The old winter chestnut

[oldie]

Hi All,
When I was a lot younger and Gas came from the local gas works, we were told that the most efficient way to maintain your house temperature was to set the room thermostat to your desired setting and leave it to control the heating and boiler, and to leave the timing setting on permanent.
Now many moons have passed and all sorts of "experts" have given their advice , on wether to time or not to time, to leave the heating on permanent or not.
So now every body is totally confused.Do we distroy the planet if we leave the heating on permanently to maintain a constant house temperature, or adversely is planet distruction caused by every body useing bucket loads of gas trying to get their houses up to a acceptable level twice a day.
What do you all advise and how have you controlled your central heating
A very confused
oldie

 

[Renewable M]

when you look at demand curves, the most fuel hungry bit is the warm up obviously. All that energy just to overwhelm the structural/fabric losses.

Look up weather compensation and you'll get some ideas. Nobody in germany would fit a boiler without weather compensation, but we're in the stone age.

Honeywell and siemens do all sorts of tick over controls for just this purpose.

 

[REDSAW]

surely it takes less energy to keep things warm than to heat things up from cold,
try it with your van and the heater, note how long the engine runs for from cold to warm up the cab against 1 minuite bursts.

 

[oldie]

Yes, thats what we were told, when I was still wearing short trousers, keep things constant ,so no massive temp changes during a 24 hour cycle. But things have now have supposedly changed,and the new"heat" is differant from the old heat it's much hotter.Sooooooooooooo
The second part of the question was, How do you set your heating. Sort of the reverse of the old maxin of "do as I say, not as I do" I'd like to do as you do, and not as some of the experts who have changed their minds more times than I've had hot dinners "claim" to advise.
oldie

 

[justlead1]

Hi A great question with to many variables to address. But i have an opinion. To analysis one needs a common denominator or datum, which would be hard to find with the differing characteristics of household properties in the UK. Even new builds where the qualification for fitting insulation is a tee shirt and tattoo's, are along way short of there potential. An earlier post mentioned Germany. The fitting of insulation there is far superior, inspected and snagged prior to covering up. Resulting in smaller capital costs and comfortable temps can be maintained through out the 24 hour cycle at an acceptable price to both the house owner an the planet.

 

[Renewable M]

at the moment, i've got my room stat set to 15 for tick over 24 hours. We knock it up when we're home.

I've lowered the boiler stat to very low.... and we're hardly using any fuel but the house is kept comfortable.

forgot to mention, my house is a victorian vicarage, so with the solid walls and draughty floor voids, it cools down very, very quickly. Once cold it takes an age to warm up. This method is working well for us, without having to keep the wood burners blazing while we're not at home.

 

[oldie]

Thanks guy's,
It looks ,as with all things, that the old advice, is the best advice, and one should ignor the words of the "born again experts"and stick with the words of the "Old un's". My old semi analog programer with it's levers, belts, pulleys and bits of string gave the option of continious running. But the latest "improved" digital version will only allow you to switch to the next timed setting , thats progress for you. Sooooooo it looks like a bit of giggery pokery with the timeing to achive a almost continious running time.
oldie

 

[Puddle]

As you say nothing has changed about the best basic operation of a heating system
What has changed is the quality of the insulated material we now use,which should mean less surround fabric to heat up on initial heat up and less to keep warm, once warmed up,thus less fuel keeping home warm
And also new controls that allow differant temps through the day are worth their weight in gold
Climatisers I have not really got into domestically but think that market will increase dramatically over next 5 years
After saying that,with this little snow burst,although it is nice to now see alot of houses with the snow staying on roof all day due to insulation,it is still surprising how many roofs are clear,snow melted and belting out lost heat,mind you I am in London,lots of rented property and Landlords not paying bills,so maybe some action requied there

 

[Deleted member 261]

I advise all my customer to keep the heating on 24 hours. I tried it myself a quite a few times and it does work. People still don't believe me but if you check your gas meter for a week and seek how much gas you use normally and then try it on 24 hours you should find a saving. You probably need to turn the thermostat on the boiler down and also it helps if the stat is in the correct location in the first place i.e. living room and assuming the windows aren’t open, Been checking on a few houses one of my neighbors has been doing running improvement first boiler (viessmann) then loft insulation, cavity insulation and double glassing he swears that the only real difference he notices was the cavity wall insulation but the bills have been coming down and down (in vol of gas used anyway). I would have thought loft insulation waold make the biggest change but
changing the boiler made the biggest difference then weather comp, then cavity wall then loft then double glassing.

