Cheapest way to utilise a gas boiler

Spendalottie

Last winters gas bill was not far off £1000 and most of that was spent heating up bedrooms that are only used at night. Thus we've opened up our big old fireplace and are only using the central heating for an hour and a half in the evening to take the chill off the rooms. Is it cheaper to put the water on to heat at the same time (meaning the boiler is doing 2 jobs at the same time) or would it be the same cost if I put the hot water on twice?

macman

No, because the boiler doesn't 'do 2 jobs at once' for the same cost. To heat both requires it to burn more gas.
Heat escaping from the hot water tank will serve to warm the house, so is not directly lost, but this is fairly marginal.

Cardew

Spendalottie wrote: »

Last winters gas bill was not far off £1000 and most of that was spent heating up bedrooms that are only used at night.

Why didn't you switch off the radiators in unused bedrooms after you got up(and any other unused rooms for that matter).

It takes seconds and you can switch them back on an hour or so before you retire.