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

wantanswers

HappyMJ wrote: »

From the time you leave home to go to work/school to the time you arrive back home.

Stay at home parents should have the heating on all day as they are actually getting a benefit from the heat.

To me this is quite easy to compare. Do the timed method Monday-Friday when everyone is out then leave the heating on all day on Saturday and Sunday when everyone is home. Read the meter every morning at the same time such as when you leave home and you should have a good idea on how much more it costs to have it on all day and set to the same temperature.

I don't mean to be disrespectful Happymj, but I would like to hear it from MSE, just so I know what hours to start monitoring from, then all of us who are interested are working from a level playing field as far as hours go.

Frankl

Some years ago I did a survey for British Gas where they monitored my gas usage over a two year period.
From this study I found that it cost only a few pence more to have the heating on all day and be comfortable.
You must remember that the walls of a house are like a big storage radiator and when you turn the heating off the walls cool down as they release the heat. When you turn the heating back on the walls have to absorb a lot of the heat being transmitted by the radiators and the house will only begin to feel warm once the walls are once again warm.

HappyMJ

wantanswers wrote: »

I don't mean to be disrespectful Happymj, but I would like to hear it from MSE, just so I know what hours to start monitoring from, then all of us who are interested are working from a level playing field as far as hours go.

Who is MSE?

wantanswers

HappyMJ wrote: »

Who is MSE?

Sorry about that (MSE) i should have said it would be good to hear from the person who posted the question at the top of the page ie

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

Sorry about that Happymj.

Anyway is it fair to assume "all day" is say from 7am until 10pm (programmer set on time)?

HappyMJ

wantanswers wrote: »

Sorry about that (MSE) i should have said it would be good to hear from the person who posted the question at the top of the page ie

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

Sorry about that Happymj.

Anyway is it fair to assume "all day" is say from 7am until 10pm (programmer set on time)?

It's an article. It's not a question. This thread is it's here to discuss the article and the points raised MSE will not post futher comments in it. I would say all day is only when you are out of the house. Normally the debate is comparing 2 timed periods morning and evening compared to just leaving it on all day. You can pick your own times it doesn't really matter...if you turn the heating off even for a couple of hours then you will save money (not a huge amount but there are savings). The temperature won't drop much over a couple of hours and the timer can be set to come on a half hour before you come back home again so the house will be warm by the time you get home. The walls won't be cold and the fabric of the house won't cool down too much.

wantanswers

HappyMJ wrote: »

It's an article. It's not a question. This thread is it's here to discuss the article and the points raised MSE will not post futher comments in it. I would say all day is only when you are out of the house. Normally the debate is comparing 2 timed periods morning and evening compared to just leaving it on all day. You can pick your own times it doesn't really matter...if you turn the heating off even for a couple of hours then you will save money (not a huge amount but there are savings). The temperature won't drop much over a couple of hours and the timer can be set to come on a half hour before you come back home again so the house will be warm by the time you get home. The walls won't be cold and the fabric of the house won't cool down too much.

Fair enough then.

tgroom57

HappyMJ wrote: »

To me this is quite easy to compare. Do the timed method Monday-Friday when everyone is out then leave the heating on all day on Saturday and Sunday when everyone is home. Read the meter every morning at the same time such as when you leave home and you should have a good idea on how much more it costs to have it on all day and set to the same temperature.

You haven't taken into account the extra heat generated by the hot bodies of the people at home all day Saturday and Sunday.

malc_b

To answer grahamc2003

The 6kWh comes from the fact you've only saved 2kWh, not 8kWh. The house is still warmer inside than outside between 11pm and 7am. Hence there is still a flow of heat energy to the outside. That depends on the temperature difference. If we maintained 20C then it would be 1kW for 8 hours, so 8kWh. Assuming 10C at 7am and taking that as linear gives an average temperature of 15C so an average loss of 750W for 8hrs. So we have lost 6kWh to the outside. That has come from the fabric of house. When we turn the heating on in the morning we have to replace that 6kWh.

malc_b

UPDATED

wantanswers wrote: »

Now thats a good/practical post Malc, you might like to follow it up with a simple method/instruction of how to balance radiators..

You need a thermometer to start with. A DVM with a thermocouple can be got quite cheaply. You then need patience and a cold day. Run the heating with the themostat set max, all trvs set to max, and wait for the CH water temperature to get up to normal (ish) levels. Go round and record the temperature in, and out for all radiators and across the boiler. Ideally the all have a 12C difference (I think 18C or more for condensing, you'd have have check). Those radiators which are <12C need the lockshield shutting off, those >12C need it opening. However if the lockshield is near shut you'll see <12C diff but a much lower input water temperature than the other radiators so you'll know the flow is restricted to this radiator.

Of course shutting one lockshield will divert flow to other radiators so you need to take some measurement. Tweak some valves. Wait for it all to settle and measure it all again. I find it's a job you do over a few days. Taking a reading, tweaking then doing it again another day (otherwise the house gets too hot).

12C is the design figure for radiators so its when they give out their specified heat output. More drop is a lower average temperature so less output. Less drop is thus more heat output. But the bigger issue is that a lower drop means too much the water is flowing though just one radiator. You can't heat a house with radiator and you can't get rid of all the boiler heat with one radiator so the whole system performs very badly.

Updated 20C changed to 12C. I was in old money. It used to be 190F water in, 170F water out, 20F difference, 180F radiator average temperature. In C that is 12C diff, 88C in, 76C out. In round numbers 10C say. It doesn't have to be that precise. Larger drop is less radiator output but more efficiency from boiler.

malc_b

HappyMJ wrote: »

..if you turn the heating off even for a couple of hours then you will save money (not a huge amount but there are savings). The temperature won't drop much over a couple of hours and the timer can be set to come on a half hour before you come back home again so the house will be warm by the time you get home. The walls won't be cold and the fabric of the house won't cool down too much.

I'm sorry but that is too much of a generalisation. You don't save that much energy because unless the inside immediately reaches outside temperature when the heating is switched off (i.e. you live in a tent), then there is still an energy flow from inside to outside. You have to make up that energy.

Now if you have good heating control such a PID control like the CM67 I have then you will ramp up the house temperature without pushing the boiler. But if you have heating that just bangs on then you may well be running that in an efficient mode that negates the small saving of turning the heat off. For example a condensing gas boiler is 90% but a non condensing is 82%. So if turning off the heating means the boiler runs in non condensing it loses you 9% which probably outweighs the small saving.