 

[quality]

yeh compare heating your house to heating your van up in a morning proper good one that is not

 

[oldie]

Quality.
Strangly, I understand what the comparison is all about, starting a cold engine requires a terrific amount of fuel compared to one were the engine is already warm. So at least Redsaw34 has tried to give good advice that can be easly understood
Soooooooo how, what do you advise your customers to do, and more to the point, how do you heat your house, on timer or constant ?
oldie

 

[doitmyself]

Surely it all depends on what happens when you turn the heating off? In the "olden" days, when there was no insulation, double glazing etc, a house would quickly cool down overnight so the internal temperature next morning was almost the same as outside. So you effectively had to heat the house up from cold every day.

Nowadays it is completely different. Our house is now double glazed, loft and cavity insulated. The heating goes off at 11pm and, even when the outside temperature is below zero, the internal temperature only drops 3 degrees overnight (measured with a max-min thermometer).

Another point is that most people do not like sleeping in a warm bedroom. Keeping a bedroom at 21 during the day may be OK, but not at night.

 

[oldie]

Diy.
No, it's not about keeping everywhere in the house at a high temperature, most of my rads have stat valves fitted so rooms are set to what we feel is the most appropiate temperature for the use of that room.The question was really based on what is a more efficient way to use fuel, so in practice it dosen't matter whether a house is a modern fully insulated one or a old fashioned Victorian pile. It will still need a certain amount of fuel to reach a given temperature, now, is it a more efficiant use of fuel to keep the building at the chosen temperature constantly or to allow it to drop when not in use and then reheat. Obviously the better the insulation the less the differencal will be, but the question still remains a valid one.
Oldie

 

[doitmyself]

No, it's not about keeping everywhere in the house at a high temperature, most of my rads have stat valves fitted so rooms are set to what we feel is the most appropriate temperature for the use of that room.

I was not suggesting it was about keeping a house at a high temperature. I also have TRVs on all the rads which are set to the required temperature

The question was really based on what is a more efficient way to use fuel, so in practice it doesn't matter whether a house is a modern fully insulated one or a old fashioned Victorian pile. It will still need a certain amount of fuel to reach a given temperature, now, is it a more efficient use of fuel to keep the building at the chosen temperature constantly or to allow it to drop when not in use and then reheat. Obviously the better the insulation the less the differential will be, but the question still remains a valid one.

But it's not just about the efficient way of using fuel. If it was, then you would never heat your house as that uses no fuel at all. It's about maintaining the required comfort level as economically as possible.

To take two examples at the opposite end of the spectrum.

First: an uninsulated house which looses all its heat instantly, i.e it rises from 10C to 20C instantly and drops from 20C to 10C instantly and you have the heating on for 16 hours a day. So it runs for 16 hours at 20C and 8 hours as 10C. The average temperature is ((16x20)+(8x10))/24 =16.7C, i.e 3.3 degrees below daytime temperature. Assuming each degree drop saves 5%, you will save 5 x 3.3= 16.5% compared to heating the house continuously.

Second: a very well insulated house which looses and gains heat at a rate of 0.1 degrees per hour. So it will cool down for 4 hours to 19.6C and the heat up for the next 4 hours to 20C. The average drop overnight will be 0.2C. So the average temperature is ((16x20)+(8x19.8))/24= 19.9C, a reduction of 0.1C. So the saving will be 5x0.1 = 0.5%

So, the better your house is insulated, the less fuel you will save by turning the heating off. But who will be more inclined to leave their heating on 24 hours a day? The person who lives in the badly insulated house of course!

 

[Deleted member 2053]

Heat loss is dependent on temperature difference so the mathematical answer has to be that that it is cheaper to turn the thing off. However, I think there must be other variables here like when your hands are so cold that it you cannot feel the timer buttons to turn the heating back on then you tend to overheat the place because you think you are about to die from hypothermia. So the reality is that folks probably tend to run the heating at a lower temperature overall if they are kept warm 24/7 and the overall result is a saving.

