRAD TRAD
| | | |
+----------+-----------+----+

RAD = bathroom radiator/bypass
FS = flow switch interlock
TRAD = TRVed radiator
= pump, runs continuously, or pulses occasionally when FS off

The bathroom radiator would only be on if another radiator in the system
required heat.

Christian.

"stuart noble" wrote in message
...
My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.



If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.

On Fri, 12 Dec 2003 12:34:59 +0000, stuart noble wrote:

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.

Ours had been installed like that. I bought a Danfoss TP5
http://www.screwfix.com/app/sfd/cat/...39276&ts=43568
which is terrific. It beats going round 17 rads when I want to just tweak
the temperature a bit. I like being able to set an 'overnight' temperature
- somewhere between a froststat protection setting and the usual evening
setting. So if it gets really cold overnight, the heating will come on,
just enough to take the bite out the air.

Dougie

Andy R wrote:

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done

these

days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.


Lunacy. Who wants to go round the house 2 or 3 times a day turning rad
stats up and down?


The question was what to do if you went aay for a few days actually. Its
not possible to go a way for a few days 2 or 3 times a day...

"Dave Plowman" wrote in message
...
In article ,
stuart noble wrote:
My neighbour has just had a new Baxi combi installed. They've put TRVs
on all the rads bar one and have ripped out the old room thermostat. Is
this normal?

Normal for a poorly designed installation, yes. And remember that heating
system electrics are beyond most plumbers.

True, but they'd have to be brain dead to get rid of the room stat, it's
only 2 wires. At worst they could have just used an old fashioned one and
turned the temp up and down as needed, still easier than going round all the
rads.

It sounds more like a rip off than incompetence, I wonder how much each of
those rad stats were charged at?

Rgds

Andy R

BillP wrote:

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done

these

days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.




If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.





Can you show me exactly where this is stated?

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.

Ther is no issue with teh boiler running continuously. Boilers stop when
their own internal stats detect the return flow is up to temperature.


I seen no reaosn to install flow switches unless too simply protect the
pump...but a bypass loop does that anyway. Also how does the system
detect the condition when a TRV has opened up? It can't unless teh pump
is switched on to check flow rate...

There seems to be an urban myth here.


With a TRV system, the idea is to pump more or less continuously, and
let the TRV's decide on demand. The boiler merely cuts in when the
return flow has dropped to the boiler stat level.

Use of TRV's with an overall zone stat makes them essentially useless.
Either they are still demanding heat when the main stat cuts out, or
they have shutdown before it itself does, in which case it never
does.... you cannot have a romm or area controlled by two stats on
essentally the same zone.

With all due respect, you and Christian are talking what appears to be
twaddle.

On Fri, 12 Dec 2003 16:05:30 +0000, The Natural Philosopher wrote:

BillP wrote:



If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.


Can you show me exactly where this is stated?

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.

How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."

Also page 19
"d) Boiler and hot water storage controls.
So that replacement boilers (other than solid
fuel boilers) and hot water vessels can achieve
reasonable seasonal efficiency, the work may
also need to include replacement of the time
switch or programmer, room thermostat, and
hot water vessel thermostat, and provision of a
boiler interlock and fully pumped circulation.
Section 3 of GPG 302 34 gives more advice on
how this can be done."

John Armstrong wrote:

On Fri, 12 Dec 2003 16:05:30 +0000, The Natural Philosopher wrote:


BillP wrote:



If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.


Can you show me exactly where this is stated?

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.


How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."


Well every boiler I have ever seen comes with a thermostatic switch to
do just that.

I can't find that in my slightly older (2000) building regs tho.



Also page 19
"d) Boiler and hot water storage controls.
So that replacement boilers (other than solid
fuel boilers) and hot water vessels can achieve
reasonable seasonal efficiency, the work may
also need to include replacement of the time
switch or programmer, room thermostat, and
hot water vessel thermostat, and provision of a
boiler interlock and fully pumped circulation.
Section 3 of GPG 302 34 gives more advice on
how this can be done."


Yes, but it doesn't say you have to set up a system of two suites of
thermostats essentially fighting each other.

