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Ask EU: thermostat confusion
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Kate B
Nov 30, 2022, 9:20:41 AM11/30/22
to
Dear umrats, I feel extremely dim at having got to my advanced age
without knowing the answer to this conundrum. In my defence I have to
say that I grew up in a house without central heating and when I lived
with my engineer husband we had this incredibly sophisticated controller
that had several sensors and a three-way valve, and dealt with
compensated flow and other arcane calculations. It worked extremely well
and although the house was large and drafty, managed to keep us warm.
Since the water temperature was controlled by the valve, all the
radiator thermostats were either set to max or closed, and the
controller thermostat was kept at around 20.5 (daytime, with various
time settings).
Now I am in a house half the size, terraced rather than detached, with a
new condensing boiler with what seem to me to be very primitive
controls, ie basically on or off. There is a central thermostat that I
keep between 17 and 19 (again various time settings), which is warm
enough. The radiator thermostats are mostly set to 2. But I seem to be
using a lot of gas. It's due for a service shortly, but in the meantime,
what is the most efficient way to manage radiator and central
thermostats? Keep the radiators either fully open or closed? Or keep
them at 2?
--
Kate B
without knowing the answer to this conundrum. In my defence I have to
say that I grew up in a house without central heating and when I lived
with my engineer husband we had this incredibly sophisticated controller
that had several sensors and a three-way valve, and dealt with
compensated flow and other arcane calculations. It worked extremely well
and although the house was large and drafty, managed to keep us warm.
Since the water temperature was controlled by the valve, all the
radiator thermostats were either set to max or closed, and the
controller thermostat was kept at around 20.5 (daytime, with various
time settings).
Now I am in a house half the size, terraced rather than detached, with a
new condensing boiler with what seem to me to be very primitive
controls, ie basically on or off. There is a central thermostat that I
keep between 17 and 19 (again various time settings), which is warm
enough. The radiator thermostats are mostly set to 2. But I seem to be
using a lot of gas. It's due for a service shortly, but in the meantime,
what is the most efficient way to manage radiator and central
thermostats? Keep the radiators either fully open or closed? Or keep
them at 2?
--
Kate B
Jim Easterbrook
Nov 30, 2022, 10:39:03 AM11/30/22
to
On Wed, 30 Nov 2022 14:20:40 +0000, Kate B wrote:
>
> Now I am in a house half the size, terraced rather than detached, with a
> new condensing boiler with what seem to me to be very primitive
> controls, ie basically on or off. There is a central thermostat that I
> keep between 17 and 19 (again various time settings), which is warm
> enough. The radiator thermostats are mostly set to 2. But I seem to be
> using a lot of gas. It's due for a service shortly, but in the meantime,
> what is the most efficient way to manage radiator and central
> thermostats? Keep the radiators either fully open or closed? Or keep
> them at 2?
Radiator thermostats should be set to the maximum temperature you want
>
> Now I am in a house half the size, terraced rather than detached, with a
> new condensing boiler with what seem to me to be very primitive
> controls, ie basically on or off. There is a central thermostat that I
> keep between 17 and 19 (again various time settings), which is warm
> enough. The radiator thermostats are mostly set to 2. But I seem to be
> using a lot of gas. It's due for a service shortly, but in the meantime,
> what is the most efficient way to manage radiator and central
> thermostats? Keep the radiators either fully open or closed? Or keep
> them at 2?
that room to be, so turn them right down in unused rooms. When all[1] of
the rooms are up to temperature the hot water coming out of the boiler
will go straight back into it and the boiler should shut off. When rooms
cool down their thermostats should open, allowing water through which will
return to the boiler cooler than when it left it, so the boiler will turn
back on again.
The central thermostat shuts the whole system off when the room it's in is
warm enough (even if the other rooms aren't). This room should not have a
radiator thermostat.
The boiler should adjust its gas consumption to the heat demand, using
more when all radiators are on and less when only a few are. This can
either be proportional (turning the gas up and down, and varying the air
flow to suit) or simple on-off.
[1] It is common for some radiators (typically in the bathroom) to be on
whenever the boiler is on so there is always some water circulating.
Pressure relief valves can also be used to achieve this.
--
Jim <http://www.jim-easterbrook.me.uk/>
1959/1985? M B+ G+ A L- I- S- P-- CH0(p) Ar++ T+ H0 Q--- Sh0
Kate B
Nov 30, 2022, 10:57:24 AM11/30/22
to
On 30/11/2022 15:39, Jim Easterbrook wrote:
> On Wed, 30 Nov 2022 14:20:40 +0000, Kate B wrote:
>>
>> Now I am in a house half the size, terraced rather than detached, with a
>> new condensing boiler with what seem to me to be very primitive
>> controls, ie basically on or off. There is a central thermostat that I
>> keep between 17 and 19 (again various time settings), which is warm
>> enough. The radiator thermostats are mostly set to 2. But I seem to be
>> using a lot of gas. It's due for a service shortly, but in the meantime,
>> what is the most efficient way to manage radiator and central
>> thermostats? Keep the radiators either fully open or closed? Or keep
>> them at 2?
>
> Radiator thermostats should be set to the maximum temperature you want
> that room to be, so turn them right down in unused rooms. When all[1] of
> the rooms are up to temperature the hot water coming out of the boiler
> will go straight back into it and the boiler should shut off. When rooms
> cool down their thermostats should open, allowing water through which will
> return to the boiler cooler than when it left it, so the boiler will turn
> back on again.
