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

wantanswers

Cardew wrote: »

It may be of interest but what is the relevance?

The relevance for me is that by keeping my heating on 24 Hours in this very cold weather it appears to be saving me money. Although until I compare it with other operations it may not.

Also to be fair and because you have asked, I perform a little extra in there, but i need more data before i am satisfied it is contributing to my saving!

Cardew

wantanswers wrote: »

The relevance for me is that by keeping my heating on 24 Hours in this very cold weather it appears to be saving me money. Although until I compare it with other operations it may not.

Also to be fair and because you have asked, I perform a little extra in there, but i need more data before i am satisfied it is contributing to my saving!

'Saving you money'? measured against what criteria?

By turning down the heating to 17C for 11 hours you are effectively turning off the heating for an (unknown) period until the temperature of the room where the thermostat is located drops to 17C. Depending on a lot of (unknown) factors that period when the boiler was 'off' could be less than an hour, or it could have remained off for the whole 11 hours.

The only certainty is that turning it down to 17C will save you money against the situation where you left it set to 20C for those 11 hours.

I have my heating, set at 20C and timed so that it goes off at, say, 10pm and comes back on at, say, 7am.

I could achieve the same effect by leaving the heating on 24/7 and turning down the thermostat to, say, 10C at 10pm. The house would never drop to 10C and so the heating would never come on until I turned up the thermostat back up to 20C at 7 am.

So using the(silly) criteria used by some people I could claim to have left my heating on 24/7.

steve-L

macman wrote: »

Not to worry Cardew, I'm hanging on.
A shame though that we can't capture all the hot air being generated by the 1st Law of Thermodynamics deniers: if we could, no one would be cold this winter.

Because its really not that simple.....

The cheapest case is not to use ANY heating.....
At the other end is keeping the house heated at 28 or 30 degrees... (Remember the case of the Nigerian Ambassador who had a team think he was growing weed due to the excessive heat signature of his house?)

Depending where your own comfort levels are as well as if you are in a terrace with people heating either side or flat with people heating below you will make this a 'suck and see'.

If you leave the heating at 15 degrees all day or not.....or leave it on at 21....

How much heat is lost into walls when pipes go through them and then cool... are all somewhat imponderable not to mention if you have a boiler for hot water but also an electric on demand shower........

Me personally I can't stand leaving a shower for a cold bathroom... (probably spending most of my adult life in tropical and semi tropical environments) but it doesn't bother my mum at all.

Some places I lived the bathroom heating was through towel rails with no real thermostat ... other places radiators.. some places the bathroom is on 2 or even 3 external walls... other places mainly internal...

Some people might be happy going around and turning individual radiators on/off through the day by hand.... and leave only one on... others might turn the heating off all together and heat a living room which they have insulated better with electric....

My brother has a ultra sophisticated central heating where he can set each room seperately by both temp and time and even change it from his mobile phone.... he also has a huge heat storage device (swimming pool)...
His heating is always on, just down low.... so he might have 12 degrees upstairs until a certain time and then start heating it...

What sounds like a no brainer from a pure 1st law of thermodynamics POV is quickly lost in the different comfort levels, insulation levels and sources of alternate FREE heating like neighbours.

And in the end, letting your pipes freeze is poor economy!
My mum did this a couple of winters ago!

wantanswers

measured against what criteria?

Against my criteria, because I am interested in saving my money, well now i am. But as I said I need more data from what I am doing to convince myself I am saving money.



The only certainty is that turning it down to 17C will save you money against the situation where you left it set to 20C for those 11 hours.

I am in total agreement with that, with the exception that from the early hours of the morning I have maintained my house (certain parts) at 17C at a cost of course which I know!

BTW 17 is just a figure I have plucked!



I could achieve the same effect by leaving the heating on 24/7 and turning down the thermostat to, say, 10C at 10pm. The house would never drop to 10C and so the heating would never come on until I turned up the thermostat back up to 20C at 7 am.

Totally agree.

Anyway i'll persevere with some more trials whilst the weather is very cold...its probably the best place to start.

wantanswers

Cardew wrote: »

I have my heating, set at 20C and timed so that it goes off at, say, 10pm and comes back on at, say, 7am..

May I ask you a question please just out of interest.

You say your heating comes on at (say) 7am. Do you know how long it takes for you to raise the temperature of your house to 20C and what units of gas you use during this time?

Should add during this cold spell of zero day and night temperatures.

oldskoo1

Cardew wrote: »

I have my heating, set at 20C and timed so that it goes off at, say, 10pm and comes back on at, say, 7am.

I could achieve the same effect by leaving the heating on 24/7 and turning down the thermostat to, say, 10C at 10pm. The house would never drop to 10C and so the heating would never come on until I turned up the thermostat back up to 20C at 7 am.

So using the(silly) criteria used by some people I could claim to have left my heating on 24/7.

Would there be a cross over point in gas usage?

So i'm thinking, your 10c would never get the boiler working overnight, at least now. My stat is in the hall so 16.5c = 21c sitting room, 19c bedroom.

Overnight its set to 12c. This never activates in this weather. Overnight the stat will fall to 14c, lowest 13.5c (at the moment).

In fact the rate of heat loss falls off so dramatically in my house that no heating for 24 hours still produces around 13c on the stat.

So i'm pondering, is there a cross over in gas usage, i've never tested it, there must be, but at what point?

If my house settles around 14c overnight (at current temperatures). What if i set it half a degree higher, or maybe at 15c overnight. I anticipate it would take 3 or 4 hours to fall to this temp. Then the boiler will kick in around 2 or 3am. I will still loose heat but will i reach a cross over point where the gas i use to maintain a lower heat will equal the gas used at say 10am once the house has warmed up again but from a colder starting temp?

E.g.

1) 13.5c to 16.5c
v
2) 15c to 16.5c (but gas used overnight to keep a 15c floor). I'm thinking if my heat loss dramatically falls off around 14c there might be a cross over point?

laptop80

wantanswers wrote: »

May I ask you a question please just out of interest.

You say your heating comes on at (say) 7am. Do you know how long it takes for you to raise the temperature of your house to 20C and what units of gas you use during this time?

I think I know this one. Is it (a) Less than would be used to heat the house to 20C for 24hrs/day?

Am I right Cardew? I know I don't know the thermal mass of your house, your favourite colour or whether you prefer baths or showers, but I just have a feeling about this one.

wantanswers

On a different subject Laptop 80 re routers.

Just read your interesting post about line speeds. I'm one who switches off at night, not because of saving but just because of habit. Will start and leave it on now!

Cheers.

laptop80

wantanswers wrote: »

On a different subject Laptop 80 re routers.

Just read your interesting post about line speeds. I'm one who switches off at night, not because of saving but just because of habit. Will start and leave it on now!

Cheers.

I used to switch off partly to save electricity and partly because my first router burnt itself out and probably would've caught fire if I hadn't been there to switch it off.

wantanswers

laptop80 wrote: »

I used to switch off partly to save electricity and partly because my first router burnt itself out and probably would've caught fire if I hadn't been there to switch it off.

Cheers...on second thoughts I'll switch off...Bu£$er the line speed.