On Fri, 12 Dec 2003 16:05:30 +0000, The Natural Philosopher
wrote:

BillP wrote:

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done

With a TRV system, the idea is to pump more or less continuously, and
let the TRV's decide on demand. The boiler merely cuts in when the
return flow has dropped to the boiler stat level.

Use of TRV's with an overall zone stat makes them essentially useless.
Either they are still demanding heat when the main stat cuts out, or
they have shutdown before it itself does, in which case it never
does.... you cannot have a romm or area controlled by two stats on
essentally the same zone.

With all due respect, you and Christian are talking what appears to be
twaddle.


FWIW I have a full TRV system (i.e. no rads without TRVs), with an
auto-bypass loop at the boiler, *and* a programmable room stat in the
hall.

The TRVs are set so that, in the evening, the rooms are each at the
desired comfort level - thereby fulfilling the aims of a full-TRV
system as you describe it.

However, the hall-stat is set (at 21C in the evening) to shut down the
boiler when all rooms are up to temperature.

In the morning we have the hall stat set to 19C, as we're rushing
around and don't like it too warm in the mornings. There's no way we
could do this without that stat in the hall, unless we went around and
altered the TRVs all the time.

We do get in the situation where some rooms are not up to temperature
and the hall stat shuts the boiler down - this is as you predict, so
against all advice I have fitted a TRV on the radiator in the hall
too. This I set a little cooler than we'd ideally like, so the hall is
the last to warm up - it needs heat "leaking" from other rooms to
finally hit 21.

It's a bit of a fudge, but I can't find a better way of doing it! I
suppose you might argue that that we might as well set the stat to 45C
in the evenings and let the TRVs do their job, which is fair enough,
but we still need the stat to achieve a lower temperature than the
TRVs would allow.

So, with all due respect you are talking what appears to be twaddle
:-) Well, partial twaddle maybe.




Tim Hardisty.
Remove HAT before replying

I can't find that in my slightly older (2000) building regs tho.

The requirement is new from the 2002 building regulations. I suspect you are
simply still thinking in terms of pre-2002 requirements.

How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."


Well every boiler I have ever seen comes with a thermostatic switch to
do just that.

No, the thermostatic switch is not enough. It must totally turn off and not
keep the primary circulating water hot. As every single gas/oil boiler in
existence has such a thermostatic device (or similar analogue modulating
control), why do you think they would mention room thermostats or flow
switches as interlock devices?

If the system you propose is installed, the boiler will operate (to heat
primary circulating water) even when all TRVs are closed and the hot water
cylinder is hot. This is not allowed. I'm afraid you appear to be in a
minority of one in insisting that an all TRV system is allowed without room
thermostat or flow switch.

Yes, but it doesn't say you have to set up a system of two suites of
thermostats essentially fighting each other.

Indeed. There are three methods proposed.

a) Install TRVs and a roomstat. You can balance and design the system such
that the TRV rooms heat up marginally quicker than the room thermostat
rooms. This ensures that the TRVs turn off before the room thermostat
engages the boiler interlock. This provides good temperature control in all
rooms.

b) Install a flow switch that determines that when no flow occurs through
the TRVs, the boiler is turned off, and the circulating water cools down.
This provides even better temperature control in all rooms.

c) Install a fully controlled zoned system (i.e. room thermostat/no TRV in
every room).

Christian.

It's a bit of a fudge, but I can't find a better way of doing it!

Set the TRV to full (preferably replace, so the radiator is lockshield both
ends). Then balance down the hall radiator using the lockshield so that it
warms up slowly and doesn't get very hot. Then, when the other radiators get
shut down via their TRVs, more water gets to the hall radiator. By the time
all TRVs have shut, the hall radiator gets the full force of the boiler,
heats the hall and the room stat shuts down.

I suppose you might argue that that we might as well set the stat to
45C in the evenings and let the TRVs do their job,

This would defeat the boiler interlock and make your system inefficient, as
the boiler will continue to short cycle, heating your primary water which
may lose heat into areas not required to be heated.

Christian.

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.

It needs one by law. A control interlock to shut off the burner when the
house is up to temp. Who fitted it? Tell him to get them back and fit one.


---
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Version: 6.0.548 / Virus Database: 341 - Release Date: 05/12/2003

"BillP" wrote in message
...

