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

lstar337

Sorry Malc, sorry Richard, you are wrong about this and Cardew is right.

It cannot be put any simpler than this:

Cardew wrote: »

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.

richardc1983

lstar337 wrote: »

Sorry Malc, sorry Richard, you are wrong about this and Cardew is right.

It cannot be put any simpler than this:

If the house is occupied and your out during the day from personal tests at home it is actually more energy efficient to let the weather comp and opentherm do its thing with a set back temp of 18C and system on temp of 20C.

Disabling those features and letting the house get 15C during the day and then asking the house to get back upto 20C your using probably about the same. But that is down to my own tests so how is it that my tests in my house show this? Because what is happening with modulating controls and opentherm etc is that rather than the house lose heat down to 15C during the day the boiler is just putting in the right amount of heat to maintain the desired set point so this keeps the heat loss at a minimum. What the boiler will then do to get it back upto 20C if you have the "system off" approach is fire at full pelt until the house is warm enough.

In my house its more economical for me to have the heating on 24/7 but with a night set back than it is to let the house get really cold then have the boiler running flat out to get it back upto temp - plus it is then not running in condensing mode.

richardc1983

https://www.fullcircuit.com/blog/proof-heating-247-can-be-cheaper

lstar337

richardc1983 wrote: »

Because what is happening with modulating controls and opentherm etc is that rather than the house lose heat down to 15C during the day the boiler is just putting in the right amount of heat to maintain the desired set point so this keeps the heat loss at a minimum. What the boiler will then do to get it back upto 20C if you have the "system off" approach is fire at full pelt until the house is warm enough.

OK, try to understand this.

The whole time your boiler is maintaining that heat, your house is losing heat, and the warmer it is the faster it loses it.

Imagine the heat as water dripping into a bucket.

My house has the heating off while I'm out so it drips out the heat in the house until the temperature equalises, then it stops. Lets say that it is a bucket full and it has taken an hour.

Your house (with the boiler maintaining) is not only dripping faster (greater temperature differential), but after the same hour the bucket is full and filling a second bucket, after another hour it is filling its third....and so on.

I return after 2 hours, put my single bucket back into the house and I'm back up to temperature. I lost a total of 1 bucket of heat and bought another to top back up.

What is happening at your house after 2 hours? You have lost two buckets and well on to filling your third.

Take it even further, I work a 9 hour day. After 9 hours I still only lost 1 bucket, how many have you lost?

I haven't even bothered to factor in your electricity costs from running the pump 24/7 compared to my 2 hours a day.

Conclusion, you have wasted more energy than me.

Cardew has it quite right. You wouldn't leave your heating on for a year while you were out, so don't leave it on for an hour.

lstar337

richardc1983 wrote: »

https://www.fullcircuit.com/blog/proof-heating-247-can-be-cheaper

Not seeing much proof there.

richardc1983

Not saying its cheaper but its less wear and tear on the boiler firing at full and from cold to hot. Its deffo negligible and I have not seen a diff in my bills but I note my boiler is less worn out.

lstar337

richardc1983 wrote: »

Not saying its cheaper but its less wear and tear on the boiler firing at full and from cold to hot. Its deffo negligible and I have not seen a diff in my bills but I note my boiler is less worn out.

Sorry Richard but that is exactly what you said. People claiming it is cheaper is the only thing I have issue with. Anybody can run their boiler however they like, if somebody told be how to run mine I would tell them to jog on!

Wear and tear? You said your boiler runs 24/7, is that more or less wear and tear than mine that runs just 2 hours a day?

And before it gets brought up, mine is always condensing. This is achieved by setting the output temperature so that the return is always low enough for condensing.

richardc1983

lstar337 wrote: »

Sorry Richard but that is exactly what you said. People claiming it is cheaper is the only thing I have issue with. Anybody can run their boiler however they like, if somebody told be how to run mine I would tell them to jog on!

Wear and tear? You said your boiler runs 24/7, is that more or less wear and tear than mine that runs just 2 hours a day?

And before it gets brought up, mine is always condensing. This is achieved by setting the output temperature so that the return is always low enough for condensing.

A mistype on my behalf.

Yeah it does run 24/7 - well I say the pump on it does unless the hall thermostat is met with its set point demand but the burner runs low. I've noticed less call outs from running it on low than from running it for 3 hours a day but it running its self into the ground to achieve that.

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.

You are rightly taking issue with people making incorrect claims re keeping boilers running v having timed heating periods.

I am taking issue with you claiming that you can keep a house at 21c all day long with the heating on for an hour at 6am and 30 mins at 6pm, in winter months. Just explain how your house can stay at 21c for ELEVEN hours without any heating !!!!! Impossible. Are you really expecting us to believe that there will be no heat loss for eleven hours ?

bumpercars99

bobstheboy wrote: »

You are rightly taking issue with people making incorrect claims re keeping boilers running v having timed heating periods.

I am taking issue with you claiming that you can keep a house at 21c all day long with the heating on for an hour at 6am and 30 mins at 6pm, in winter months. Just explain how your house can stay at 21c for ELEVEN hours without any heating !!!!! Impossible. Are you really expecting us to believe that there will be no heat loss for eleven hours ?

Meh I didn't make this claim but I heat my flat about an hour a night. I live in a flat, it has double glazing then a secondary glazing panel to keep out railway noise and hardly heat it at all. I'd turn it up if I was cold but get enough heat from other flats around being warm, heat from cooking and general heat from the boiler heating water to live comfortably. I don't keep track of the exact temperature but I don't often wear a jumper inside. I don't need the heating in the day particularly even if home at the weekend. Maybe my neighbour is just going crazy with the heating but I often wake up in the morning too warm...