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Reverse circulation central heating?
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Gareth
Dec 17, 2011, 11:39:38 AM12/17/11
to
I posted a while ago about radiators heating up when the central heating is
turned off but just the hot water is turned on (conventional boiler).
I've realised that the radiators are also heating up - almost all of them -
when their thermostatic valve is switched off.
It seems too much of a coincidence that every thermostatic valve - about 8
of them - could be faulty.
Does this sound like a reverse circulation problem?
If so is there a way of fixing it without causing too much disturbance to
pipe work?
turned off but just the hot water is turned on (conventional boiler).
I've realised that the radiators are also heating up - almost all of them -
when their thermostatic valve is switched off.
It seems too much of a coincidence that every thermostatic valve - about 8
of them - could be faulty.
Does this sound like a reverse circulation problem?
If so is there a way of fixing it without causing too much disturbance to
pipe work?
Lieutenant Scott
Dec 17, 2011, 11:43:23 AM12/17/11
to
--
http://petersparrots.com
http://petersphotos.com
Top Tip. If someone shoves your feet in a fire, quickly put your head in a bucket of iced water. On average, you will be pretty comfortable.
harry
Dec 17, 2011, 12:27:04 PM12/17/11
to
It could be that a motorised valve may not be closing off properly.
thirty-six
Dec 17, 2011, 12:43:23 PM12/17/11
to
On Dec 17, 4:39 pm, "Gareth" <hotmail.com@dgareth_remove.com> wrote:
> I posted a while ago about radiators heating up when the central heating is
> turned off but just the hot water is turned on (conventional boiler).
>
> I've realised that the radiators are also heating up - almost all of them -
> when their thermostatic valve is switched off.
>
> It seems too much of a coincidence that every thermostatic valve - about 8
> of them - could be faulty.
>
> Does this sound like a reverse circulation problem?
Sounds like you are without a bypass loop in your heating circuit.
> turned off but just the hot water is turned on (conventional boiler).
>
> I've realised that the radiators are also heating up - almost all of them -
> when their thermostatic valve is switched off.
>
> It seems too much of a coincidence that every thermostatic valve - about 8
> of them - could be faulty.
>
> Does this sound like a reverse circulation problem?
Thermostatic radiator control valves do not necessarily have a
positive shut-off positon and those will lift given sufficient
pressure from the circulating pump.
>
> If so is there a way of fixing it without causing too much disturbance to
> pipe work?
the time, and control its actual output with a towel.
Gareth
Dec 17, 2011, 1:11:56 PM12/17/11
to
"thirty-six" wrote in message
news:37e3bc05-8359-421d...@s26g2000yqd.googlegroups.com...
Thanks guys for the replies - much appreciated.
This last comment about keeping the rad nearest the boiler on all the time
has made me remember something I had forgot.
When we moved in the previous occupant had left an instruction sheet with
the boiler saying one radiator must be left on full all the time (the one in
the bathroom nearest to the boiler). Why would this be?
You've said the same thing. Does opening that radiator reduce the pressure
flowing in to the other radiators?
news:37e3bc05-8359-421d...@s26g2000yqd.googlegroups.com...
This last comment about keeping the rad nearest the boiler on all the time
has made me remember something I had forgot.
When we moved in the previous occupant had left an instruction sheet with
the boiler saying one radiator must be left on full all the time (the one in
the bathroom nearest to the boiler). Why would this be?
You've said the same thing. Does opening that radiator reduce the pressure
flowing in to the other radiators?
harry
Dec 17, 2011, 2:54:04 PM12/17/11
to
>
> - Show quoted text -
There should be a bypass valve fitted to the heating circuit next to
the boiler. As radiator valves close down, this valve opens as the
pressure rises.
May be this hasn't been fitted.
This sort of thing.
http://www.screwfix.com/p/honeywell-straight-auto-bypass-valve-22mm/34127
hugh
Dec 17, 2011, 2:48:55 PM12/17/11
to
In message <4eecdb6c$0$2500$db0f...@news.zen.co.uk>, Gareth
<hotmail.com@dgareth_remove.com> writes
AIUI it is normal to have one radiator without a TRV, the one in the
room which contains the room thermostat.