"stuart noble" wrote in message
...
My neighbour has just had a new Baxi combi installed. They've put TRVs
on
all the rads bar one and have ripped out the old room thermostat. Is
this
normal? I find being able to set that to 15 or so useful if you're
leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just
as
well there aren't any kids about. It looks as though you can adjust the
CH
temperature on the boiler but it's already below 50% on the scale.



If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.

It can have a flow switch on the system, but I doubt if there is one fitted.


---
--

Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.548 / Virus Database: 341 - Release Date: 05/12/2003

On Fri, 12 Dec 2003 17:04:07 -0000, "Christian McArdle"
wrote:

It's a bit of a fudge, but I can't find a better way of doing it!

Set the TRV to full (preferably replace, so the radiator is lockshield both
ends). Then balance down the hall radiator using the lockshield so that it
warms up slowly and doesn't get very hot. Then, when the other radiators get
shut down via their TRVs, more water gets to the hall radiator. By the time
all TRVs have shut, the hall radiator gets the full force of the boiler,
heats the hall and the room stat shuts down.

That would work, but the advantage of my approach is that the hall
rapidly gets close to temperature, then takes a long(er) while to get
to final temperature. This has the effect of making it seem to warm
quickly.

Your approach would result in the hall seeming colder for longer, but
would work.


Tim Hardisty.
Remove HAT before replying

"The Natural Philosopher" wrote in message
...
BillP wrote:

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs
on
all the rads bar one and have ripped out the old room thermostat. Is
this
normal? I find being able to set that to 15 or so useful if you're
leaving
the house unoccupied for a few days but maybe that's not how it's done

these

days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just
as
well there aren't any kids about. It looks as though you can adjust the
CH
temperature on the boiler but it's already below 50% on the scale.




If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.

Can you show me exactly where this is stated?

It isn't.

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.

It refers to it as a control interlock. Can be a flow switch. In short, a
device to switch out the burner when the house is up to temp. A boiler is
not allowed to cycle unnecessarily.

Ther is no issue with teh boiler running continuously. Boilers stop when
their own internal stats detect the return flow is up to temperature.

That is cycling - NOT ALLOWED.

I seen no reaosn to install ...

That is because you don't understand.

There seems to be an urban myth here.

Not so.

With a TRV system, the idea is to pump
more or less continuously, and
let the TRV's decide on demand.

Good idea.

The boiler merely cuts in when the
return flow has dropped to the boiler
stat level.

What if all rads have TRVs? Then the boiler cycles. So a flow switch is
necessary to cut out thre burner.

Use of TRV's with an overall zone stat
makes them essentially useless.

Not useless, just less effective. If the room stat is in the coolest part
of the house, usually the hall, and the rad is sized and balanced to give
the desired room temp, then if this room is satisfied then all the others
are. As it is the coolest room in the house it will demand heat before the
others, so the other room will not be cool.

With all due respect, you and Christian are talking what appears to be
twaddle.

'fraid not! It is you who are twaddling along.



---
--

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Version: 6.0.548 / Virus Database: 341 - Release Date: 05/12/2003

That would work, but the advantage of my approach is that the
hall rapidly gets close to temperature, then takes a long(er)
while to get to final temperature. This has the effect of
making it seem to warm quickly.

The problem with your system is that it requires a reasonably sentient being
to operate and adjust it, which makes it fine for someone such as yourself
who understands the interactions between the various valves and temperature
sensing devices and knows not to fiddle after it is set up.

For an installation by an engineer for your average spod with no
understanding on how central heating and TRVs work, it would be hopeless.
The first thing most people do with TRVs is set them to 30C when they feel
cold, as they think they are on/off/power switches.

Christian.

"The Natural Philosopher" wrote in message
...
John Armstrong wrote:

On Fri, 12 Dec 2003 16:05:30 +0000, The Natural Philosopher wrote:


BillP wrote:



If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.


Can you show me exactly where this is stated?

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.


How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."


Well every boiler I have ever seen comes with a thermostatic switch to
do just that.

I can't find that in my slightly older (2000) building regs tho.


Part L was this year me old chum.

