How much gas does your boiler use in the first hour of use?

Benny2020

So when it is flat out from cold my old non condensing boiler uses 12.3/11.2 and 9.6 kwh in the first hour on settings 5,4 and 3 on my 1 to 6 settings?
Is this a lot compared to new boilers?
After the first hour it reduces a lot, to be clear this is all before the house reaches its set temperature.

[Deleted User]

I have a 24kW Worcester Bosch GreenStar boiler. This is my 30 minute usage for this morning except for the first bar which is for 15 mins as my boiler comes out at minute 45. If you take bars 2 and 3 then my boiler used about 10kW in an hour (10kWh) at a flow temperature of 65C.

Benny2020

Ok so my old boiler is not that bad then?

QrizB

Benny2020 said:

Ok so my old boiler is not that bad then?

You're not really comparing like-with-like but no, it probably isn't too bad.

kimp22

Does that mean that it takes more kwh when first putting heating on and then drops abit. I put my heating on at 8pm and it was taking a penny per minute on prepayment meter. Since then the thermostat has been on and off but still used about £2.50 in that time and includes a bath. Trying to figure out how much its costing for a few hours use. 

Thanks
Kim

Benny2020

When you first put your boiler on it uses lots of gas to get the water up to temperature after that it "modulates" meaning it cuts in and out to maintain that temperature so uses less gas.

Benny2020

So how long did it run for that £2.50p?

northernsoul

Vaillant 837 condensing boiler 28kw.
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Boiler set at 75C flow , house start temp 12.5C , outside temp 4C , used 16.1kw in first hour raising house temp to 16C. Used 7.6kw in 2nd hour.
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Boiler set at 70C flow , house start temp 11C , outside temp 5C , used 14.3kw in first hour raising house temp to 15C. Used 6.3kw in 2nd hour.
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Boiler set at 60C flow , house start temp 11C , outside temp -2C , used 13.3kw in first hour raising house temp to 13.5C. Used 7kw in 2nd hour.
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Boiler set at 62C flow , house start temp 12C , outside temp 3C , used 11.6kw in first hour raising house temp to 15C. Used 5.9kw in 2nd hour.