However the OPs problem is that radiators are still heating up even when
the heating is switched off but the hot water is on. This suggests as
someone has already said that a motorised valve is not switching
properly.
--
hugh
<hotmail.com@dgareth_remove.com> writes
room which contains the room thermostat.
However the OPs problem is that radiators are still heating up even when
the heating is switched off but the hot water is on. This suggests as
someone has already said that a motorised valve is not switching
properly.
--
hugh
ARWadsworth
Dec 17, 2011, 3:12:33 PM12/17/11
to
thirty-six wrote:
>>
>> If so is there a way of fixing it without causing too much
>> disturbance to pipe work?
>
> Take the conrol head off the rad nearest the boiler, so it's on all
> the time, and control its actual output with a towel.
That is one of the most stupid comments I have read on this newsgroup.
>>
>> If so is there a way of fixing it without causing too much
>> disturbance to pipe work?
>
> Take the conrol head off the rad nearest the boiler, so it's on all
> the time, and control its actual output with a towel.
--
Adam
dennis@home
Dec 17, 2011, 5:17:30 PM12/17/11
to
"hugh" <hugh@[127.0.0.1]> wrote in message
news:AyocgIJn...@raefell.demon.co.uk...
> AIUI it is normal to have one radiator without a TRV, the one in the room
> which contains the room thermostat.
What is needed is an auto bypass valve.
thirty-six
Dec 17, 2011, 7:57:09 PM12/17/11
to
On Dec 17, 8:12 pm, "ARWadsworth" <adamwadswo...@blueyonder.co.uk>
wrote:
Explain your need for this ridiculous outburst. Forgot to take a pill?
wrote:
harry
Dec 18, 2011, 4:14:29 AM12/18/11
to
though.
thirty-six
Dec 18, 2011, 4:59:55 AM12/18/11
to
Moonraker
Dec 18, 2011, 5:28:28 AM12/18/11
to
you have these, remove one of the thermostats and place the cap on,
screwing down firmly, this will completely shut off the radiator.
Incidentally should you ever wish to take a radiator off without
draining the system do this other, wise turning off the valve (as is the
case with you) does not necessarily turn off the flow completely, even
if it does it may turn itself on in the dead of the night, I got caught
out this way once.
--
Residing on low ground in North Staffordshire
Dave Liquorice
Dec 18, 2011, 6:19:18 AM12/18/11
to
On Sat, 17 Dec 2011 22:17:30 -0000, dennis@home wrote:
>> AIUI it is normal to have one radiator without a TRV, the one in
the
>> room which contains the room thermostat.
>
> Typical bodge made by plumbers.
> What is needed is an auto bypass valve.
Which is another bodge on the bodge that didn't fit a room stat to
>> AIUI it is normal to have one radiator without a TRV, the one in
the
>> room which contains the room thermostat.
>
> Typical bodge made by plumbers.
> What is needed is an auto bypass valve.
prevent the boiler short cycling once the house is up to temperature.
--
Cheers
Dave.
JohnW
Dec 18, 2011, 8:08:30 AM12/18/11
to
On 18 Dec, 11:19, "Dave Liquorice" <allsortsnotthis...@howhill.co.uk>
wrote:
I thought the auto bypass valves were more to allow a sink of heat for
the boiler when the motorised valve closed, and would still be needed
even if one rad had no TRV, as there would be no circulation path for
the pump overrun.
John
wrote:
the boiler when the motorised valve closed, and would still be needed
even if one rad had no TRV, as there would be no circulation path for
the pump overrun.
John
geoff
Dec 18, 2011, 10:40:45 AM12/18/11
to
In message
<339405fa-94e1-4a9e...@z17g2000vbe.googlegroups.com>,
harry <harol...@aol.com> writes
Your post about how flame sensing works, for example
--
geoff
<339405fa-94e1-4a9e...@z17g2000vbe.googlegroups.com>,
harry <harol...@aol.com> writes
--
geoff
ARWadsworth
Dec 18, 2011, 3:34:07 PM12/18/11
to
CH:-)
--
Adam
ARWadsworth
Dec 18, 2011, 3:37:21 PM12/18/11
to
dennis@home wrote:
> "hugh" <hugh@[127.0.0.1]> wrote in message
> news:AyocgIJn...@raefell.demon.co.uk...