Yes, but it doesn't say you have to set up a system of two suites of
thermostats essentially fighting each other.

It doesn't say that at all. It doesn't say let a boiler cycle on itself
either.


---
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"Tim Hardisty" wrote in message
...
On Fri, 12 Dec 2003 16:05:30 +0000, The Natural Philosopher
wrote:

BillP wrote:

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs
on
all the rads bar one and have ripped out the old room thermostat. Is
this
normal? I find being able to set that to 15 or so useful if you're
leaving
the house unoccupied for a few days but maybe that's not how it's done

With a TRV system, the idea is to pump more or less continuously, and
let the TRV's decide on demand. The boiler merely cuts in when the
return flow has dropped to the boiler stat level.

Use of TRV's with an overall zone stat makes them essentially useless.
Either they are still demanding heat when the main stat cuts out, or
they have shutdown before it itself does, in which case it never
does.... you cannot have a romm or area controlled by two stats on
essentally the same zone.

With all due respect, you and Christian are talking what appears to be
twaddle.


FWIW I have a full TRV system (i.e. no rads without TRVs), with an
auto-bypass loop at the boiler, *and* a programmable room stat in the
hall.

The TRVs are set so that, in the evening, the rooms are each at the
desired comfort level - thereby fulfilling the aims of a full-TRV
system as you describe it.

However, the hall-stat is set (at 21C in the evening) to shut down the
boiler when all rooms are up to temperature.

In the morning we have the hall stat set to 19C, as we're rushing
around and don't like it too warm in the mornings. There's no way we
could do this without that stat in the hall, unless we went around and
altered the TRVs all the time.

We do get in the situation where some rooms are not up to temperature
and the hall stat shuts the boiler down - this is as you predict, so
against all advice I have fitted a TRV on the radiator in the hall
too. This I set a little cooler than we'd ideally like, so the hall is
the last to warm up - it needs heat "leaking" from other rooms to
finally hit 21.

It's a bit of a fudge, but I can't find a better way of doing it! I
suppose you might argue that that we might as well set the stat to 45C
in the evenings and let the TRVs do their job, which is fair enough,
but we still need the stat to achieve a lower temperature than the
TRVs would allow.

So, with all due respect you are talking what appears to be twaddle
:-) Well, partial twaddle maybe.

No Tim, 100% twaddle!


---
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On Fri, 12 Dec 2003 17:21:20 -0000, "Christian McArdle"
wrote:

That would work, but the advantage of my approach is that the
hall rapidly gets close to temperature, then takes a long(er)
while to get to final temperature. This has the effect of
making it seem to warm quickly.

The problem with your system is that it requires a reasonably sentient being
to operate and adjust it, which makes it fine for someone such as yourself
who understands the interactions between the various valves and temperature
sensing devices and knows not to fiddle after it is set up.

For an installation by an engineer for your average spod with no
understanding on how central heating and TRVs work, it would be hopeless.
The first thing most people do with TRVs is set them to 30C when they feel
cold, as they think they are on/off/power switches.

OK - I agree with your reasoning.

Over and out :-)
Tim Hardisty.
Remove HAT before replying

In article ,
The Natural Philosopher wrote:
With a TRV system, the idea is to pump more or less continuously, and
let the TRV's decide on demand. The boiler merely cuts in when the
return flow has dropped to the boiler stat level.

Use of TRV's with an overall zone stat makes them essentially useless.
Either they are still demanding heat when the main stat cuts out, or
they have shutdown before it itself does, in which case it never
does.... you cannot have a romm or area controlled by two stats on
essentally the same zone.

Fine if you want the same temperature all the time the heating is on, but
most don't.

I have a programmable stat in the living room which has no TRVs. Every
other rad has. The house comes up to the morning temp set by a combination
of the room stat and TRVs - obviously the room with the stat mustn't be
the first to reach its set temperature - and when the later daytime lower
temp switches in the whole house drops pretty consistently, and maintains
that new temperature. Similarly with the higher evening temperature - and
much lower nighttime one if I leave it on 24 hours as I do in very cold
weather.

It's called balancing the system. ;-)

--
*A fine is a tax for doing wrong. A tax is a fine for doing well.

