Will a 28kw Boiler use more gas than a 24kw one

[men8ifr]

Will a 28kw Boiler use more gas than a 24kw one if I'm using less than 24kw.

I'm just thinking of having a boiler installed and a larger one may give extra capacity to heat a garage or loft in the future (not needed now) but if I have a larger boiler will it use more gas (or maybe even less) if the full 28kw is not needed.

This is just a bit of an example of sizes I think my 3 bedroom house would need a 24kw boiler so a 28 or 32 kw may be able to also heat a garage or loft (I guess).

On the (very) same subject how important is it to get the right boiler in terms of energy efficiency?

 

[mickyg]

its important to size your boiler correctly for efficiency and to prevent cycling when in operation. A 3 bed house on average needs 10-16kw. There are lots of online calculators where you can work it out.

 

[men8ifr]

So an oversized boiler will in fact use more gas - a bit like having a 4L V8 in a car but only pottering around town it's going to use more petrol than a 1l car...

 

[men8ifr]

And cycling is the boiler switching on and off all the time? Don't new combi boilers adjust the size of the flame?

 

[mickyg]

And cycling is the boiler switching on and off all the time? Don't new combi boilers adjust the size of the flame?

the word your looking for is modulate and yes they do, but the bigger the boiler the bigger its min modulation rate will be. Anyway, you didnt say it was a combi. A combi should be sized for the hot water requirements,

 

[men8ifr]

OK thanks, so the minimum modulation (kw) is important then.

 

[mickyg]

OK thanks, so the minimum modulation (kw) is important then.

its not essential but it helps.