>
>> AIUI it is normal to have one radiator without a TRV, the one in the
>> room which contains the room thermostat.
>
> Typical bodge made by plumbers.
Another one to add to the book.
> "hugh" <hugh@[127.0.0.1]> wrote in message
> news:AyocgIJn...@raefell.demon.co.uk...
>
>> AIUI it is normal to have one radiator without a TRV, the one in the
>> room which contains the room thermostat.
>
> Typical bodge made by plumbers.
hugh was correct.
--
Adam
dennis@home
Dec 18, 2011, 5:50:52 PM12/18/11
to
"ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
news:jcliup$q64$1...@dont-email.me...
Nobody said hugh was wrong.
ARWadsworth
Dec 18, 2011, 6:01:45 PM12/18/11
to
Either learn how to reply to a post using English or carry on making
yourself look like a steaming great twat.
--
Adam
dennis@home
Dec 18, 2011, 6:35:16 PM12/18/11
to
news:jclrdf$f6p$1...@dont-email.me...
More proof that ARW can't read.
thirty-six
Dec 18, 2011, 7:59:11 PM12/18/11
to
On Dec 18, 8:34 pm, "ARWadsworth" <adamwadswo...@blueyonder.co.uk>
It's the workings of your mind I'm not clear about.
harry
Dec 19, 2011, 4:01:44 AM12/19/11
to
To work properly, the boiler needs a constant volume of water going
through it. The radiators/remainder of heating system needs a constant
pressure.
This almost enables these conflicting requirements to be met.
Dave Liquorice
Dec 19, 2011, 4:32:11 AM12/19/11
to
On Mon, 19 Dec 2011 01:01:44 -0800 (PST), harry wrote:
>>>> Typical bodge made by plumbers.
>>>> What is needed is an auto bypass valve.
>>>
>>> Which is another bodge on the bodge that didn't fit a room stat
to
>>> prevent the boiler short cycling once the house is up to
temperature.
>>
>>>> Typical bodge made by plumbers.
>>>> What is needed is an auto bypass valve.
>>>
>>> Which is another bodge on the bodge that didn't fit a room stat
to
>>> prevent the boiler short cycling once the house is up to
temperature.
>>
>> I thought the auto bypass valves were more to allow a sink of heat
for
>> the boiler when the motorised valve closed, and would still be
needed
>> even if one rad had no TRV, as there would be no circulation path
for
>> the pump overrun.
>
for
>> the boiler when the motorised valve closed, and would still be
needed
>> even if one rad had no TRV, as there would be no circulation path
for
>> the pump overrun.
>
> No, the bypass valve is not a bodge.
>
> To work properly, the boiler needs a constant volume of water going
> through it.
Only more modern low water content boilers. Our floor standing lump
>
> To work properly, the boiler needs a constant volume of water going
> through it.
of cast iron with 12 gallons of water in it doesn't care a two hoots
about being turned off at full chat.
You only need an auto bypass valve if the boiler needs pump over run
and there is no path for that flow due to a motorised valve under
control of a room stat or no rad without a TRV. Even with a motorised
valve if you have a HW cylinder and three port valve the HW cylinder
will provide the heat dump for any required pump over run.
A blanket "fit a an auto bypass valve" is a bodge in that some
systems do not require one, either because the boiler doesn't need
one or because there is a inherent heat dump available.
> The radiators/remainder of heating system needs a constant pressure.
--
Cheers
Dave.
dennis@home
Dec 19, 2011, 5:13:02 AM12/19/11
to
"Dave Liquorice" <allsortsn...@howhill.co.uk> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
>> The radiators/remainder of heating system needs a constant pressure.
>
> Why?
If you are unlucky it will make it noisy.
It also results in a lower temperature drop across the radiator, which makes
condensing operation more difficult and wastes energy.
An alternative is a variable head pump that slows down.
