Heating on low and constant better?

Cardew

mech wrote: »

[/size][/font] He did?

IMO Yes; but I accept you don't understand why.


[/size][/font] Oops. My apologies. Indeed, they were posted by albertross. I lost track of which person I was responding to.

Accepted.


Well you have a point there.[/size][/font] I have to concede that you're probably right. But I contend that the statement is ambiguous. It could mean either in the context of this thread. Especially when submitted as evidence. It seems to me that albertross made the same interpretation as I did, or the link would have to have been irrelevant.

Probably right? ambiguous? How so?

albertross can speak for himself, but I wouldn't agree with your assumption on his interpretation.
It seems to me that if up to £16 can be saved merely by switching off before going out and 30 minutes before going to bed, it amply demonstrates that much more than that can be saved by having it off all night and all the time you are out.

If it was meant to be that vague they couldn't have put a yearly figure on it could they? The assumption is that they mean every day.
[/size][/font]

Again you have not understood. You have accepted that I was "probably right" so you have conceded that you(probably!) did not read the BG statement correctly. Therefore the question posed does not need an answer

Slightly, but what I misunderstood was ambiguous. Your misunderstanding was simply from not reading what was written.

Pray tell me what I have misunderstood.

BexTech

C ?

tomstickland

It's house B. The only way "on all the time" could somehow save energy is if there's some complicated interaction based on boiler efficiency for different operating circumstances.

BexTech

I answered C for the question: "Which house loses the most heat through the walls/windows/roof,".

The other question " Which house(s) lose the least heat through the walls/windows/roof" wasn't there when I posted, nor was House E.

There was only 1 question and 4 house when I posted.

Cardew

House C loses the most heat, as the temperature differential(between inside/outside) is greater for for the longest time and the law of thermodynamics states etc etc. This house will have the highest bills.

Houses B & E will equally lose the least heat.
This is on the assumption that the 8 hours 'on' in house B is in one single period of time as in house E. The temperature differential will be the same for both houses.

If the 8 hours heat on in House B is in shorter periods(e.g 2 periods of 4 hours), then E will have the least loss.

djohn2002uk

" House C. Outside temp is 0 deg C, inside is 24 deg C, 24/7."
This is my answer because albertross failed to let the rest of you in on the facts that it has no cavity wall insulation and no loft insulation and they like having the windows open at night.:p

mech_2

All other things being equal, House C theoretically loses the most heat, but it doesn't necessarily follow that it costs measurably more to heat than house D. It depends on the house. If house D is reasonably well insulated and the owner has an old fridge, they'll probably notice more of a saving on their electricity bill than their gas bill.

House B loses the least heat, almost neck and neck with E by as little as makes no difference unless the owner has their windows open all winter. Followed by A (by a narrower margin than than between C and D).

The only significant difference in all cases is between the 20 degrees examples versus the 24 degrees examples. When you factor in the type of boiler, thermal mass of the building, solar gain, insulation, flue loss etc and put in some numbers, maybe we'll have a clearer picture.

What is an "average" house anyway? Modern houses (the past 20 years?) are much better insulated than a retrofitted 1930s semi like mine, but they also have a much lower thermal mass. The inner skin of the exterior walls would be lightweight blocks and non-load-bearing walls would be partitions, not brick and block respectively as in my house. If you average out the insulation and thermal mass of the two houses, you end up with a house that is less well insulated than the modern house, but with a lower thermal mass than the older house. A house that stores less heat than the old house, but loses it more quickly than the new house. So you end up with a better case than either type of house for turning the heating down at night/when out. The problem is the house isn't real and the numbers can't be verified by anything that is real.

Ultimately you have to come up with a good reason why each householder shouldn't just suck it and see.

If TITEASCRAMP wants to reduce her heating bill, messing about with the timer or TRVs is a waste of time. She should have a roomstat fitted somewhere central (eg hallway) and turn all the TRVs to maximum. Then turn down the heat on the boiler itself until it switches off at no more than 70 degrees C (assuming there's a temperature gauge on the boiler as on mine). Only turn any TRVs back down if a small room then gets unbearably hot. If her meter readings are correct, she's using more than twice as much gas as I use to heat my non-doubleglazed 3 bed semi to a similar temperature. Her heat loss is in the flue, not in the walls/roof/windows/floor.:beer:

mech_2

albertross wrote: »

see post 115

I saw it. It didn't address the issues I raised.

TRVs are designed to minimise waste, if they are fitted, you may as well use them properly by setting them to a comfortable maximum level.

They are bad news without a roomstat. Especially with a condensing boiler. When the house gets warm enough they all turn off and the boiler is still on, cycling, pumping heat out through the flue because it bypassed all the radiators and has nowhere else to go. The boiler will then spend a lot of its time in non-condensing mode as the return water will spend a lot of its time at a high temperature. Why keep burning gas when the house is warm enough? TRVs don't turn the boiler off!

TITEASCRAMP's readings are metric.

Yes I know she said that. So are mine. Maybe hers are imperial after all?

TITEASCRAMP

Yes my bills are £28 DD and do cover usage.
I have tried turning it off at night like sugested and the usage has gone down by .6 of a unit. per day.
Just to add I assumed mine were metric because the meter was only installed about 6 months ago.
I live in a 80 yr old property.

WestonDave

Part of the problem is surely the difference between controlled scientific experiment and what happens in a real house with real people once many of the control present in the experiment are removed.

Of course in an imperfectly insulated house, with a reasonable temperature gradient between inside and out, it will cost more to keep that house at 18C 24/7 than to heat it to that level for 2+1 hours a day all else being equal.

However here lies the rub. Firstly we aren't measuring in tiny units of measurement. £1 is roughly 4 or 5 Kwh of electricity - that's at least 240,000 Watts difference to make even a slightly statistically significant difference in bills. By the time they've messed with the charge rates since last year as well that means you've got to see fairly massive differences to stick another £10 on a quarterly bill.

Secondly if Titeascramp's house is anything like mine, its pretty much maintaining its own heat at present due to the relatively mild conditions outside. Although my heating is on 24/7 set at 17C during the day and 14C at night (in reality its probably only drifting to about 15 at worst), the only time it actually fires, is for about half an hour in the morning to overcome the down drift overnight. So my system is mimicking one which is timed for a couple of hours in the morning. That is due to the house having double glazing, loft and wall insulation plus 2 adults and 2 kids using other heat sources in the house as well as generating their own body heat.

Finally I'm willing to bet that if you took two real life scenarios, you would not find one heating to 18C 24/7 and the other heating to 18C for 3 hours a day because quite simply in the latter case the loss between heats would make the house uncomfortable if 18C is the minimum comfortable temperature. It is therefore more likely that in the second scenario the house is heated higher - say 22C in order to allow for the loss during the day. That house will be less comfortable to be in - too hot at some points and too cold (amplified by the overheating earlier!) at others.

I guess in short my point is that in real life, too many of the controls and assumptions which are used to make good scientific theories don't hold true which seriously undermines the practical application of the science.

Cardew is right in the pure sense but I can see how Titeascramp is seeing what he is seeing because in monetary terms its so hard to see a real difference.