Central Heating Running Costs

[stocktonlad]

Sorry if this is a really stupid question.

We have a combi boiler that feeds 3 double, and 4 single radiators.

Are we using the same amount of gas when all radiators are on, compared to when only one or two are on.

I have always thought it doesnt matter how many radiators you have, your gas usage when running would be the same, cos all your doing is heating hot water and pumping it round the system.

Please correct me if I'm wrong.

Many Thanks

John

 

[macfudd]

In general you are correct,but be aware the more radiators you have on the more water you are heating.Therefore the boiler will stay on for longer,using more gas.

 

[picbits]

The more radiators you have, the more heat you're outputting from them and the more energy/gas the boiler takes to heat them.

On the other hand, if you had a 25 square meter room which was well insulated and heated it up to 20 degrees with a single radiator, it would take the same (roughly) amount of energy/gas as if you had 2 radiators in the same room.

Don't forget the idea of a radiator is to "get rid" of (or radiate/convect) heat into the room, this heat has to come from somewhere which is the boiler.

 

[picbits]

On the other hand .......

We have a 4 bedroom house.

My kids only come round on alternate weekends

If I turned off their radiators in their rooms when they weren't over (i.e. 12 out of 14 days) and kept their doors shut then I would save in gas from not heating up their rooms. I would therefore save a reasonable amount from not heating "empty space"

However if I left their doors open then their rooms would be heated by the rest of the house heating system regardless of if their radiators were on or off. This would cost about the same as leaving the radiators on.

 

[fatplumber]

Modern boilers modulate and they cut down the amount of gas they use according to demand. Old boilers rely on a thermostat and cut out when the boiler temperature reaches a set point. The more heat you require, i.e. the colder it is and or the more radiators you are heating then the more gas you are using.

 

[bengasman]

...My kids only come round on alternate weekends

If I turned off their radiators in their rooms when they weren't over (i.e. 12 out of 14 days) and kept their doors shut then I would save in gas from not heating up their rooms. I would therefore save a reasonable amount from not heating "empty space"

However if I left their doors open then their rooms would be heated by the rest of the house heating system regardless of if their radiators were on or off. This would cost about the same as leaving the radiators on.

Spot on, provided the other radiators have enough spare capacity to actually heat those unheated rooms to the same temperature; if not, you would save gas as the average temperature in the house would be lower than before.

 

[bengasman]

...We have a combi boiler that feeds 3 double, and 4 single radiators.

Are we using the same amount of gas when all radiators are on, compared to when only one or two are on.

I have always thought it doesnt matter how many radiators you have, your gas usage when running would be the same, cos all your doing is heating hot water and pumping it round the system...

You are hereby corrected