I'm not sure that this is happening. Does the whole system not just
> On Wed, 30 Nov 2022 14:20:40 +0000, Kate B wrote:
>>
>> Now I am in a house half the size, terraced rather than detached, with a
>> new condensing boiler with what seem to me to be very primitive
>> controls, ie basically on or off. There is a central thermostat that I
>> keep between 17 and 19 (again various time settings), which is warm
>> enough. The radiator thermostats are mostly set to 2. But I seem to be
>> using a lot of gas. It's due for a service shortly, but in the meantime,
>> what is the most efficient way to manage radiator and central
>> thermostats? Keep the radiators either fully open or closed? Or keep
>> them at 2?
>
> Radiator thermostats should be set to the maximum temperature you want
> that room to be, so turn them right down in unused rooms. When all[1] of
> the rooms are up to temperature the hot water coming out of the boiler
> will go straight back into it and the boiler should shut off. When rooms
> cool down their thermostats should open, allowing water through which will
> return to the boiler cooler than when it left it, so the boiler will turn
> back on again.
carry on until the central thermostat (in the hallway) reaches its set
temperature? But it seems that keeping them at 2 ought to be OK?
>
> The central thermostat shuts the whole system off when the room it's in is
> warm enough (even if the other rooms aren't). This room should not have a
> radiator thermostat.
>
> The boiler should adjust its gas consumption to the heat demand, using
> more when all radiators are on and less when only a few are. This can
> either be proportional (turning the gas up and down, and varying the air
> flow to suit) or simple on-off.
This I don't. How do you vary the air flow? I have turned down the water
> The boiler should adjust its gas consumption to the heat demand, using
> more when all radiators are on and less when only a few are. This can
> either be proportional (turning the gas up and down, and varying the air
> flow to suit) or simple on-off.
temperature but I don't see any way to turn the gas up and down.
>
> [1] It is common for some radiators (typically in the bathroom) to be on
> whenever the boiler is on so there is always some water circulating.
> Pressure relief valves can also be used to achieve this.
toasty warm most of the time.
--
Kate B
Jim Easterbrook
Nov 30, 2022, 11:08:45 AM11/30/22
to
On Wed, 30 Nov 2022 15:57:23 +0000, Kate B wrote:
> On 30/11/2022 15:39, Jim Easterbrook wrote:
>>
>> Radiator thermostats should be set to the maximum temperature you want
>> that room to be, so turn them right down in unused rooms. When all[1]
>> of the rooms are up to temperature the hot water coming out of the
>> boiler will go straight back into it and the boiler should shut off.
>> When rooms cool down their thermostats should open, allowing water
>> through which will return to the boiler cooler than when it left it, so
>> the boiler will turn back on again.
>
> I'm not sure that this is happening. Does the whole system not just
> carry on until the central thermostat (in the hallway) reaches its set
> temperature? But it seems that keeping them at 2 ought to be OK?
It carries on in that the pump will carry on circulating water through
> On 30/11/2022 15:39, Jim Easterbrook wrote:
>>
>> Radiator thermostats should be set to the maximum temperature you want
>> that room to be, so turn them right down in unused rooms. When all[1]
>> of the rooms are up to temperature the hot water coming out of the
>> boiler will go straight back into it and the boiler should shut off.
>> When rooms cool down their thermostats should open, allowing water
>> through which will return to the boiler cooler than when it left it, so
>> the boiler will turn back on again.
>
> I'm not sure that this is happening. Does the whole system not just
> carry on until the central thermostat (in the hallway) reaches its set
> temperature? But it seems that keeping them at 2 ought to be OK?
whatever radiators are still on, but if that's only a few of them the
water should return to the boiler not much cooler than when it left it. At
that point the boiler ought to shut off (or turn itself down) until it's
needed again.
Mike McMillan
Nov 30, 2022, 1:51:33 PM11/30/22
to
the finalised contract agreed and an air source heat pump fitted. Our
present boiler has very crude control; one knob to set temperature - for
hot water and radiators too. The boiler was set by BG when they installed
it 15 years ago and from what I have been able to glean from service
engineers; it will have been set to the default 16 kW/h position. This
apparently is how most of their engineers leave them - whether it is
correct, under or overpowered for the premises. The engineers do not bother
to adjust them to suit the need - after all, they ain’t paying the fuel
bills!!!! So, all this time, we have had a boiler that starts and stops
very frequently (every 5 minutes or so) and I have had to set the water
temperature so that the water reaches just short of 60 degrees for
legionnaires problems. I am hoping that the new, far more controllable
system will be far more economic to run than this regime has permitted.
Having said all that, many boilers do allow the temperatures to be set
independently for HW and space heating and the boiler might well have set
so that the capacity matches the need.
Our bathroom radiator is the one without a thermostat though I have placed
the Hive thermostat on the landing where there is no direct heat source as
the hall radiator is some 4 metres below and some lateral distance away on
a different wall. I have made many a work-around to get the Hive system to
work to a reasonable degree of satisfaction but I will not be using them
with the new emitters to be fitted for the 35 degree C system. In case
anyRat wants to know; the existing system is a BG badged Glow Worm 330
boiler.
--
Toodle Pip, Mike McMillan
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