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

147718

Should we apply simple logic to our heating
If you are cold turn it up
If you are hot turn it off
If it is on its costing money
If it doubt do nowt

malc_b

bestyman wrote: »

I`m having trouble keeping up at the back.

Summary:

Some people report report that running 24/7 uses less fuel. I've reported that some uni notes I have say per day, overnight off could be as much as 95% of 24hr consumption and then explained why this is so with a model and some maths giving an 8% night saving (dropping to 4% if insulation is doubled).

I've then pointed out that at this low level of difference it is the same range (or less) than the difference between condensing and non condensing. Hence it is entirely possible that the reports of savings on 24/7 are true.

I should say that the optimum fix rather then 24/7 running is probably better controls as you do lose less heat from the house for short running.

wantanswers

bestyman wrote: »

I`m having trouble keeping up at the back.

I'm ready with me bag of coal Besty! (post 225)

macman

147718 wrote: »

Should we apply simple logic to our heating
If you are cold turn it up
If you are hot turn it off
If it is on its costing money
If it doubt do nowt

352 posts in and someone has finally got to the nub of it-thanks. Nothing more to be said really.

Troublemaker66

Cardew wrote: »

Well your FIL is completely wrong!

You say that you leave heating set at 20 when away for the weekend.

If you were away for two years, would you leave it set to 20C?
How about a month? A week? At what point do you feel the laws of physics don't apply?

Here we are up against the cause and effect lobby versus the solid state lot. By which I mean that the C & E lot think that heating only works when you use energy to heat from cold, and the SS lot say keep it on full belt and it only goes down a bit. Both probably a bit wrong.

Ideally, heat from tepid is best as it uses half the energy but still doesn't waste it as much as keeping it going all the time. When I go away for a week, say, I turn the heating down to auto, which comes on twice a day, just the radiators, not the hot water, which heats by solar power. When I turned it off, it took two solid days to warm the house up again, and I was shivering for that time.

I have radiator thermostats as well as a thermostat on the boiler, but I can't work out which point has them full on or full off. I haven't been able to experiment sensibly. My system is inefficient, because the boiler isn't 'modern', but it works, my loft is fully insulated, and I keep all doors closed. Latent heat shouldn't be ignored, nor should a level of heat that keeps the walls not in contact with the outside, warm.

I have a fully insulated hot water tank, so if I need hot water for anything, (hardly ever, as I use an instantaneous shower) I can turn it on on purpose. The solar panels are pretty useful, but I don't generate electricity for export so much as for free use in the house. I do the major stuff when the daylight is strong (it still generates when it's cloudy but light).

So no, don't leave the heating on full belt, but have it on and let it boost to half at least, so that it doesn't have to be on full belt when you come back, but doesn't waste heat you aren't using. Remember that a slightly warm house is less likely to have burst pipes.

HappyMJ

Troublemaker66 wrote: »

When I turned it off, it took two solid days to warm the house up again, and I was shivering for that time.
.

Come on...2 solid days. It takes my house less than an hour with the boiler on it's maximum setting to heat from freezing cold if I leave the heating off for days at a time. If my boiler was on maximum for 2 solid days 48 hours then the gas consumed over the month would double. I'd use 700kWh just over those 48 hours. I use less than 700kWh in a month and my heating goes off during the day every weekday and down to low at night and if I go away for a weekend I turn it off and return to a cold house after the weekend....but less an hour later it's toasty and warm.

Cardew

Troublemaker66 wrote: »

Here we are up against the cause and effect lobby versus the solid state lot. By which I mean that the C & E lot think that heating only works when you use energy to heat from cold, and the SS lot say keep it on full belt and it only goes down a bit. Both probably a bit wrong.

Ideally, heat from tepid is best as it uses half the energy but still doesn't waste it as much as keeping it going all the time. When I go away for a week, say, I turn the heating down to auto, which comes on twice a day, just the radiators, not the hot water, which heats by solar power. When I turned it off, it took two solid days to warm the house up again, and I was shivering for that time.

I have radiator thermostats as well as a thermostat on the boiler, but I can't work out which point has them full on or full off. I haven't been able to experiment sensibly. My system is inefficient, because the boiler isn't 'modern', but it works, my loft is fully insulated, and I keep all doors closed. Latent heat shouldn't be ignored, nor should a level of heat that keeps the walls not in contact with the outside, warm.

I have a fully insulated hot water tank, so if I need hot water for anything, (hardly ever, as I use an instantaneous shower) I can turn it on on purpose. The solar panels are pretty useful, but I don't generate electricity for export so much as for free use in the house. I do the major stuff when the daylight is strong (it still generates when it's cloudy but light).

So no, don't leave the heating on full belt, but have it on and let it boost to half at least, so that it doesn't have to be on full belt when you come back, but doesn't waste heat you aren't using. Remember that a slightly warm house is less likely to have burst pipes.

The question asks which is cheaper!

Every time this subject is raised(and it comes up several times a year) the question posed is ignored and we have - like your post - a compromise solution between comfort and cost.

Given the situation in every property is different, it is not possible to quantify just how much extra it costs to have the heating set as you advocate, but one thing is absolutely certain; it will cost more than having it switched off all the time until you need heat.

Martin has just published an update on this subject:

http://www.moneysavingexpert.com/utilities/energy-saving-myths

Q. Should I leave the heating on low all day, or turn the
thermostat up and down?


a. You'll save energy, and therefore money, by only having the
heating on when it's required. Using a timer is best, because your thermostat is designed to turn your heating system on and off to keep your home at the temperature you set it.


MSE forum feedback: Some complain this tactic risks you being cold, because it can take time to heat up homes, especially larger onees.


Of course, that may be true, but this is a MoneySaving
site, so we’re focused on cost. The EST’s advice (backed up by British Gas) will save you money.

Yet as a balance, if you’re worried, switch the timer on a little bit earlier, so the house will be nice and toasty
when needed, but you’re not pumping out energy all day.

malc_b

IMO Martin's FAQ should say

"Yet as a balance, if you’re worried, switch the timer on a little bit earlier" - or better still consider changing the thermostat to a clever controller which will turn on the heating just earlier enough to get the house warm for you.

That's the optimum between comfort and savings.

On the subject of going away and then the house taking days to warm up I can remember when I had coal fired heated (which has to be fully switched off) coming back to the house after going away at xmas and it taking 2 days before the house felt normal and warm again. The weather was very cold then so the house had also got very cold.

It's also something that depends on the house construction. Brick, block, plaster as in old houses is going to soak up a lot more heat than celcons, or brick clad timber framed houses.

I suspect as someone else has posted if you get condensation in the cavity and brickwork then it can take a long while to dry out that water so again this would be more an issue when it is very cold. And unless you are going to turn the water off it makes sense to leave the heating set just very low (10?) to prevent pipes freezing.

wantanswers

HappyMJ wrote: »

I'd use 700kWh just over those 48 hours.

Complete Rubbish...in my opinion!:rotfl::rotfl:

wantanswers

If you are away for any length of time during the winter check the long range weather forecast and if it appears reasonable turn it off 'and' the water......leaks cause devastation.....believe me.