setting up combi boiler and programmable thermostat

khampson

Hi, I've just had a programmable thermostat fitted to my boiler, now I was wondering what setting my boiler should be set, it was before and still is set at 60 degrees, is this the correct setting? It goes up to 80 degrees, so if i turn it up the hpuse will reach the programmable more quickly but will I be wasting energy? Or won't it matter? Only thing I can think of if the boiler temp is too low it will never reach the programmed temp meaning it could be potentially on all day? What are your thoughts?

Keith

HappyMJ

The higher you set the temperature the faster the house will reach the set temperature.....but what you want to do is set it so the heat loss from the radiators is enough so that the return temperature of the water is about 50C so that the boiler is condensing. Difficult to figure out. You could up it to 70C on very cold days and it will still condense. I don't think 80C will ever condense unless you have a lot of radiators and a very cold house with high heat loss. It really is guess work to get the balance right. However, if you get it wrong don't worry the cost for a few percentage points difference in efficiency isn't very much.

foreversummer

How can you tell if your boiler is condensing?

HappyMJ

foreversummer wrote: »

How can you tell if your boiler is condensing?

Good question and I'm just guessing here but seeing some water condensing and going down the condensate discharge pipe would indicate that it is condensing. All condensing boilers really do is take a bit of the waste heat out of the flue gases condensing the water vapour and transfer it into the returning water. The cooler the return water then the more heat that is transferred and the more economic the boiler runs. However, the longer it takes to heat the room then the more heat is lost cancelling out any savings. As soon as you start heating a room then the heat is starting to be lost straight away so if it takes 2 hours as opposed to 30 minutes to bring a room up to 21C then more heat is lost over the 2 hours. It's only a small amount so really it makes little difference.

foreversummer

Thank you HappyMJ. Well my boiler is set to 74 degrees and when it fires up there are plumes coming out of my flue! My condensate pipe is internal and it makes a 'ticking' sound regularly when the boiler is on so I guess that's the condensate going through it (presumably the condensate is warm and it causes the pipe to contact and expand slightly). So I guess all is good here. We are toasty and warm on this very cold day.