Dave Plowman London SW 12
RIP Acorn

In article , IMM abuse-
writes

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs on
all the rads bar one and have ripped out the old room thermostat. Is this
normal? I find being able to set that to 15 or so useful if you're leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just as
well there aren't any kids about. It looks as though you can adjust the CH
temperature on the boiler but it's already below 50% on the scale.

It needs one by law.
Another drama queen . . . . .
--
fred

Thanks to one and all for your comments.

"fred" wrote in message ...
In article , IMM abuse-
writes

"stuart noble" wrote in message
...

My neighbour has just had a new Baxi combi installed. They've put TRVs
on
all the rads bar one and have ripped out the old room thermostat. Is
this
normal? I find being able to set that to 15 or so useful if you're
leaving
the house unoccupied for a few days but maybe that's not how it's done
these
days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just
as
well there aren't any kids about. It looks as though you can adjust the
CH
temperature on the boiler but it's already below 50% on the scale.

It needs one by law.

Another drama queen . . . . .

Do you mean it doesn't?




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Christian McArdle wrote:

I can't find that in my slightly older (2000) building regs tho.


The requirement is new from the 2002 building regulations. I suspect you are
simply still thinking in terms of pre-2002 requirements.


How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."


Well every boiler I have ever seen comes with a thermostatic switch to
do just that.


No, the thermostatic switch is not enough. It must totally turn off and not
keep the primary circulating water hot. As every single gas/oil boiler in
existence has such a thermostatic device (or similar analogue modulating
control), why do you think they would mention room thermostats or flow
switches as interlock devices?



Exactly. Because you are a prat was the instant assumption....:-)


If the system you propose is installed, the boiler will operate (to heat
primary circulating water) even when all TRVs are closed and the hot water
cylinder is hot.


Er, but it DOESN'T DO THIS. The primary circulating water, being nice
and lagged, stays hot for a LONG time, and the boiler stat has
hysteresis in its thermostat, so it may take up to an hour before the
little tiddy bit of water looping around gets cool. IF you have the
system on, and it doesn't need ANY heat input in an hour from the rooms,
might I suggest you switch it off anyway?

It makes NO sense to have a house stat.

This is not allowed. I'm afraid you appear to be in a
minority of one in insisting that an all TRV system is allowed without room
thermostat or flow switch.


Nothing in the system I am proposing wastes heat, or short cycles the
boiler. It is merely - and without actually reading the regs in full
detail, I can't even be sure - a TECHNICAL INFRINGEMENT. Not something
that wastes power - which is after all the spirit and purpose of the
regulations.




Yes, but it doesn't say you have to set up a system of two suites of
thermostats essentially fighting each other.


Indeed. There are three methods proposed.

a) Install TRVs and a roomstat. You can balance and design the system such
that the TRV rooms heat up marginally quicker than the room thermostat
rooms. This ensures that the TRVs turn off before the room thermostat
engages the boiler interlock. This provides good temperature control in all
rooms.


Ad the average bozo can just about understand turning up the room TRV's
to get warm, and does so, and then calls in the plumber cos the rads are
cold. Right. Been there, done that.



b) Install a flow switch that determines that when no flow occurs through
the TRVs, the boiler is turned off, and the circulating water cools down.
This provides even better temperature control in all rooms.


And what, pray, turns the pump on again?



c) Install a fully controlled zoned system (i.e. room thermostat/no TRV in
every room).



Indeed. We would all like to do that...


Christian.

Christian McArdle wrote:

It's a bit of a fudge, but I can't find a better way of doing it!


Set the TRV to full (preferably replace, so the radiator is lockshield both
ends). Then balance down the hall radiator using the lockshield so that it
warms up slowly and doesn't get very hot. Then, when the other radiators get
shut down via their TRVs, more water gets to the hall radiator. By the time
all TRVs have shut, the hall radiator gets the full force of the boiler,
heats the hall and the room stat shuts down.


I suppose you might argue that that we might as well set the stat to
45C in the evenings and let the TRVs do their job,


This would defeat the boiler interlock and make your system inefficient, as
the boiler will continue to short cycle, heating your primary water which
may lose heat into areas not required to be heated.



