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Purpose of valve betwen feed and return in central heating system
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Lieutenant Scott
Apr 1, 2012, 3:15:13 PM4/1/12
to
http://www.gasman.fsbusiness.co.uk/images/twopipe.jpg
My system is roughly as above (plus hot water and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
Whoever fitted the heating system put a pipe directly from flow to return (just to the right of the pump in the diagram above).
There's a gate valve on it with a red tap, which is switched off.
What is this for?
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http://petersphotos.com
Light travels faster than sound. This is why some people
appear bright until you hear them speak.
My system is roughly as above (plus hot water and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
Whoever fitted the heating system put a pipe directly from flow to return (just to the right of the pump in the diagram above).
There's a gate valve on it with a red tap, which is switched off.
What is this for?
--
http://petersparrots.com
http://petersphotos.com
Light travels faster than sound. This is why some people
appear bright until you hear them speak.
Lieutenant Scott
Apr 1, 2012, 3:15:54 PM4/1/12
to
http://www.gasman.fsbusiness.co.uk/images/twopipe.jpg
My system is roughly as above (plus hot water tank and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
My system is roughly as above (plus hot water tank and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
Andrew Gabriel
Apr 1, 2012, 3:36:35 PM4/1/12
to
In article <op.wb3o4schytk5n5@i7-940>,
It ensures there's still a flow path even if all the radiators
shut off, and/or if the arrangement of valves for selecting
heating/hot water have a mode where they're all closed.
It probably shouldn't be shut off, unless the system has been
modified since the original installation and no longer needs
it. You can get special bypass loop valves to use instead of
the gate valve which only open when the pump is trying to push
against a closed circuit, so they don't bleed any flow into the
return when there's a real demand for heat.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
"Lieutenant Scott" <n...@spam.com> writes:
> http://www.gasman.fsbusiness.co.uk/images/twopipe.jpg
>
> My system is roughly as above (plus hot water tank and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
>
> Whoever fitted the heating system put a pipe directly from flow to return (just to the right of the pump in the diagram above).
>
> There's a gate valve on it with a red tap, which is switched off.
>
> What is this for?
It's a crude bypass loop.
> http://www.gasman.fsbusiness.co.uk/images/twopipe.jpg
>
> My system is roughly as above (plus hot water tank and an extra radiator in the garage both with their own motorized valve, which are irrelevant to the question).
>
> Whoever fitted the heating system put a pipe directly from flow to return (just to the right of the pump in the diagram above).
>
> There's a gate valve on it with a red tap, which is switched off.
>
> What is this for?
It ensures there's still a flow path even if all the radiators
shut off, and/or if the arrangement of valves for selecting
heating/hot water have a mode where they're all closed.
It probably shouldn't be shut off, unless the system has been
modified since the original installation and no longer needs
it. You can get special bypass loop valves to use instead of
the gate valve which only open when the pump is trying to push
against a closed circuit, so they don't bleed any flow into the
return when there's a real demand for heat.
--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
Alan
Apr 1, 2012, 4:32:56 PM4/1/12
to
In message <op.wb3o3nbkytk5n5@i7-940>, Lieutenant Scott <n...@spam.com>
wrote
this position now. It provides a bypass path if all the radiators get
turned off.
A bypass valve is normally used these days
<http://www.free-instruction-manuals.com/pdf/p4734550.pdf>
--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk
wrote
>http://www.gasman.fsbusiness.co.uk/images/twopipe.jpg
>
>My system is roughly as above (plus hot water and an extra radiator in
>the garage both with their own motorized valve, which are irrelevant to
>the question).
>
>Whoever fitted the heating system put a pipe directly from flow to
>return (just to the right of the pump in the diagram above).
>
>There's a gate valve on it with a red tap, which is switched off.
>
>What is this for?
The gate valve is probably turned on a tiny bit but possibly seized in
>
>My system is roughly as above (plus hot water and an extra radiator in
>the garage both with their own motorized valve, which are irrelevant to
>the question).
>
>Whoever fitted the heating system put a pipe directly from flow to
>return (just to the right of the pump in the diagram above).
>
>There's a gate valve on it with a red tap, which is switched off.
>
>What is this for?
this position now. It provides a bypass path if all the radiators get
turned off.
A bypass valve is normally used these days
<http://www.free-instruction-manuals.com/pdf/p4734550.pdf>
--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk
Lieutenant Scott
Apr 1, 2012, 4:47:43 PM4/1/12
to
It's possible I shut it off years ago and forgot.
It used to be on a timer, and only limited by the thermostatic valves on the radiators, so it could block the pump without it.