 

[oldie]

Do it Myself
I had assumed that everybody would accept that it is inefficiant to heat a large space such as a house and that the most efficiant way to consume fuel would be to heat the individual,but times,thankfully have changed and it is now generally accepted that we do not go round wearing wooly mamoth skins to keep warm, most of us would like to maintain a comfortable if not a shirt sleeve enviroment, around the house, and this is what my original question was all about. I except that all houses are not the same and like wise the standard of insulation in those houses . Unlike my friends in Canada that have as standard triple glazeng and 12" of sheepswool between the skins of their outside walls. We have to start with the majority of housing stock in this country that will never be able to enjoy a resonable amount of insulation. So the original question still remains a valid one that is, is it a more efficient use of fuel to continually heat a building, regardless of it's insulation ,or to use a timing device to control the heating to end up with a comfortable living enviroment. Mathmatics unfortunately do not take into consideration the vagarious of people who are not actually intersted in formula but what the next gas bill will be and can they afford to heat their propertys.
oldie

 

[doitmyself]

people who are not actually interested in formula but what the next gas bill will be and can they afford to heat their propertys.
oldie

Then it's a matter of deciding what your priorities are: a warm house or a holiday in the Seychelles or a new BMW Z5, etc.

My dad, long gone now, would frequently comment that people only considered the cost of buying a house, they never gave any thought to the cost of running and maintaining it.

 

[Renewable M]

the new home information packs will nail that one doit. Energy rating. Brilliant. Should create lots of work for installers.

I dont follow your model of a well insulated house gaining/losing at a given rate. There are lots of variables in that one. o.1 deg /hr is a mighty slow warm up, unless you are using a candle.

Burn wood and get warm twice..... once when you chop it and once when you burn it......

Anyway, the very well insulated structure will require less heat energy/time to achieve a required temp. Then, because of the superior fabric will retain more heat for a longer period of time.

The house with double the insulation will save an arm and a leg. You can do a basic calc on your own living room. Take the actual U values and then imagine you have 200mm of closed cell insulation in the walls.

Compare the energy cost of warming that space, and work out the temp drop over a given time period (for arguments sake 4 degrees, which is commonly the hysteresis of a mechanical room stat and the duration between room up to temp, and boiler re-starting)

I know it's schoolboy stuff, but the differences are staggering when you extrapolate over a model for seasonal use.

Dammit, need a beer. Night all.

 

[oldie]

Christ, Renewable,
You need a beer, after reading this I need several beers : ) , if only most of the housing stock in the UK could reasonably fit 200 mm of insulation the world would be a better place, but most of us rely on someone,as described earlier in the thread as tee shirt and tat's qualified to comply with the latest reg's and their installation is very rarely checked, I doubt if most housing stock has anything like that amount of insulation or if ever is likely to achieve any thing like this amount. Soooooooooooo forgetting the axe and log's,I'm now too old for that game "oldie is the clue" I now get mine already split to size,the question is still, Timed or Continuous : )
oldie

 

[doitmyself]

I dont follow your model of a well insulated house gaining/losing at a given rate. There are lots of variables in that one. o.1 deg /hr is a mighty slow warm up, unless you are using a candle.

I agree that it was possibly an over-simplification; but who wants to get involved in detailed calculations using Newton's Law of Cooling etc? They were extreme examples.

 

[Renewable M]

We've had our heating 'on' for 2 weeks now, non stop. House is comfortable, and our gas consumption is down on last year, when we just had it on for timed periods.

I am going out to collect another 20 rolls of the recycled plastic bottles made into loft insulation this afternoon though. That should have a positive influence.

 

[quality]

Do it Myself
I had assumed that everybody would accept that it is inefficiant to heat a large space such as a house and that the most efficiant way to consume fuel would be to heat the individual
oldie

That was my point but I`m not to good with words

 

[oldie]

Quality,
No problems my friend,
My quote was not aimed at yourself but at A n Other, As for not being good with words, they are only a means of communication between people and if you can make other people understand what you are saying ,then your words are as good as anybody elses. Me i'm Dyslectic and I can't spell for the life of me ,soooooo I spend more time with my portable spell checker than most people would take to write their life stories. That being said is your heating set to Timed or Continuous : )
oldie

 

[quality]

Yeh I am a full time maintained continuous type

 

[oldie]

It's about time to Say,
Thanks for all of your advice and so freely given, it's a great forum with brilliant people as members although I have noticed people arrive throw in a question then leave without so much as a thank you, your help is very much appreciated by most people even if they don't say so
Seasonal greetings to all and I hope that the New Year brings with it a much better time for all.
oldie