Probably stupid question about this keeping the heating on constantly at 16 degrees thing

[virgiltracey]

how do I do this if I don't have a thermostat? We have thermostatic valves on the radiators but no room thermostats? Will I still get the same benefits/savings if I have the heating on constantly but the radiators all on low or not? I'm a bit confused since presumably a room thermostat turns the boiler on and off whereas presumably a radiator thermostat just lets more hot water in (but its constantly being heated)???!! .

We MUST get our oil bills down this year and so any other heat/money saving tips gratefully received!

Has your boiler got settings? I have no thermostat but 11 settings on the boiler with 1 being barely on at all and 11 full whack. I've got it on a constant 2 at the moment and last year on the coldest days kept it on a constant 9

Foil reflectors behind the rads can help also.

hmm not sure lubey. I will send DH to have a look when he gets in!

I am very late on this, but if you have no room stat, you really ought to get one. If you are competent to DIY it will cost less than £20 including cable and pay for itself in economy in a month or so. It will also improve comfort. If you have to pay someone else it might cost half a day's charges at most. You need a timer as well, I hope you have got one. You can buy room stats which incorporate their own timer, but they are quite a bit more expensive.

tell me more of this 16 degrees please. what about when it is really really cold? would i be allowed to crank it up then?

some people think it is cheaper to heat the house constantly than to heat it only when you are at home and not in bed. This is actually not true, since

heat loss is proportional to (temperature difference) x (time)

However 16C is a modest temperature, rather cool but OK if you are wearing a jumper and thick socks, but a lot of the time (assuming you have a room stat set to 16C) the boiler will not actually come on much. Down here today, outdoor temperature has been 14C and indoor temp (sun coming in through windows) has been 18C. I live in the sunny south.

We can't do the thermostat thing - too much difference between the rooms. What we do is have the timer constantly coming on and off - I think the segments are about 15 mins each so 15 mins on and 15 off all the way through - and the setting on the boiler between 4 and 6 (max 10). In the coldest part of winter we just have 3 hours off in the middle of the night, and 6 hours during the day (while at work/school etc) and this seems to work without being horrendously expensive. HTH.

Oh, and we tell DS to put a jumper on if he's too cold, and I keep a large collection of shawls etc for us and visitors. And a woodburner if we can be bothered...

PerAr6ua
"We can't do the thermostat thing - too much difference between the rooms."

You can adjust relative the heat output of radiators by balancing them, using the lockshield valve. This reduces the output of the rads in the hottest rooms, relative to the rads in the coldest rooms.

I can explain if you want.

Totally agree with you PigletJohn.

16 must be too cold surely for real comfort.I thought 21 was about right for a living room and 18 for a bedroom.I'm not hot if its 24 .
(We have a very small place though so it's not too bad to keep it cosy,and we supplement with an open fire)

Piglet - we do balance the rads - upstairs they're between 1-3 depending on the weather, down in the cellar (also living accommodation) they're always at 6.

We've got a half-subterranean flat in a 300yo house where the upstairs bedrooms get tons of sun, so the temperature differences really are extreme!

On the plus side my kitchen never gets too hot unless we've got people for dinner and I forgot to turn the rad off, so I lived in there when the temp hit 30 this summer and had to put socks on against the cold floor

so tell me more about "We can't do the thermostat thing - too much difference between the rooms."

the thermostat is intended to turn off the heating once the coldest room (or the slowest one to heat up) has reached its target temperature.

If, as I gather, your rads have TRVs on them (this is not the same as balancing) then they will prevent the hottest rooms from getting too hot.

So I don't understand yet why you can't use a room stat to turn off the boiler once all the rooms have reached their target temperature.

Can you help me here?

Oh, right, well there's no heat control on the rads - just a valve marked 0 to 6. So if the cellar was toasty warm then chances are the bedrooms would be sweltering, unless we kept a close eye on the temp and possibly turned the rads off upstairs altogether...

Oh but seriously Piglet - how much does my rubbish heating system matter to you?

