Central Heating - Cheaper on all the time?

[footprints]

Is it cheaper to keep your heating on all of the time? This way the boiler doesnt have to re heat? Would it have to be kept on a low heat all of the time?

[Cardew]

This has been covered many many times on this forum.

It is not cheaper to keep the boiler on all the time. The longer your boiler is off, the lower your bill.

Do a search on this forum or read the Energy Saving Trust.

[simongregson]

Think of it like, would it be cheaper to leave the kettle on all the time?

The answer then seems obvious!

[footprints]

Great thanks for the responce. That does seem obvious...just people we know do it! Is there anyway of finding out how much more it cost?

[tomstickland]

You'll find that some people swear blind that it saves them money. They usually say "you don't waste energy heating a cold building". If you hear this ask them if they'd leave the heating on if they went away for six months, because then they'd not have to heat up a cold house when they got back.

[footprints]

good point..but I wonder if there are any factual ways of finding the answer out?

[Cardew]

The factual way of finding out the answer is to read and understand the laws of physics.

Or ask on this forum and get people who know what they are talking about to answer.

Or if you think the laws of physics are wrong -----

[tomstickland]

It's pretty simple TBH. The basic rules of thermodynamics, as emperically derived and accepted as true over centuries of research are required.

Heat flow is proportional to temperature difference between the heat source and the sink.

The rate of heat flow from the building is proportional to the temperature difference between it and the outside. If over a day the building is left to cool then the total amount of heat released into the outside world will be less than if the building is kept at an elevated temperature.

The total amount of heat lost per day will be proportional the summation of the time multiplied by temperature difference.

Turning the heating off when out will allow the house to cool and this will

[footprints]

Thanks..umm I dont think I understood all of that..

So should I let it re heat twice a day or keep it on all day?

[itsnotfair]

Never mind *footprints* some people just think they know everything. lol.
I'm with the leave it on low all the time brigade.

[espresso]

Originally Posted by itsnotfair

Never mind *footprints* some people just think they know everything. lol.
I'm with the leave it on low all the time brigade.

What's low and how high are your bills?

[Cardew]

Originally Posted by itsnotfair

Never mind *footprints* some people just think they know everything. lol.
I'm with the leave it on low all the time brigade.

Could that be because we have a rudimentary knowledge of the law of thermodynamics?

Why “never mind”? The OP asked a question and got the correct answer from several people – until your contribution of course!

Presumably it offends you that the OP is given the correct advice and won’t be following your practice?

Or perhaps you could back your advice with some sort of evidence.

Below is a extract from the FAQ on the Energy Saving Trust website – a Government backed organisation set up to advise on these matters – admittedly they probably think they ‘know it all’.

Perhaps you could explain why they are wrong. Could it be that a man in the pub told you?
Question

Is it more economical to leave my heating on 24hrs in the winter?



Answer

No. It is a common misconception that it is cheaper to leave your hot water and heating on all the time. Boilers use more power initially to heat water from cold, however the cost of this is greatly exceeded by the cost of keeping the boiler running all of the time.
The best solution is to programme your heating system so that it comes on when you need it most (possibly early morning and in the evening), and goes off when you don't need it (when you are out of the house or asleep). There are a range of controls that can be used and your heating engineer will be able to provide you with the most appropriate solution.
Depending on your circumstances it may be necessary to keep the heating on all day during winter but it will cost more than if you turn the heating off when you don't need it.

[footprints]

Thank-you Cardew for researching that for me..I think I have my answer now!!

But some people need to "chill out" abit and not get so stressed out! We aint all know it all's..we gotta learn from somewhere!

Anyway..I will be having a nice warm house this winter! Thanks!

[paulalawson]

I take it this goes for heating water too, i was always told it was cheaper to have it on all the time, heating and water, TYPICAL no wonder my bills are so high.
would be great to know

[tomstickland]

Originally Posted by itsnotfair

Never mind *footprints* some people just think they know everything. lol.
I'm with the leave it on low all the time brigade.

I don't really understand what you're trying to achieve here. I certainly don't think I "know it all", but thermodynamics is a subject I know a fair bit about.

There's no doubt that the total amount of heat flowing out from a house in a day will be higher if the house is kept warm all day compared with allowing it to cool for a couple of hours and then heating it back up.

[Cardew]

Originally Posted by paulalawson

I take it this goes for heating water too, i was always told it was cheaper to have it on all the time, heating and water, TYPICAL no wonder my bills are so high.
would be great to know

It applies for heating water as well - see the quote from the Energy saving trust in my earlier post.

As has been said many times, would you leave your kettle boiling all day as it is supposed to cost more to heat it up from cold?
That is the same principle; albeit the heat loss from a well lagged tank will not be high.

[paulalawson]

thankyou cardew,after being miss informed for over 8 years or even more, and having my water on constant i have changed my hot water to twice daily on the timer. we only have a small tank so hope we get enough hot water for what we need. i have put it on timer for 3 hours morning and again evening.i haven't put my heating on twice daily though, cause i am at home all day, and i dont like the temperature to drop below 18 degrees. too cold for me.I like it to come on at 20 degrees if needed in the dayand i turn it down to 18 at bed time. thanks again

[espresso]

Originally Posted by paulalawson

thankyou cardew,after being miss informed for over 8 years or even more, and having my water on constant i have changed my hot water to twice daily on the timer. we only have a small tank so hope we get enough hot water for what we need. i have put it on timer for 3 hours morning and again evening.i haven't put my heating on twice daily though, cause i am at home all day, and i dont like the temperature to drop below 18 degrees. too cold for me.I like it to come on at 20 degrees if needed in the dayand i turn it down to 18 at bed time. thanks again

You should not need it on for three hours morning and night. If you have a gas boiler, use that to heat your hot water all year round, as it is much cheaper than using electricity. A gas boiler can heat a tank full in half an hour if timed for morning an evening.

[paulalawson]

ok so we have a combination boiler, so half hour am and pm should be enough?

[espresso]

Originally Posted by paulalawson

ok so we have a combination boiler, so half hour am and pm should be enough?

Yes, if set for half an hour, it should heat up a tank full in less than that time.