CH slow to warm house

[Ihavenojob]

Just turn the boiler stat up, see what happens then. Radiator heat output is calculated with a input temperature of 75-80 degrees, so if your running at 55 you will never get the house warm quickly unless you fit oversized rads.You could also look into weather compensation, this basically involves an outdoor sensor which will adapt the power output from the boiler depending on the outdoor temperature.

 

[JohnD]

You have a small utility room with a (ludicrously) large radiator. The radiator is not very hot.

It may well have been deliberately balanced that way, otherwise the room would be roasting.

 

[stem]

no fault in particular except an oversized boiler.

Not really. As you have a combi, you wouldn't get much hot water with anything smaller.

 

[ntl142]

You have a small utility room with a (ludicrously) large radiator. The radiator is not very hot.

It may well have been deliberately balanced that way, otherwise the room would be roasting.

There's a lot of glass in that room, and to be fair it's open plan with the kitchen so the radiator serves both rooms. The kitchen is poorly insulated so I curtain off the rooms, and then yes the utility room is warm. As the kitchen is so poorly insulated I basically shut off that bit of the house and leave it to freeze... I've been putting off adding underfloor insulation for a while because it looks so grim under the floor!



I put the boiler CH temperature to max (80 I think) last night to see what happened. It cycled a lot less and the house got warm quicker (not amazing, but certainly an improvement). I turned it down to 60 and it was cycling a lot and not really warming up much. I guess at lower temperatures the return water is still warm enough to cycle it, whereas at higher temperatures the return water is not quite hot enough to make the boiler start cycling. Don't quite understand it, but it seemed to work. This also made the radiator that was cold at the bottom hot all over - perhaps the on/off cycling meant it never got enough water through it to get hot before it started to cool again. I'll experiment to try to find a balance between 65 and 80 that is reasonably efficient and reduces cycling.

Thanks again. Hopefully flushing the system helps improve things too.

 

[stem]

Turning the boiler thermostat up will increase the temperature of the water leaving it, so, it will take longer for the boiler to reach the higher temperature, meaning that it will burn for longer. As the radiators will now have a higher surface temperature, they will emit more heat than before, so your house will warm up more quickly, and because more heat is being emitted from the rads, the boiler will need to run for longer to replace the lost heat.

 

[ntl142]

Thanks for the explanation. I watched the temperature on the boiler increase when a demand for heat was made. It went from it's resting temperature of around 40 degrees upto 70 odd in under a minute and stabilised. I was expecting it to cycle off at that point, but it remained on. The display seems to show the flow temperature, not the return temperature.
I kept touching the flow and return pipes during the heating demand. As you'd expect the flow was very hot (presumably around 70 odd degrees) and the return was cool but warming. It wasn't until this warmed up that the boiler cycled off, by which point the house was warm and the radiators fully hot.

Anyway, it seems to be working better at a higher temperature, and I have a better understanding of it all - thanks.