If it doesn't matter to you, not at all.

mine's on at 17 (in rented flat and there isn't a timer or thermostats in any of the rooms). It has only come on once - in the middle of last night, which made us all too hot and woke ds2 up (although it doesn't take much). my last house had a timer, and we had huge bills, so it will be interesting to see what the bills are like this winter. I might turn it down to 16 though.

I remember when mine were babies and the recommended temp was 18 - that always seemed too cold for me.

PigletJohn tell me more about this. I was in 2 minds but a CH engineer told me recently that it WAS worth keeping it on low 15-16 deg 24/7 in the winter (not yet obviously as it's damp but not freezing)

His theory was it takes more energy to heat the house up from below freezing every day than to keep it ticking over (at whatever you choose) & then boost as needed for early mornings/early evenings.

I'm managing to leave mine off most of the day but it's set to come on for 2 hours am/pm if it drops below 15. I'm saving myself for when this predicted Arctic Winter starts....deep joy!

i have mine at 16 and it is too warm. i can't leave it on at 16 constantly. i just switch it on when i feel cold and swithc it off when i feel warm. maybe i should have it on at 15 constant?

Bossybritches22

it is a common myth but it is untrue. keeping your house warm all day will make it more comfortable, but it will use more energy than turning it off when unoccupied, and letting the timer start it up again so it will be warm by the time you get back.

All building materials (walls, ceilings, windows) have a rate at which they will lose heat. Wikipedia says "The U-value (or U-factor), more correctly called the overall heat transfer coefficient, describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The usual standard is at a temperature gradient of 24 °C, at 50% humidity with no wind (a smaller U-value is better)"

The "U Value" is the number of watts, per square metre, lost.

The amount of heat you lose (slightly simplified) is

U value x the area in square metres x the temperature difference

So if you double the number of square metres (e.g. the wall is twice as big) you lose twice as much heat.

If you double the temperature difference (e.g. instead of the inside being at 15 degrees and the outisde being at 10 degrees, giving a temperature difference of 5 degrees, you decide to heat the inside to 20 degrees, giving a temperature difference of 10 degrees), you lose twice as much heat. If the temperature difference is nil (e.g. the outside temperature and the inside temperature are both 10 degrees) you lose no heat.

The amount of energy you use is the heat loss x time.

So if you are heating your house to the higher temperature for ten hours, you will use twice as many kWh as if you heat it to the lower temperature for ten hours. If is the same temperature as outside you will use no energy.

However it is true that if you have been away on holiday, and the house has cooled to 15 degrees, it will take a certain amount of time to come back to 20 degrees, and the house will be less comfortable until the entire fabric has reached this temperature.

Houses with low U values (e.g. with good insulation of walls and loft) will lose less heat and will cool more slowly, but that it a different question

Thank you PJ!

So my parsimonious ways are not as dotty as feared, marvellous!!

Sorry guys I'm still confused. We have oil heating. Boiler is in the garage. Its a dual circuit system (???!!) so downstairs can be on and upsatirs off (or vice versa). The radiators have valves on them going from 0-5 so we can turn them up or down but there is no room thermostat. Can we also have a room thermostat? How would that work?

And did we get to the bottom of the heating on low thing since I also thought that its better to have the heating on constantly but low than to let the house get freezing cold since it apparently heats the fabric of the house.

I am very confused!!

yes you can (and should) have a room stat. If you are having to get a new one, you might consider getting a programmable one that can be set to different temperatures for different times of day.

As you have two circuits you ought to have an upstairs stat and a downstairs one.

The room where the wall stat is should have the thermostatic head removed, or turned up to max which must be higher than the room stat, otherwise it will turn off the rad in that room, and the boiler will constantly keep trying to make the house warmer to satisy the room stat. The rad in the room with the stat should be balanced* so it warms up slower than all the other rooms.

Yes we did, no it isn't. See above.

*that is a different topic.

whether or not keeping the house constant will save energy vs. putting the heating on when you need it depends entirely on how much you're in the house - we're out all day every weekday and don't need heating at night (even in depths of winter) - keeping the house at 16deg all day and night would definitely cost us more than heating it up to 19deg from 6pm to 10pm and 7am to 8am only.