Room temperature never reaches desired thermostat temperature - what else can I do? 15 December 2022 at 9:21AM in Energy 42 replies 3.1K views

ireallycantyodel

I have a Glowworm Ultimate2 30c boiler with a Glowworm Climapro2 Thermostat. My issue is that the room temperature never reaches the desired thermostat temperature which is set to 18.5 c. As a result, the heating is on all day.

The flow temperature is set to 65 now to save some money (it was 80 but even when it was higher, the room temperature was never reached). The highest it goes is 14 degrees at the moment (on a frosty winter day) even when the heating is on all day.

I have recently bought some radiator reflector panels and am planning to install a shelf above the radiators to see if it makes a difference. Apart from the bathroom all radiators in the house have TRV's fitted and I am not sure if I should set them to max or turn them to low to let the thermostat do its thing? The radiators are warm to the touch throughout but never so hot that they are untouchable. The radiators in the biggest room are rather large/long so I don't think it's the radiator size but they are situated underneath the bay windows. It's an old council house and the roof is well insulated but the walls are cold to the touch (no cavities) but there is not much I can do about the latter at the moment. Would that undermine the room temperature or is there anything else I can do?

[Deleted User]

Putting TRVs on low would just turn off the radiators and leave the boiler running.  That's not going to help.

Dolor

Heating is simple physics. You set a temperature. This temperature will be reached when the heat entering the home equals the heat that the house is losing to the atmosphere.

Turning down the boiler flow temperature will increase the time needed to reach a set temperature. Indeed, the set temperature may never be reached.

It follows that:

Your boiler is too small for your home. Most are for an outside air temperature of Minus 7.

Your emitters are too small for the rooms that they are in. This could be down to radiator size.

Your heating system needs to be power flushed. Sludge causes radiator blockages and slow water flow.

Your home is poorly insulated.

Or a mix of all of the above.

saveallmymoney

For a first step, set the TRV to max (5?) in the room where the thermostat is.

bagand96

Have you tried bleeding the radiators?  If the flow rate is 65 then they should be hot to the touch (assuming the TRVs aren't turned down too low - leave them on max)

Mstty

Sorry to repeat what others have said but set trv to max (5 or 6 depending on your model).

See if the radiator gets very hot and if it gets hot at top and bottom. (If not bleed the radiator but not when pumping in scolding water set the trv to frost and belled when cool - do this for all radiators)

See how it heats up the room in question.

Reed_Richards

Have you tried bleeding the radiator?  It could be full of air so only a fraction of it is working.  You can usually tell if you have a problem because the top of the radiator will be colder than the bottom.

Edit: Oops, I missed the comment from @bagand96 - but great minds think alike.

chris_n

Dolor said:

Heating is simple physics. You set a temperature. This temperature will be reached when the heat entering the home equals the heat that the house is losing to the atmosphere.

Turning down the boiler flow temperature will increase the time needed to reach a set temperature. Indeed, the set temperature may never be reached.

It follows that:

Your boiler is too small for your home. Most are for an outside air temperature of Minus 7.

Your emitters are too small for the rooms that they are in. This could be down to radiator size.

Your heating system needs to be power flushed. Sludge causes radiator blockages and slow water flow.

Your home is poorly insulated.

Or a mix of all of the above.

It's a 30kW to the radiators boiler so unless this is a mansion it isn't too small even at -7. How big is the house, how many radiators, single or double radiators, are the radiators finned? Are the radiators all hot all over? A quick look at the controller suggests it may possibly have a modulating function designed to stop the temperature overshooting but I would concentrate on the radiators for now.

Alnat1

If the radiators are cooler or cold towards the bottom then they will probably be sludged up. This requires a power flush which is best done by professionals. They will clean out all the radiators and check they are balanced correctly.

ireallycantyodel

chris_n said:

Dolor said:

Heating is simple physics. You set a temperature. This temperature will be reached when the heat entering the home equals the heat that the house is losing to the atmosphere.

Turning down the boiler flow temperature will increase the time needed to reach a set temperature. Indeed, the set temperature may never be reached.

It follows that:

Your boiler is too small for your home. Most are for an outside air temperature of Minus 7.

Your emitters are too small for the rooms that they are in. This could be down to radiator size.

Your heating system needs to be power flushed. Sludge causes radiator blockages and slow water flow.

Your home is poorly insulated.

Or a mix of all of the above.

It's a 30kW to the radiators boiler so unless this is a mansion it isn't too small even at -7. How big is the house, how many radiators, single or double radiators, are the radiators finned? Are the radiators all hot all over? A quick look at the controller suggests it may possibly have a modulating function designed to stop the temperature overshooting but I would concentrate on the radiators for now.

First of all thanks so much for all these useful answers so far.

To answer your question Chris I had to look up what finned radiators are and I am still not quite sure tbh. The house is fairly small, just 2 bedrooms (the second bedroom is tiny but does get warm). The other bedroom is big-ish but only has a single radiator (it's also the coldest room). The radiator in the living room is a double radiator like this one but spreads across the bay window:



With regards to bleeding them, all radiators are the same temperature throughout so didn't think they need to be bled but I think it's something I can definitely try anyway.

The home is definitely not well insulated - at least the walls aren't. There is not much I can do at the moment as I am renting. But the roof is well insulated. I do feel a lot of heat goes out through the walls though.


Edit:

The flow temperature was reduced but it only affected the time it takes to heat up the house, the temperature hasn't changed so it's 14 degrees most of the time

FreeBear

ireallycantyodel said: The home is definitely not well insulated - at least the walls aren't. There is not much I can do at the moment as I am renting. But the roof is well insulated. I do feel a lot of heat goes out through the walls though.

Being a rented property, your hands are pretty much tied. Advice such as insulate and fit larger radiators are well outside what you can do without landlord consent. Going round plugging all the cold draughts and adding (easily removed) secondary glazing is about the limit of improvements.