(hint. I have done this for some considerable time. The boiler doesn't
short cycle at all. Only in the case of very poorly insulated CH pipes
and a fairly warm set of rooms, and very cold spaces through which the
pipes run [almost impossible to achieve together with fairly warm rooms]
do you get teh '5 minute burn, five minute idle' sort of cycle. You MAY
get this with a fully TRV'ed system with a bypass buit even then its
unlikley. The water has to cool down quiet a lot to overcome boiler stat
hysteresis, and in that time its almost certain that one or more rads
will have opened up the TRV's a tad and be calling for heat anyway. )


Christian.

IMM wrote:

"The Natural Philosopher" wrote in message
...

BillP wrote:


"stuart noble" wrote in message
...


My neighbour has just had a new Baxi combi installed. They've put TRVs

on

all the rads bar one and have ripped out the old room thermostat. Is

this

normal? I find being able to set that to 15 or so useful if you're

leaving

the house unoccupied for a few days but maybe that's not how it's done


these


days.
The rad without the TRV (in the bathroom) you could fry an egg on. Just

as

well there aren't any kids about. It looks as though you can adjust the

CH

temperature on the boiler but it's already below 50% on the scale.




If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.

Can you show me exactly where this is stated?


It isn't.


My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.


It refers to it as a control interlock. Can be a flow switch. In short, a
device to switch out the burner when the house is up to temp. A boiler is
not allowed to cycle unnecessarily.




What is wrong with letting the CH return stat do this?

That is the point.

I ran a system fuly TRV'ed with the house stat turned flat out for
several years. The boiler neither short cycled nor ran continuously. It
cut off when the TRV's had had enough. There was a single unregulated
radiator in a well insulated airing cupboard.

I have a system now that in part is functinally equivalent, in that I
have room stats on fan blown rads. Plus a few TRV equipped rads. The
pump runs continously, The water circulates continuously, the fans come
and go, and the boiler does the same. It burns a few minutes, and then
shuts down.

Every room is set to the temperature requiertd. I don't have to mess
with heat leaks - which anyway would never work, because there is no
simple place to put a zone stat on this little lot. Dowqnstais hall ae
on a different zone (UF) and upstairs halls/landings are unheated as
they take heat from teh UF system by convection.



Ther is no issue with teh boiler running continuously. Boilers stop when
their own internal stats detect the return flow is up to temperature.


That is cycling - NOT ALLOWED.


I beg your pardon. All boilers cycle under normal usage. They get the
water up to temperature in the primary HW or CH circuits, and then shut
down. That is what they are designed to do for gawds sake!




I seen no reaosn to install ...


That is because you don't understand.


I don't think YOU do then.




There seems to be an urban myth here.


Not so.


With a TRV system, the idea is to pump
more or less continuously, and
let the TRV's decide on demand.


Good idea.


The boiler merely cuts in when the
return flow has dropped to the boiler
stat level.


What if all rads have TRVs? Then the boiler cycles. So a flow switch is
necessary to cut out thre burner.


No, you are confuding 'cycle' with 'short cycle' and also if yopu read
back on all posts, I never said that all rads were TRV'ed without at
least a bypass loop. The point is that short cycling happens when there
is NO flow. With ANY flow the boiler cuts out, and the hystersis of teh
boiler stat means the water cools several degrees before the next burn
comes along to raise it again. Unless you have a stalled pump, that
takes several minutes and more likely up to half an hour.

How quickly it heats up again of course depends on boiler stat
hysteresis and how much water is actually circulating. Obviously if you
stick a bypass loop by the boiler its not a huge amount. However, in my
case a long pipe run to a small radiator in an airing cupboard was more
than enough to mean a 2-3 minute burn was required at the minimum. And
frankly, any house that has its heating on, and requires no heat input
for half an hour, is wrongly timed anyway. I have been sitting here for
the duration of typing this, and my boiler has not fired up, yet the
pump is running all the time in the evening.





Use of TRV's with an overall zone stat
makes them essentially useless.


Not useless, just less effective. If the room stat is in the coolest part
of the house, usually the hall, and the rad is sized and balanced to give
the desired room temp, then if this room is satisfied then all the others
are. As it is the coolest room in the house it will demand heat before the
others, so the other room will not be cool.


