MegaSack DRAW - This year's winner is user - rgwb
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Q1. If I have a modern boiler and TRVs on all the radiators, can I just whack the room stat up to something like 40deg and let the TRVs control the heat in each room?
Q2. When the stat kicks in currently, there's what sounds like the switching of a valve in/near the boiler and the pump still runs for a couple of minutes. I assume that this is some sort of 'run-on' function to run water through the boiler to cool the hot bits a bit, a bit like they have on electric showers?
Q1 Yes, probably not the most efficient way to run CH though.
Q2 Yes
I would say:
1 - No, the pump might end up pumping against a closed circuit, which might upset it a bit. You might also damage the heat exchanger.
2 - Yes, I think my pump does run on for a minute after the zzzz sound from the valve.
Q1 - No, because the radiator in the same room as the stat shouldn't have a TRV on it to prevent the TRV and the room stat from working against each other so this room will be boiling.
q2 - The pump runs on to keeping circulating the already hot water round the system to allow the heat to escape from the radiators
Cheers all. Any reason that our pump has started making a 'significantly louder than normal' noise when running on, but is fine when it's in the 'heating' mode? It's less then three years old.
Q1 - No, because the radiator in the same room as the stat shouldn't have a TRV on it to prevent the TRV and the room stat from working against each other so this room will be boiling.
The stat is a portable/wireless one. All the rads have TRVs.
No, the pump might end up pumping against a closed circuit, which might upset it a bit. You might also damage the heat exchanger.
Heat exchanger has a temp cut out to prevent this. All modern pumps are resistance sensing so back off the pressure as the TRVs close off one by one.
Once the returning water temp goes above a set threshold the boiler switches off the gas, and the after the over-run delay, it shuts off the pump.
IHN - I also added an external temperature sensor to ours. It genuinely does seem to vary the radiator water temp and boiler working out when to switch on or off in advance. Cost £22 to add, and IIRC most continental systems would not be without one.
The stat is a portable/wireless one. All the rads have TRVs.
Then the room where you choose to have the stat should have the TRV set to wide open.
I also added an external temperature sensor to ours.
We have a frost sensor on it, cos it's in the garage, so it will come on of it's own accord when it gets very cold. Is that the same thing?
To repeat my (other) question though - any reason that our pump has started making a 'significantly louder than normal' noise when running on, but is fine when it's in the 'heating' mode? It's less then three years old.
Maybe it just sounds louder when the boiler isn't running to mask the noise?
Nah, it's definitely louder, to the point where MrsIHN said "is there a car outside?", cos that's what it sounded like, and it's only started in the last week.
To repeat my (other) question though - any reason that our pump has started making a 'significantly louder than normal' noise when running on, but is fine when it's in the 'heating' mode? It's less then three years old.
Possibly a solenoid is shutting off first, so it's fighting a closed circuit when over running. You should be able to hear the solenoid close as they have a motor which winds back when they close, so you hear a whirring noise for a few seconds as it closes.
In the system there should be at least one radiator without a TRV as they can get stuck shut. Granted as most people say a modern boiler should sense the pressure and not run the pump against a closed circuit but better safe than sorry. Our non TRV'd radiator is in the bathroom.
we had that once - but thermostat was directly above the radiator and so we had to set thermostat to "surface of the sun" just to stop it from cutting the boiler and leaving the rest of the house cold all the timeThen the room where you choose to have the stat should have the TRV set to wide open.
In the system there should be at least one radiator without a TRV as they can get stuck shut. Granted as most people say a modern boiler should sense the pressure and not run the pump against a closed circuit but better safe than sorry.
You've still got the heat exchanger over temp cut out. Even if that fails, you have to boil the system dry before you melt anything. Boilers are pretty safe....
IHN. We have this. No idea why it gets louder after the valve has switched. Always done it.
Is that the same thing?
No.
Ours and is outdoor thermometer, and boiler 'learns' how house responds to heat input and changing temps outdoors.