Hot Water and heating question

hlw1810

I hope this isn't too silly a question. I don't normally heat my water as we all have showers (electric) and the dishwasher & washing machine heat their own water.
I've got standard central heating that uses a gas boiler that also does the water if I turn it on.

I've just started to turn the heating on for an hour or so here or there now were getting frosts, and I wondered if I turned the hot water at the same time - will it use more energy to heat the water as the boiler's already on heating the radiators? It would be nice to have the luxury of a bit of hot water if it won't cost me anymore when I'm using the heating....

System

When i had a back boiler it just took longer to heat the water up with the heating on so am guessing it probz will be costing a little more

hlw1810

Thanks, it's not a back boiler though - just a normal gas central heating boiler in the kitchen on the wall.....

macman

Yes, of course if will cost you more. It's heating the water for the hot tank via a totally different circuit to the CH. The more hot water you heat, the more gas you burn, the more it costs.

hlw1810

macman wrote: »

Yes, of course if will cost you more. It's heating the water for the hot tank via a totally different circuit to the CH. The more hot water you heat, the more gas you burn, the more it costs.

Thankyou. Not knowing anything about central heating or how it works, I didn't know.

espresso

hlw1810 wrote: »

Thankyou. Not knowing anything about central heating or how it works, I didn't know.

However it is not likely to be a totally different circuit. Commonly the output from the boiler feeds a 3 port valve with 2 outputs, one to the central heating radiators and one to heat the hot water cylinder.

Think of the hot water cylinder like having an extra radiator or two turned on. Yes it will cost a little more to heat your hot water while the heating is on but you could simply check if it worth any small extra cost by taking meter readings and trying it for a week, taking the "the luxury of a bit of hot water" into consideration. If your hot water tank is well insulated it will not be heating the water up from cold.

Cardew

espresso wrote: »

Think of the hot water cylinder like having an extra radiator or two turned on.

It is surprising how many people on MSE think that if you have one radiator switched on, then it costs the same in running costs to have all the radiators in the property switched on. 'After all it is the same hot water that goes to all the radiators'

macman

And remember that any heat loss from the hot tank goes to warm the house anyway.
But using the DHW is not 'cost free'.