Ok, at what point will a system with all TRV'ws and a master stat become
exactly the same as a system with no stat and all TRV's?

Easy. When the stat is turned up beyind the ability of the TRV'd rads to
flip it.

Result, one user adjustable contol that all by itself, renders the house
essentially exactly the way I ran mine. Statless.

Guess why they have stats in the boilers chaps, and make them cycle...




With all due respect, you and Christian are talking what appears to be
twaddle.


'fraid not! It is you who are twaddling along.



No. I still don't see it.

On an ALL TRV'ed system, I'll buy that a poorly designed system equipped
with a very short bypass COULD in theory - but rarely in practice -
short cycle. It will NOT run the boiler continuously tho. If it does the
bloody thing wil explode.! Thats why teh boiler has its stat...
Equipping the house with a stat does NOTHING to remedy that in my
opinion. Either the stat is set too low and the TRV's never do their
work, or the stat is set too high, and might as well not be there at
all. Finding some arbitrary finely tuned position and temperature
setting for the stat is completely beyond the average home owner, and is
far more likely to result in over use of energuy as he rams the stat
open in frustration, and then faffs around with his TRV's.

A non statted sytem that detects a stalled pump is good, except how does
it detect a stalled pump when the pump is off? It can't. So instead of
boiler short cycling we have pump short cycling.

The answer os simple. All TRV's no ghouyse stat and one radiator that
is not TRV'ed that has sufficient thermal inertia and water capacity to
stop short cycling. Or simply put a bypass right across the longest pipe
run. Sure, the pipe run is contributing to heatinbg teh house, but the
situatin where th ehouse is warm enough, all rads are shutdown and teh
bozo still runs his heating every day all day seems rather remote.

Most users can cope with the 'its bloody hot today, sparrows are wilting
in teh park, I'll turn my central heating off'.

The iedal is obviously a separet zone in every room coupled back to the
pump and boiler. TRV's are almost that, the only difference is that you
have to rely on return temperature to tell the boiler its not needed
anymore.






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IMM wrote:


I can't find that in my slightly older (2000) building regs tho.



Part L was this year me old chum.



No, it wasn't. I have part L in 200 regulations. I assume its a
different part L - an updated one.

Dave Plowman wrote:

In article ,
The Natural Philosopher wrote:

With a TRV system, the idea is to pump more or less continuously, and
let the TRV's decide on demand. The boiler merely cuts in when the
return flow has dropped to the boiler stat level.


Use of TRV's with an overall zone stat makes them essentially useless.
Either they are still demanding heat when the main stat cuts out, or
they have shutdown before it itself does, in which case it never
does.... you cannot have a romm or area controlled by two stats on
essentally the same zone.


Fine if you want the same temperature all the time the heating is on, but
most don't.

I have a programmable stat in the living room which has no TRVs. Every
other rad has. The house comes up to the morning temp set by a combination
of the room stat and TRVs - obviously the room with the stat mustn't be
the first to reach its set temperature - and when the later daytime lower
temp switches in the whole house drops pretty consistently, and maintains
that new temperature. Similarly with the higher evening temperature - and
much lower nighttime one if I leave it on 24 hours as I do in very cold
weather.

It's called balancing the system. ;-)




Well in my house its even easier. If its cold upstairs I switch the
heating on. When I go into a room, I set the wall stats (TRV equivalent)
whilst I am in it, and when I am done I turn it down again.

Bedrooms that are in use are set to a preset setting that is
comfortable, as are bathhrooms.

If the weather is wearm, I switch the whole zone off. In between times I
have a timer that does the switching on and off for me.


The boiler does not short cycle. Neither is it always on (Except under
full demand when heating first comes on or severe winter weather, when
it can take a LONG tome for the underfloor to come up to temp...

Asd fars as I can tell the regulations merely say that you need some
system to stop teh boiler running continuously, and that is amply
provided for by a single unregulated branch in the CH system, and the
boiler stat itself.

On Fri, 12 Dec 2003 16:58:21 +0000, Christian McArdle wrote:

I can't find that in my slightly older (2000) building regs tho.

The requirement is new from the 2002 building regulations. I suspect you are
simply still thinking in terms of pre-2002 requirements.