IMO the "you must have a radiator always on" is just because of the
inadequate control systems fitted.
If you only have one room stat then you lose all control if the radiator can
be turned off by another means.
If you turn the radiator off the heating will run when it isn't needed.
thirty-six
Dec 19, 2011, 5:19:27 AM12/19/11
to
On Dec 19, 9:32 am, "Dave Liquorice"
<allsortsnotthis...@howhill.co.uk> wrote:
>
> > The radiators/remainder of heating system needs a constant pressure.
>
> Why?
Only in that it makes balancing the sytem quicker.
>
> > The radiators/remainder of heating system needs a constant pressure.
>
> Why?
Dave Liquorice
Dec 19, 2011, 5:40:59 AM12/19/11
to
On Mon, 19 Dec 2011 02:19:27 -0800 (PST), thirty-six wrote:
>>> The radiators/remainder of heating system needs a constant
pressure.
>>
>> Why?
>
> Only in that it makes balancing the sytem quicker.
Which, when doing the balancing it will have, as all the TRV heads
>>> The radiators/remainder of heating system needs a constant
pressure.
>>
>> Why?
>
> Only in that it makes balancing the sytem quicker.
will be removed otherwise you'll end up chasing your arse as they
shutdown or open up.
--
Cheers
Dave.
Dave Liquorice
Dec 19, 2011, 5:48:17 AM12/19/11
to
On Mon, 19 Dec 2011 10:13:02 -0000, dennis@home wrote:
>>> The radiators/remainder of heating system needs a constant
pressure.
>>
>> Why?
>
> Because the water will flow faster and faster through the remaining
> path. If you are unlucky it will make it noisy.
"if" and "unlucky"...
>>> The radiators/remainder of heating system needs a constant
pressure.
>>
>> Why?
>
> Because the water will flow faster and faster through the remaining
> path. If you are unlucky it will make it noisy.
> It also results in a lower temperature drop across the radiator, which
> makes condensing operation more difficult and wastes energy.
like a bypass valve does if fitted when not required or without a
means to shutdown the boiler when the house is warm.
> IMO the "you must have a radiator always on" is just because of the
> inadequate control systems fitted.
understanding of the system(s). Starting with the fact the boiler
might not need pump overrun.
> If you only have one room stat then you lose all control if the radiator
> can be turned off by another means.
fingers winding the bypass pressure right up? One can't cater for
idiots...
> If you turn the radiator off the heating will run when it isn't needed.
boiler down when the house is warm.
--
Cheers
Dave.
dennis@home
Dec 19, 2011, 6:26:29 AM12/19/11
to
"Dave Liquorice" <allsortsn...@howhill.co.uk> wrote in message
news:nyyfbegfubjuvyypb...@srv1.howhill.co.uk...
> On Mon, 19 Dec 2011 10:13:02 -0000, dennis@home wrote:
>
>>>> The radiators/remainder of heating system needs a constant
> pressure.
>>>
>>> Why?
>>
>> Because the water will flow faster and faster through the remaining
>> path. If you are unlucky it will make it noisy.
>
> "if" and "unlucky"...
>
>> It also results in a lower temperature drop across the radiator, which
>> makes condensing operation more difficult and wastes energy.
>
> Are there an non-modulating condensing boilers? And waste energy just
> like a bypass valve does if fitted when not required or without a
> means to shutdown the boiler when the house is warm.
See comment at end.
>
>>>> The radiators/remainder of heating system needs a constant
> pressure.
>>>
>>> Why?
>>
>> Because the water will flow faster and faster through the remaining
>> path. If you are unlucky it will make it noisy.
>
> "if" and "unlucky"...
>
>> It also results in a lower temperature drop across the radiator, which
>> makes condensing operation more difficult and wastes energy.
>
> Are there an non-modulating condensing boilers? And waste energy just
> like a bypass valve does if fitted when not required or without a
> means to shutdown the boiler when the house is warm.
>
>> IMO the "you must have a radiator always on" is just because of the
>> inadequate control systems fitted.
>
> IMO "you must have a bypass valve" is just beacuse of inadequate
> understanding of the system(s). Starting with the fact the boiler
> might not need pump overrun.
waste energy.
