Roughly how many kW does a boiler use when ticking over?

Pincher

matelodave wrote: »

It does take ages to get the house up to temperature from cold though so instead of turning it off we turn it down a bit (night setback) and can boost it if required to attain a faster warm up.

My Glow worm ClimaPro allows a choice of several profiles. If I want faster response time, I can choose a more "aggressive" profile. The compromise is, aggressive means higher output temperature during catchup, which reduces condensation. I just keep it between 16 and 18 degrees, so the output is around 50 degrees most of the time. Slow and steady, keep condensing.


If I let the house cool down, I will pay more because of the lower efficiency during catch-up. By letting it condense all the time, I get more heat per unit of gas burnt, but I burn more units by having the boiler on longer. Paid about £700 for gas last year, including cooking. £120 standing charge, so the gas part was only £580. I doubt it would make a huge difference if I did it the other way.

shortchanged_2

Sorry to clarify yes I was asking about gas power.

Thanks for all your answers, so it modulates as low as 5kw. So what I'm wondering is there any point in using a gas fire at all or would it be cheaper to just the turn the thermostat down in the daytime while the weather is cold.

matelodave

We are all electric, heating, hot water etc etc. and our average non heating use (but including hot water) averages about 3500kwh a year.

Hot water & heating are supplied via an airsource heatpump.

Our max energy demand was in 2012 when we used 8600kwh = about 5100 for heating.
In 2103 we used 8000kwh = 4500kwh for heating and this year we should be just under 6000kwh = 2500kwh for heating - mainly due to the extremely mild weather and some more tweaking (optimising) of the controls.

matelodave

shortchanged wrote: »

Sorry to clarify yes I was asking about gas power.

Thanks for all your answers, so it modulates as low as 5kw. So what I'm wondering is there any point in using a gas fire at all or would it be cheaper to just the turn the thermostat down in the daytime while the weather is cold.

It depends on how good your insulation is, what sort of controls you've got, where they are situated and how you use the house. Just using thermostats, timers and TRVs can save you 50% over the cost of an uncontrolled system.

Even though it modulates down to 5kw if you are heating the whole house and it's losing 10kwh then the boiler will produce 10kw whereas if you are just sitting in the room with the gas fire and don't mind the rest of the house getting cold then a 3kw gas fire will only use 3kw as it's only heating one room.

If your thermostat is in the same room as the gas fire then by turning the fire on you'll shut down the heating in the rest of the house.
There is probably no advantage in heating bedrooms or the bathroom all day if you aren't in them so by turning the rads off or TRVs down in those rooms you'll save energy by reducing your heating demand. You just have to remember to turn them down in the morning when you've finished in there and to turn them back up an hour or so before you go to bed.

In the end it's all trial and error, you ideally want enough heat in the rooms that you are using at the time you are using them and to reduce the amount of heat when you don't need it.

Programmable thermostats can help by adjusting the room temperatures to specific times to suit your demand - there are electronic TRV heads which can do the same or you could even go the whole hog and get something like the EvoHome system which enable you to zone each room and control them all from your smartphone or tablet/laptop.