But I added a room stat and opened the radiator valves fully, so there will never be a blocked pump.
I'll leave it shut for maximum power output.
Would a pump actually break with no flow?
If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
I'm not so think as you drunk I am...
Roger Mills
Apr 1, 2012, 4:52:40 PM4/1/12
to
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.
Andrew Gabriel
Apr 1, 2012, 5:04:21 PM4/1/12
to
In article <op.wb3tdtbuytk5n5@i7-940>,
turned off. You fit a stop valve instead (no knobs to turn).
> I'll leave it shut for maximum power output.
>
> Would a pump actually break with no flow?
No, but the boiler's heat exchanger would - it would overheat.
> If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
>
You need to look at the boiler's instructions. The minimum is usually
given as the minimum length of pipework around the bypass loop, so it's
enough to absorb the heat still passing through the heat exchanger
after the burner switches off, without causing the overheat stat to
trip or the water in the exchanger to boil. Some modern boilers don't
need an external bypass loop.
"Lieutenant Scott" <n...@spam.com> writes:
> On Sun, 01 Apr 2012 20:36:35 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>
>> In article <op.wb3o4schytk5n5@i7-940>,
>> "Lieutenant Scott" <n...@spam.com> writes:
>>> There's a gate valve on it with a red tap, which is switched off.
>>>
>>> What is this for?
>>
>> It's a crude bypass loop.
>> It ensures there's still a flow path even if all the radiators
>> shut off, and/or if the arrangement of valves for selecting
>> heating/hot water have a mode where they're all closed.
>>
>> It probably shouldn't be shut off, unless the system has been
>> modified since the original installation and no longer needs
>> it. You can get special bypass loop valves to use instead of
>> the gate valve which only open when the pump is trying to push
>> against a closed circuit, so they don't bleed any flow into the
>> return when there's a real demand for heat.
>
> Ah I see, thanks.
>
> It's possible I shut it off years ago and forgot.
>
> It used to be on a timer, and only limited by the thermostatic valves on the radiators, so it could block the pump without it.
>
> But I added a room stat and opened the radiator valves fully, so there will never be a blocked pump.
Ideally, remove the TRV in the room with the stat, so it can't get
> On Sun, 01 Apr 2012 20:36:35 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>
>> In article <op.wb3o4schytk5n5@i7-940>,
>> "Lieutenant Scott" <n...@spam.com> writes:
>>> There's a gate valve on it with a red tap, which is switched off.
>>>
>>> What is this for?
>>
>> It's a crude bypass loop.
>> It ensures there's still a flow path even if all the radiators
>> shut off, and/or if the arrangement of valves for selecting
>> heating/hot water have a mode where they're all closed.
>>
>> It probably shouldn't be shut off, unless the system has been
>> modified since the original installation and no longer needs
>> it. You can get special bypass loop valves to use instead of
>> the gate valve which only open when the pump is trying to push
>> against a closed circuit, so they don't bleed any flow into the
>> return when there's a real demand for heat.
>
> Ah I see, thanks.
>
> It's possible I shut it off years ago and forgot.
>
> It used to be on a timer, and only limited by the thermostatic valves on the radiators, so it could block the pump without it.
>
> But I added a room stat and opened the radiator valves fully, so there will never be a blocked pump.
turned off. You fit a stop valve instead (no knobs to turn).
> I'll leave it shut for maximum power output.
>
> Would a pump actually break with no flow?
> If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
>
given as the minimum length of pipework around the bypass loop, so it's
enough to absorb the heat still passing through the heat exchanger
after the burner switches off, without causing the overheat stat to
trip or the water in the exchanger to boil. Some modern boilers don't
need an external bypass loop.
Lieutenant Scott
Apr 1, 2012, 5:15:51 PM4/1/12
to
On Sun, 01 Apr 2012 22:04:21 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
> In article <op.wb3tdtbuytk5n5@i7-940>,
> "Lieutenant Scott" <n...@spam.com> writes:
>> On Sun, 01 Apr 2012 20:36:35 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>>
>>> In article <op.wb3o4schytk5n5@i7-940>,
>>> "Lieutenant Scott" <n...@spam.com> writes:
>>>> There's a gate valve on it with a red tap, which is switched off.
>>>>
>>>> What is this for?
>>>
>>> It's a crude bypass loop.
>>> It ensures there's still a flow path even if all the radiators
>>> shut off, and/or if the arrangement of valves for selecting
>>> heating/hot water have a mode where they're all closed.
