Heating - cheaper on all the time or when needed ?

[mikeyw]

Just wondering what the consencus is on heating - is it cheaper to leave on all the time with the boiler heating the house as needed or to switch off completely and use only when needed ?

House is a 30yr old 4 bed detached

Tia,
Mjw

 

[dhutch]

Just wondering what the consencus is on heating - is it cheaper to leave on all the time with the boiler heating the house as needed or to switch off completely and use only when needed ?

House is a 30yr old 4 bed detached

Tia,
Mjw

Popcorn time!

 

[joe-90]

Well the physics are quite simple. The more heat you put into a house then more heat will escape from the house. That's why you heat your kettle when you need it.

 

[Gywndy]

At the risk of sticking my head in to the lion's mouth .............. this debate has been raging for years and is one which seems to raise contributors' temperature to boiling point! Do a search on Google and you will find links to various forums where the topic has been hotly debated.

A builder who writes a column in the Telegraph is a strong supporter of constant temperature heating and published another letter and comment about this in March 2012 - http://www.telegraph.co.uk/property...08/On-the-level-Jeff-Howells-home-advice.html (second article). I e-mailed him and pointed out that his correspondent's energy usage would have been substantially reduced anyway during the last winter quarter because of the mild conditions and that he would have probably saved even more if he had used proper controls. That argument was summarily dismissed!!

If you look at my recent post about what I perceived to be a problem with my Honeywell CM927 wireless thermostat (//www.diynot.com/forums/plumbing/honeywell-cm927-holiday-mode-problem.346392/) you will see that by setting a constant control temperature for 2 weeks I actually used considerably more gas than would have been consumed using a normal heating program. I now believe that there is not an issue with the CM927; the 'problem' is with constant temperature heating, in my case at too high a set point.

My own preference, based on many years of managing not only my own domestic heating but also a large industrial installation, is to use accurate temperature control and cycle the temperature up / down according to occupancy times, comfort level required, etc. My central heating is never 'off' but the temperature set points change at defined times. I certainly wouldn't like to try sleeping in an overheated bedroom!

My advice to you is to do your own experiments but for validity of results try and choose periods when the ambient conditions are similar.

 

[Agile]

Well the physics are quite simple. The more heat you put into a house then more heat will escape from the house. That's why you heat your kettle when you need it.

Joe is quite right even though he is not a heating engineer.

About half of heating engineers dont get this right! Perhaps its not surprising because no level of technical knowledge is required before getting gas registered if you can pass the assessments.

 

[big-all]

as said simple to prove
assuming you never heat above 21 degrees
at 21 degrees you will have maximum heat loss for you house call this 100% reducing to 0 when you balance up to the outside temperature
now in the space off say 6 hrs the average temperature will be say 17 degrees and reduce the heat loss to perhaps 75% you also don't loose the say 10-15% inefficiency losses from the boiler

now what those losses actually equal will need lots off temperature figures but i would suggest 25-30% cheaper to run minus any extra losses bring back up to temperature so perhaps 20- 25% saving for timed running

 

[dhutch]

heating engineer

A term that we all know and love...

 

[Agile]

A builder who writes a column in the Telegraph is a strong supporter of constant temperature heating and published another letter and comment about this in March 2012 - http://www.telegraph.co.uk/property...08/On-the-level-Jeff-Howells-home-advice.html (second article).

Just because he writes a colluum in a paper does not mean that he necessarily understands much about heating.

He has often written many things which are not correct.

 

[Gywndy]

Just because he writes a column in a paper does not mean that he necessarily understands much about heating.

He has often written many things which are not correct.

I totally agree - that's the point I was trying to make. I challenged his comments and he totally dismissed what I was saying. Told me that if I chose not to believe it - i.e. that constant temperature heating is cheaper - then that was my problem!!

 

[75pete]

I for one, move the set point up and down during the day and subject to the weather. During very cold days, I will leave the heating at, say, 15c, ticking over during the night. The heating bills are and in my case will always be subject to the weather and our health.
Pete

 

[hazetimesfive]

what i wanna know is ... is it cheaper to run the boiler at a lower temperature but for longer, than hotter for shorter... to achieve the same 21d at home

 

[dhutch]

Again, largely, physics says it doesnt really matter what the rate you feed the energy in is to the amount you use.

Therefore the only real consideration is whether the boiler is more or less efficient at any one temperatue. To which my understanding is that, if its a condensing boiler, its worth keeping the return temperature below 55c. Boilers usally only display, or allow you to set, the out going temperature, but if thats say 65, you should acheave 10degrees drop over the radiators.

Not done any real testing on this, and dont have any boiler specific knowlage, but it seems reasonable to me.


Daniel

 

[grovesey]

I would have thought that the argument for constant heating on and in particular system on lower heat in the out of home periods,would possibly make sense in a modern extremely well insulated homes such as the north European countries. And maybe by keeping the contents in the home at a temperature where optimum comfort could be achieved by a short burst of heat would not cost too much in energy.same sort of theory to modern insulated hot water tanks and constant temp control.having said that it is difficult too see how using more energy could ever make a saving

 

[dhutch]

...it is difficult too see how using more energy could ever make a saving.

And there is a reason for that!

You are right however, that the more insulated the house, the more and more marginal it becomes, to a point where irregardless of when during the day you put in heating, the house will be warm through the day.

But certainly for my 40's council semi, even with cavity wall filling and 10inchs of glass wool in the loft, the heat ****es out really fairly fast, partiuarly on the ground floor which is mainly of a suspended construction and currently quite drafty.


Daniel

 

[Gywndy]

The guy who writes in the Sunday Telegraph is again today championing constant temperature heating! And people believe him!