>
>> If you only have one room stat then you lose all control if the radiator
>> can be turned off by another means.
>
> I take it you mean manually. On that vein what is to stop some fiddle
> fingers winding the bypass pressure right up? One can't cater for
> idiots...
pump.
>
>> If you turn the radiator off the heating will run when it isn't needed.
>
> Just like a system with a bypass valve and no means of shutting the
> boiler down when the house is warm.
Who said fitting other controls wasn't required?
thirty-six
Dec 19, 2011, 9:01:11 AM12/19/11
to
On Dec 19, 10:40 am, "Dave Liquorice"
After all radiators have been initially flow adjusted there is still a
need to go back and check that they are performing according to the
system design. A second adjustment is probable when an auto-bypass is
not fitted. When there is only a minor adjustment to be made after a
complete system check, then it may be assumed that the rest of the
system will remain within tolerance. The auto-bypass, and a preset
one is about 16quid, saves the need to even perform the first system
check after the initial adjustment.
need to go back and check that they are performing according to the
system design. A second adjustment is probable when an auto-bypass is
not fitted. When there is only a minor adjustment to be made after a
complete system check, then it may be assumed that the rest of the
system will remain within tolerance. The auto-bypass, and a preset
one is about 16quid, saves the need to even perform the first system
check after the initial adjustment.
www.GymRatZ.co.uk
Dec 19, 2011, 9:38:18 AM12/19/11
to
On 17/12/2011 16:39, Gareth wrote:
> I posted a while ago about radiators heating up when the central heating
> is turned off but just the hot water is turned on (conventional boiler).
>
> I've realised that the radiators are also heating up - almost all of
> them - when their thermostatic valve is switched off.
>
> It seems too much of a coincidence that every thermostatic valve - about
> 8 of them - could be faulty.
>
> Does this sound like a reverse circulation problem?
>
> I posted a while ago about radiators heating up when the central heating
> is turned off but just the hot water is turned on (conventional boiler).
>
> I've realised that the radiators are also heating up - almost all of
> them - when their thermostatic valve is switched off.
>
> It seems too much of a coincidence that every thermostatic valve - about
> 8 of them - could be faulty.
>
> Does this sound like a reverse circulation problem?
>
> If so is there a way of fixing it without causing too much disturbance
> to pipe work?
Even when one circuit is shut off water can conduct heat just because
> to pipe work?
it's water.
When our shop became a 2nd zone off the heating circuit in the flat
above they plumbed the return from the shop into the closest return from
the flat. When shop zone was off by zone valve the Myson hi-line shop
fan heater would still fire up sporadically by simple conduction of
water in the Flat's return line raising temp high enough to cause
internal thermostatic fan to trigger.
Plumber had to come back an run a new return line for shop zone right
back to boiler to sort the problem.
Perhaps balancing the radiators accurately to significantly reduce the
amount of water that has access to conduct heat back in from the return
might help rather than the usual idea of trying to let TRV's sort
everything out?
Cheers
Pete
--
http://www.GymRatZ.co.uk - Fitness+Gym Equipment.
http://www.bodysolid-gym-equipment.co.uk
http://www.trade-price-supplements.co.uk
http://www.water-rower.co.uk
harry
Dec 19, 2011, 2:42:56 PM12/19/11
to
On Dec 19, 10:13 am, "dennis@home" <den...@killspam.kickass.net>
wrote:
> "Dave Liquorice" <allsortsnotthis...@howhill.co.uk> wrote in message
I think the "always have a radiator on" myth comes from the days of
solid fuel boilers when there always had to be a convection heat sink
to stop overheating if a control problem/pump failure arose.
wrote:
> "Dave Liquorice" <allsortsnotthis...@howhill.co.uk> wrote in message
solid fuel boilers when there always had to be a convection heat sink
to stop overheating if a control problem/pump failure arose.
harry
Dec 19, 2011, 2:39:38 PM12/19/11
to
On Dec 19, 9:32 am, "Dave Liquorice"
> Dave.- Hide quoted text -
>
> - Show quoted text -
As the rad valves close off, the pressure rises. this tends to defeat
the action of (especially thermostatic) valves and can lead to noises
in the sytem.