>>>
>>> It probably shouldn't be shut off, unless the system has been
>>> modified since the original installation and no longer needs
>>> it. You can get special bypass loop valves to use instead of
>>> the gate valve which only open when the pump is trying to push
>>> against a closed circuit, so they don't bleed any flow into the
>>> return when there's a real demand for heat.
>>
>> Ah I see, thanks.
>>
>> It's possible I shut it off years ago and forgot.
>>
>> It used to be on a timer, and only limited by the thermostatic valves on the radiators, so it could block the pump without it.
>>
>> But I added a room stat and opened the radiator valves fully, so there will never be a blocked pump.
>
> Ideally, remove the TRV in the room with the stat, so it can't get
> turned off. You fit a stop valve instead (no knobs to turn).
I tend to leave all my doors open, so the whole house is at the same temperature.
> In article <op.wb3tdtbuytk5n5@i7-940>,
> "Lieutenant Scott" <n...@spam.com> writes:
>> On Sun, 01 Apr 2012 20:36:35 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>>
>>> In article <op.wb3o4schytk5n5@i7-940>,
>>> "Lieutenant Scott" <n...@spam.com> writes:
>>>> There's a gate valve on it with a red tap, which is switched off.
>>>>
>>>> What is this for?
>>>
>>> It's a crude bypass loop.
>>> It ensures there's still a flow path even if all the radiators
>>> shut off, and/or if the arrangement of valves for selecting
>>> heating/hot water have a mode where they're all closed.
>>>
>>> It probably shouldn't be shut off, unless the system has been
>>> modified since the original installation and no longer needs
>>> it. You can get special bypass loop valves to use instead of
>>> the gate valve which only open when the pump is trying to push
>>> against a closed circuit, so they don't bleed any flow into the
>>> return when there's a real demand for heat.
>>
>> Ah I see, thanks.
>>
>> It's possible I shut it off years ago and forgot.
>>
>> It used to be on a timer, and only limited by the thermostatic valves on the radiators, so it could block the pump without it.
>>
>> But I added a room stat and opened the radiator valves fully, so there will never be a blocked pump.
>
> Ideally, remove the TRV in the room with the stat, so it can't get
> turned off. You fit a stop valve instead (no knobs to turn).
I'd have to accidentally turn off six TRVs to cause a problem.
Mind you in the garage, only one (non thermostatic) valve. But its quite a number of turns, you couldn't knock it off by mistake.
>> I'll leave it shut for maximum power output.
>>
>> Would a pump actually break with no flow?
>
> No, but the boiler's heat exchanger would - it would overheat.
Surely the boiler would just cut out when it reached the desired water temperature and stay off, as it already does by cycling on and off to maintain the correct temperature in the flow pipe.
>> If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
>
> You need to look at the boiler's instructions. The minimum is usually
> given as the minimum length of pipework around the bypass loop, so it's
> enough to absorb the heat still passing through the heat exchanger
> after the burner switches off, without causing the overheat stat to
> trip or the water in the exchanger to boil. Some modern boilers don't
> need an external bypass loop.
Hang on a sec. If I switch off the heating at the point where the boiler is just about to stop burning, then no water is being pumped, and things don't break.
"You know that your landing gear is up and locked when it takes full power to taxi to the terminal."
Andrew Gabriel
Apr 1, 2012, 6:15:48 PM4/1/12
to
In article <op.wb3uophcytk5n5@i7-940>,
> Mind you in the garage, only one (non thermostatic) valve. But its quite a number of turns, you couldn't knock it off by mistake.
>
> Hang on a sec. If I switch off the heating at the point where the boiler is just about to stop burning, then no water is being pumped, and things don't break.
The boiler probably has a run-on timer for the pump, to keep it
going for a minute or two after the call for heat input has gone
and burner has gone out.
"Lieutenant Scott" <n...@spam.com> writes:
> On Sun, 01 Apr 2012 22:04:21 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>
>> In article <op.wb3tdtbuytk5n5@i7-940>,
>> "Lieutenant Scott" <n...@spam.com> writes:
>
> I tend to leave all my doors open, so the whole house is at the same temperature.
>
> I'd have to accidentally turn off six TRVs to cause a problem.
One day, someone else might be living there.
> On Sun, 01 Apr 2012 22:04:21 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>
>> In article <op.wb3tdtbuytk5n5@i7-940>,
>> "Lieutenant Scott" <n...@spam.com> writes:
>
> I tend to leave all my doors open, so the whole house is at the same temperature.
>
> I'd have to accidentally turn off six TRVs to cause a problem.
