Room temperature never reaches desired thermostat temperature - what else can I do?

ireallycantyodel

M0KBJ said:

ireallycantyodel said:

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?

Hi, let's see if we can help.

Is this a new issue for you, or has it performed like this for a long time?

I've done some digging and read the manual for your thermostat and your boiler.

Is the room thermostat in the best location? Here's an extract from the manual:



First note that the boiler manual (p12) says that the user can set the maximum flow temperature but if the weather compensation external sensor is used, the actual flow temperature will be set by the boiler.

I wonder if some of the settings have been fiddled with or poorly commissioned. A few things for you to check in the installer menu:

1. Check that the maximum permissible room temperature is set to 30C and the room correction factor is 0C.
2. Turn off the modulating mode for a day. (This is an energy-saving feature, so I'd recommend turning it on again later. But it will be helpful to know if the modulation is part of the issue).
3. Check and make a note of the heating curve gradient setting. If it's different from the factory setting, which is 1.6, try changing it to 1.6. (It's important to make a note because after a couple of days experimenting, you might want to return it to where it was).

I wouldn't be surprised if a poorly-chosen weather modulation curve is the issue at a time when the external temperatures are unusually cold. This cold spell may have revealed a poor set-up which you haven't noticed in other seasons.

oooh I found the settings!

So the curve is set to 2.0  ( I have now set it to 1.6) the outside T correction is 0 degrees but as I said I have no idea what that actually means

The modulation is already off, max temp set to 30 and lowest temp to 0. I am also not sure if we do have an external sensor to be fair although the settings for it seem to be accessible.

Scrounger

Out of interest, on the radiator nearest the room thermostat, set the TRV to max and at the other end of the rad pull off the cap and turn the (lockshield) valve anticlockwise half a turn.  You will need pliers or an adjustable spanner.

Check if that rad now gets hotter.  If so, repeat on the other rads.


Scrounger

Alnat1

I fold the bottom of my curtains so they sit on the window sill when closed and the heat can't get up behind them so much

ireallycantyodel

Aylesbury_Duck said:

Anything you can do to improve the insulation of that bay window?  Putting more insulation inside the void above it?  Gluing insulated panels to its ceiling and then fitting a new "false ceiling" to hide them?

We do have double glazing but I was wondering if adding one of those window films would help to create a triple glazing effect - however, the windows are pretty good, no condensation or anything. 

WHen it comes to insulation I really need to speak to the landlord, he is quite strict on adding any extras.

BUFF said:

ireallycantyodel said:

chris_n said:

Could you measure the radiators, and type then we can work out how many kW they can put out.

Have a look at https://www.heatandthings.com/what-is-the-difference-between-a-type-11-type-21-and-type-22-radiator/

The one in your picture looks like a type 21 (double radiator, single finned).
I think we can discount the boiler being undersized.

Right, finally found my tape measure:

The bedroom radiator is one like this and it's 255 cm long (I guess this is just another, slimmer version of the Type 11 ones because it has no visible fins)


The one in the living room, after checking, is a type 21 - Only one layer of fins but enclosed in two panels.

It's 130 cm long.

Aylesbury_Duck said:

ireallycantyodel said:

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

This might be part of the problem.  Bay windows are often poorly-insulated because they sit outside the normal property footprint.  If the roof of the bay isn't well-insulated, it'll be an obvious cold spot that your nice double radiator is struggling to overcome.  Can you box off the bay with some thermal curtains, or is the radiator literally inside the bay itself?

The radiator is right under the window unfortunately - so if I get curtains it will also cover the radiator

I am looking to install a shelf to sit right above the radiator though.

Get shorter curtains that don't drop to the floor over the radiator or the shelf that you said that you are planning to fit above the radiator.
You want to leave a reasonable amount of space (15cm+) between the top of the rad & the shelf to allow the convected air to flow up through the rad & out into the room.

Spoonie_Turtle said:

ireallycantyodel said:

chris_n said:

Could you measure the radiators, and type then we can work out how many kW they can put out.

Have a look at https://www.heatandthings.com/what-is-the-difference-between-a-type-11-type-21-and-type-22-radiator/

The one in your picture looks like a type 21 (double radiator, single finned).
I think we can discount the boiler being undersized.

Right, finally found my tape measure:

The bedroom radiator is one like this and it's 255 cm long (I guess this is just another, slimmer version of the Type 11 ones because it has no visible fins)


The one in the living room, after checking, is a type 21 - Only one layer of fins but enclosed in two panels.

It's 130 cm long.

Aylesbury_Duck said:

ireallycantyodel said:

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

This might be part of the problem.  Bay windows are often poorly-insulated because they sit outside the normal property footprint.  If the roof of the bay isn't well-insulated, it'll be an obvious cold spot that your nice double radiator is struggling to overcome.  Can you box off the bay with some thermal curtains, or is the radiator literally inside the bay itself?

The radiator is right under the window unfortunately - so if I get curtains it will also cover the radiator

We have that problem too in the downstairs rooms (external windows, not a whole bay like yours but recessed in an attempt to create that impression).  We've tried to get curtains that reach the sill and no lower; they've just arrived for the coldest room so we'll find out next week when we can get them fitted whether that plan worked.  We have thermal blinds already inside the recess but obviously curtains should be much better without the gaps.

We already have blinds installed so as a last resort I might look into thermal curtains to attach to the window but would need to create some space for that

ireallycantyodel

Scrounger said:

Out of interest, on the radiator nearest the room thermostat, set the TRV to max and at the other end of the rad pull off the cap and turn the (lockshield) valve anticlockwise half a turn.  You will need pliers or an adjustable spanner.

Check if that rad now gets hotter.  If so, repeat on the other rads.


Scrounger

Gotta get the pliers out tomorrow morning :-) 

chris_n

No harm in trying the lockshield valves but I still suspect your radiators are too small to heat the room quickly. Your living room one is about 1.8kW with a 70 degree input temp and the bedroom is about 1.6. I guess there are other radiators in the property but you haven't given any sizes.

ireallycantyodel

chris_n said:

No harm in trying the lockshield valves but I still suspect your radiators are too small to heat the room quickly. Your living room one is about 1.8kW with a 70 degree input temp and the bedroom is about 1.6. I guess there are other radiators in the property but you haven't given any sizes.

Sorry I didn't because the other three rooms (Kitchen, Bathroom and small bedroom) heat up fine. But I don't spend much time there. Do you need the sizes for those as well?

chris_n

It would be good to understand the total heat going into the house and how the floor areas of the rooms compare. It's also worth thinking about what the aspect of the rooms is, i.e. which rooms face north and which have more than one outside wall.

Boat_to_Bolivia

Alnat1 said:

I fold the bottom of my curtains so they sit on the window sill when closed and the heat can't get up behind them so much

I was going to say the same thing. Thick curtains certainly make a big difference in my experience.

born_again

Also make sure that pin in TRV is not stuck down.