Energy myth-busting: Is it cheaper to have heating on all day?

bobstheboy

lstar337 wrote: »

Nobody said you should be cold. I heat for an hour at 6am and 30 minutes at about 6pm and the house is 21c+ all day long.

That seems incredible. In fact unbelievable.

Of course you haven't said which month - July ?

lstar337

bobstheboy wrote: »

That seems incredible. In fact unbelievable.

Of course you haven't said which month - July ?

Most of last winter, though I did add on an extra 30 minutes during the colder days. House is A rated for insulation though.

The point is that it is completely possible to keep warm and have timed heating periods. My example is an extreme, but its possible in a lot of homes.

robotrobo

lstar337 wrote: »

Most of last winter, though I did add on an extra 30 minutes during the colder days. House is A rated for insulation though.

The point is that it is completely possible to keep warm and have timed heating periods. My example is an extreme, but its possible in a lot of homes.

Being pensioners & at home all day we have the heating on for at least 16 hours a day , the bungalow still does not get really hot and my wife is always complaining its still cold !, so i tell her to put another cardigan on and do a bit of jogging on the spot.
But seriously it can be a bit of a danger !, so the last one to bed as the job of extinguishing the candle as we dont want to die in bed.

juliebunny

Well thanks for the intel on the radiator covers, I've wanted to get these for ages to posh up a bit of a shabby house so I'm gonna go for it. I'm in a terrace, so the house holds heat pretty well. I'm in the school of keeping the thermostat to a steady heat, boiler set to low, 24/7 but this is based on a cost benefit analysis of keeping my elderly sick cats warm. One vet trip would just about wipe out any savings from letting them get cold.........!

lstar337

Nobody has said people shouldn't have the heating on 24/7 if they want to, that is every bodies individual choice.

It is only when people come on here and try to claim that it saves money that it becomes an issue.

It is simply not possible, so nobody should do it for money saving purposes.

If you find it costs very little more to have it on 24/7 and it makes you more comfortable, then go for it if you can spare the little extra cost.

Do what is comfortable for you, just don't claim it saves money.

malc_b

lstar337 wrote: »

Nobody has said people shouldn't have the heating on 24/7 if they want to, that is every bodies individual choice.

It is only when people come on here and try to claim that it saves money that it becomes an issue.

It is simply not possible, so nobody should do it for money saving purposes.

If you find it costs very little more to have it on 24/7 and it makes you more comfortable, then go for it if you can spare the little extra cost.

Do what is comfortable for you, just don't claim it saves money.

Actually it is possible, given the right circumstances to save money. I show the maths and physics for this here. One key assumption is that you have a condensing boiler as the majority will have. A condensing boiler is more efficient when used at low power. So although 24/7 heating uses more heat, all be it not as much as you might think (see here for the maths), the fact that the boiler runs more efficiently can overall use less gas which at the end of day is what we're interested in, £££, not heat loss.

richardc1983

juliebunny wrote: »

Well thanks for the intel on the radiator covers, I've wanted to get these for ages to posh up a bit of a shabby house so I'm gonna go for it. I'm in a terrace, so the house holds heat pretty well. I'm in the school of keeping the thermostat to a steady heat, boiler set to low, 24/7 but this is based on a cost benefit analysis of keeping my elderly sick cats warm. One vet trip would just about wipe out any savings from letting them get cold.........!

Avoid radiator covers, as a facilities manager any sites I come across with them end up getting them removed as they slow down the heat transfer from the radiators and reduce the airflow so much that the room is cold and takes forever to warm up. They do not keep the room warmer for longer. Radiators should not be covered up by covers or furniture etc.

You will also lose the radiant effect that makes radiators pleasant. AVOID at all costs. See below, but even with a cover with plenty of air gaps you will lose the radiant heating sun effect.

Another point to make is that with you saying you keep your system always on but at a low flow temp you will find your covers will be reducing the heat output so will have to put the flow temp up higher. I would suggest tidying up the existing radiators and making them look presentable rather than covering them.

RADIATOR COVERS
Q What are your views on fitting radiator covers? I would like to do so from the aesthetic point of view, but am concerned about what the impact might be on the heating efficiency.

If properly designed, with large air gaps at high and low level, a radiator cover should not interfere with the heat transfer from the radiator to the room, as there will be a flue effect of air being drawn through it. But a poorly designed or DIY radiator cover, relying only on the perforations in a sheet of decorative MDF or hardboard, might not work so well.

richardc1983

malc_b wrote: »

Actually it is possible, given the right circumstances to save money. I show the maths and physics for this here. One key assumption is that you have a condensing boiler as the majority will have. A condensing boiler is more efficient when used at low power. So although 24/7 heating uses more heat, all be it not as much as you might think (see here for the maths), the fact that the boiler runs more efficiently can overall use less gas which at the end of day is what we're interested in, £££, not heat loss.

Agreed, with controls such as weather compensation and opentherm that are designed to reduce the flow temp to keep the boiler "always on" to just meet demand from the heat loss of the house it is more efficient to keep it ticking over with modulating controls as apposed to firing it up from cold and the system using lots more gas to get to where it is. Done right you can save money and I have experienced this myself at home by controlling the flow temp of the boiler.

Cardew

richardc1983 wrote: »

Agreed, with controls such as weather compensation and opentherm that are designed to reduce the flow temp to keep the boiler "always on" to just meet demand from the heat loss of the house it is more efficient to keep it ticking over with modulating controls as apposed to firing it up from cold and the system using lots more gas to get to where it is. Done right you can save money and I have experienced this myself at home by controlling the flow temp of the boiler.

Here we go again!

I will put this simply for non-technical readers

The heat loss from a body(a room or house in this case) will depend on the difference between the room temperature and the outside temperature. So to keep a room at 20C while 0C outside it will lose heat at the rate of xxx watts. The standard of insulation is irrelevant for this discussion, better insulation simply means a slower rate of heat loss.

The lower the temperature in the room(say 18C) means that it will lose heat at a lower rate(while outside is still 0C. So dropping the room temperature saves money.

Now there is no argument that a CH boiler is more efficient if it is in condensing mode and with a weather compensator to keep the water temperature and flow optimum. So if you wish to keep the room at 20C that is the way to proceed.

However that is not the aim of CH for most people. We want the heating on in the morning, then let it lower whilst we are out at work(or working in the house). The heating up again in the evening, and off, or much lower, at night whilst in bed.

It is this statement from above that is so misleading.

is more efficient to keep it ticking over with modulating controls as apposed to firing it up from cold and the system using lots more gas to get to where it is.

That is frankly incorrect. Using the analogy given many times on MSE I would ask this question.

If you were leaving the house for, say, 2 years would you leave the heating on at 20C for that 2 years because it would use lots more gas to get back to 20C when you returned.

How about 1 year? 1 month? 1 week? 1 day? 1 hour? at which point do the laws of physics not apply?

Applying the same argument, you would leave a pan of water or a kettle simmering because it would use a lot more gas to bring it back to boiling after you had let it cool.

Any new readers should go back to Post#1 and read the same arguments again and again.

lstar337

richardc1983 wrote: »

You will also lose the radiant effect that makes radiators pleasant. AVOID at all costs. See below, but even with a cover with plenty of air gaps you will lose the radiant heating sun effect.

In spite of their name, radiant heat from radiators is minimal. They mostly work through convection.