> Mind you in the garage, only one (non thermostatic) valve. But its quite a number of turns, you couldn't knock it off by mistake.
>
>>> If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
>>
>> You need to look at the boiler's instructions. The minimum is usually
>> given as the minimum length of pipework around the bypass loop, so it's
>> enough to absorb the heat still passing through the heat exchanger
>> after the burner switches off, without causing the overheat stat to
>> trip or the water in the exchanger to boil. Some modern boilers don't
>> need an external bypass loop.
>
> If it's just to remove that little bit of heat, I would imagine the flow through 10mm HEP would be sufficient.
Might be.
>>
>> You need to look at the boiler's instructions. The minimum is usually
>> given as the minimum length of pipework around the bypass loop, so it's
>> enough to absorb the heat still passing through the heat exchanger
>> after the burner switches off, without causing the overheat stat to
>> trip or the water in the exchanger to boil. Some modern boilers don't
>> need an external bypass loop.
>
> If it's just to remove that little bit of heat, I would imagine the flow through 10mm HEP would be sufficient.
> Hang on a sec. If I switch off the heating at the point where the boiler is just about to stop burning, then no water is being pumped, and things don't break.
going for a minute or two after the call for heat input has gone
and burner has gone out.
Lieutenant Scott
Apr 1, 2012, 6:56:44 PM4/1/12
to
On Sun, 01 Apr 2012 23:15:48 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
> In article <op.wb3uophcytk5n5@i7-940>,
> "Lieutenant Scott" <n...@spam.com> writes:
>> On Sun, 01 Apr 2012 22:04:21 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>>
>>> In article <op.wb3tdtbuytk5n5@i7-940>,
>>> "Lieutenant Scott" <n...@spam.com> writes:
>>
>> I tend to leave all my doors open, so the whole house is at the same temperature.
>>
>> I'd have to accidentally turn off six TRVs to cause a problem.
>
> One day, someone else might be living there.
It is customary to explain the heating system to the next owner. The previous owner did to me.
> In article <op.wb3uophcytk5n5@i7-940>,
> "Lieutenant Scott" <n...@spam.com> writes:
>> On Sun, 01 Apr 2012 22:04:21 +0100, Andrew Gabriel <and...@cucumber.demon.co.uk> wrote:
>>
>>> In article <op.wb3tdtbuytk5n5@i7-940>,
>>> "Lieutenant Scott" <n...@spam.com> writes:
>>
>> I tend to leave all my doors open, so the whole house is at the same temperature.
>>
>> I'd have to accidentally turn off six TRVs to cause a problem.
>
> One day, someone else might be living there.
Heating the garage may well have to be explained, I don't think many people do that.
>> Mind you in the garage, only one (non thermostatic) valve. But its quite a number of turns, you couldn't knock it off by mistake.
>>
>>>> If so, what is the minimum flow required for the average pump? I could have the situation of only having one 10mm HEP pipe flowing (the garage circuit).
>>>
>>> You need to look at the boiler's instructions. The minimum is usually
>>> given as the minimum length of pipework around the bypass loop, so it's
>>> enough to absorb the heat still passing through the heat exchanger
>>> after the burner switches off, without causing the overheat stat to
>>> trip or the water in the exchanger to boil. Some modern boilers don't
>>> need an external bypass loop.
>>
>> If it's just to remove that little bit of heat, I would imagine the flow through 10mm HEP would be sufficient.
>
> Might be.
>
>> Hang on a sec. If I switch off the heating at the point where the boiler is just about to stop burning, then no water is being pumped, and things don't break.
>
> The boiler probably has a run-on timer for the pump, to keep it
> going for a minute or two after the call for heat input has gone
> and burner has gone out.
In the event that all else has failed, and it seems tempting to actually read the instructions, don't panic: Get a bigger hammer!
ARWadsworth
Apr 2, 2012, 11:38:49 AM4/2/12
to
Lieutenant Scott wrote:
> On Sun, 01 Apr 2012 23:15:48 +0100, Andrew Gabriel
> On Sun, 01 Apr 2012 23:15:48 +0100, Andrew Gabriel
> > > I'd have to accidentally turn off six TRVs to cause a problem.
> >
> > One day, someone else might be living there.
>
> It is customary to explain the heating system to the next owner. The
> previous owner did to me.
I would have needed a seance to do that in the house I live in.
> >
> > One day, someone else might be living there.
>
> It is customary to explain the heating system to the next owner. The
> previous owner did to me.
--
Adam
Lieutenant Scott
Apr 2, 2012, 6:26:24 PM4/2/12
to
A chicken crossing the road is poultry in motion.
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