Also the balancing of the system is unaffected by valves opening/
closing.
The bypass valve relieves this pressure.
It also allows a constant flow of water through the boiler. Reduced
flows can lead to hot spots in the boiler, sludge settlement and
reduced efficiency. There is an optimum flow for each boiler design.
All of the above is the main reason why all this stuff us pre-
installed inside the boiler cabinets these days.
>
> - Show quoted text -
As the rad valves close off, the pressure rises. this tends to defeat
the action of (especially thermostatic) valves and can lead to noises
in the sytem.
Also the balancing of the system is unaffected by valves opening/
closing.
The bypass valve relieves this pressure.
It also allows a constant flow of water through the boiler. Reduced
flows can lead to hot spots in the boiler, sludge settlement and
reduced efficiency. There is an optimum flow for each boiler design.
All of the above is the main reason why all this stuff us pre-
installed inside the boiler cabinets these days.
dennis@home
Dec 19, 2011, 3:48:06 PM12/19/11
to
"harry" <harol...@aol.com> wrote in message
news:f08a49cf-2698-49b6...@u5g2000vbd.googlegroups.com...
use.
ARWadsworth
Dec 19, 2011, 4:29:34 PM12/19/11
to
dennis@home wrote:
> "ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
> news:jclrdf$f6p$1...@dont-email.me...
>> dennis@home wrote:
>>> "ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
>>> news:jcliup$q64$1...@dont-email.me...
>>>> dennis@home wrote:
>>>>> "hugh" <hugh@[127.0.0.1]> wrote in message
>>>>> news:AyocgIJn...@raefell.demon.co.uk...
>>>>>
>>>>>> AIUI it is normal to have one radiator without a TRV, the one in
>>>>>> the room which contains the room thermostat.
>>>>>
>>>>> Typical bodge made by plumbers.
>>>>
>>>> Another one to add to the book.
>>>>
>>>> hugh was correct.
>>>
>>>
>>> Another typical ARW cockup!
>>> Nobody said hugh was wrong.
>>
>>
>> You thick cunt.
>>
>> Either learn how to reply to a post using English or carry on making
>> yourself look like a steaming great twat.
>
> More proof that ARW can't read.
That's rich coming from the window licker that cannot read a German Road
> "ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
> news:jclrdf$f6p$1...@dont-email.me...
>> dennis@home wrote:
>>> "ARWadsworth" <adamwa...@blueyonder.co.uk> wrote in message
>>> news:jcliup$q64$1...@dont-email.me...
>>>> dennis@home wrote:
>>>>> "hugh" <hugh@[127.0.0.1]> wrote in message
>>>>> news:AyocgIJn...@raefell.demon.co.uk...
>>>>>
>>>>>> AIUI it is normal to have one radiator without a TRV, the one in
>>>>>> the room which contains the room thermostat.
>>>>>
>>>>> Typical bodge made by plumbers.
>>>>
>>>> Another one to add to the book.
>>>>
>>>> hugh was correct.
>>>
>>>
>>> Another typical ARW cockup!
>>> Nobody said hugh was wrong.
>>
>>
>> You thick cunt.
>>
>> Either learn how to reply to a post using English or carry on making
>> yourself look like a steaming great twat.
>
> More proof that ARW can't read.
Atlas.
--
Adam
ARWadsworth
Dec 19, 2011, 4:48:20 PM12/19/11
to
not have anything to compare it with.
--
Adam
hugh
Dec 19, 2011, 5:37:43 PM12/19/11
to
In message <4eef0e2e$0$23390$c3e8da3$33a0...@news.astraweb.com>,
"dennis@home" <den...@killspam.kickass.net> writes
If you turn the radiator off your are a fuckwit and get what you
deserve.
--
hugh
"dennis@home" <den...@killspam.kickass.net> writes
deserve.
--
hugh
dennis@home
Dec 19, 2011, 5:56:20 PM12/19/11
to
"hugh" <hugh@[127.0.0.1]> wrote in message
relationship between the room stat and the radiator is.
0 new messages