How about page 16, paragraph 1.41
"b) Where it is proposed to effect control by
thermostatic radiator valves, a room thermostat
(or other device such as a flow switch) should
also be provided to switch off the boiler when
there is no demand for heating or hot water."


Well every boiler I have ever seen comes with a thermostatic switch to
do just that.

No, the thermostatic switch is not enough. It must totally turn off and not
keep the primary circulating water hot. As every single gas/oil boiler in
existence has such a thermostatic device (or similar analogue modulating
control), why do you think they would mention room thermostats or flow
switches as interlock devices?

If the system you propose is installed, the boiler will operate (to heat
primary circulating water) even when all TRVs are closed and the hot water
cylinder is hot. This is not allowed. I'm afraid you appear to be in a
minority of one in insisting that an all TRV system is allowed without room
thermostat or flow switch.

Yes, but it doesn't say you have to set up a system of two suites of
thermostats essentially fighting each other.

Indeed. There are three methods proposed.

a) Install TRVs and a roomstat. You can balance and design the system such
that the TRV rooms heat up marginally quicker than the room thermostat
rooms. This ensures that the TRVs turn off before the room thermostat
engages the boiler interlock. This provides good temperature control in all
rooms.

b) Install a flow switch that determines that when no flow occurs through
the TRVs, the boiler is turned off, and the circulating water cools down.
This provides even better temperature control in all rooms.

c) Install a fully controlled zoned system (i.e. room thermostat/no TRV in
every room).


AIUI in scenario (a) Only rooms which are
i) Less frequently used
ii) bedrooms
iii) Rooms with additional sources of heat.
Need to have TRVs

It is a very good idea to have the space in which the room stat is located
containing a _correctly_ sized radiator without TRV.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

On Fri, 12 Dec 2003 17:24:50 +0000, IMM wrote:



So, with all due respect you are talking what appears to be twaddle
:-) Well, partial twaddle maybe.

No Tim, 100% twaddle!


IMHO the above response is a concise example of the difference between a
respectful disagreement (by Tim Hardisty) and something else.

--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html

On Fri, 12 Dec 2003 21:45:29 +0000, The Natural Philosopher wrote:

IMM wrote:


I can't find that in my slightly older (2000) building regs tho.



Part L was this year me old chum.



No, it wasn't. I have part L in 200 regulations. I assume its a
different part L - an updated one.

2002 edition, came into force 1st April this year I think.

"Ed Sirett" wrote in message
news
On Fri, 12 Dec 2003 17:24:50 +0000, IMM wrote:



So, with all due respect you are talking what appears to be twaddle
:-) Well, partial twaddle maybe.

No Tim, 100% twaddle!


IMHO the above response is a concise example of the difference between a
respectful disagreement (by Tim Hardisty) and something else.

When someone is prattling twaddle, they must be told.


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"The Natural Philosopher" wrote in message
...

temperature on the boiler but it's already below 50% on the scale.
If the room stat has been removed, the installation does not meet the
minimum requirements of Part L building regs.

Can you show me exactly where this is stated?

It isn't.

My Part L building regulations have no mention of use of thermostats
beyond stating thet either TRV's or other thermostats should be used.

It refers to it as a control interlock. Can be a flow switch. In
short, a
device to switch out the burner when the house is up to temp. A boiler
is
not allowed to cycle unnecessarily.

What is wrong with letting the CH return stat do this?

Many people here have attempted to educate you on this point. You clearly
do not understand my old chum. So it is best you just take it as it is.

Best stop digging yourself into a deeper hole, my old chum.


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Many people here have attempted to educate you on this point. You clearly
do not understand my old chum. So it is best you just take it as it is.

Best stop digging yourself into a deeper hole, my old chum.



No one has actually pointed out where it is said that this is not allowable.

"The Natural Philosopher" wrote in message
...

Many people here have attempted to educate you on this point. You
clearly
do not understand my old chum. So it is best you just take it as it is.

Best stop digging yourself into a deeper hole, my old chum.

No one has actually pointed out where it is said that this is not
allowable.

My old snooty uni chum, it is best to stop now before it's embarrassing for
you.


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