tinfoil down the back of a radiator ??..

[Darcydog]

Originally Posted by another_clean_sheet

Well my heating goes off in the evening shortly before I go to bed and comes on about half an hour before I get up in the morning. I live in a 300 year wood framed cottage so insulation is not the best so last night when the outside temperature dropped to -4degrees, the lounge dropped to 16.2 degrees. Upstairs would be obviously warmer. There was no condensation on any of the double glazed windows in the morning.

At the moment the lounge is at 19.8 degrees and the humidity is at 48%. Ideal humidity is considered to be between 40% and 60%
All achieved without dehumidifiers and heating the house 24/7

Excellent!

Sounds like your house is running nicely.

But can I be devils advocate and ask you how much “extra” it would cost to keep your lounge at 19.8 24/7 rather than allowing it to cool by 3.6 degrees C and then expending energy all in one go to get it back up to 19.8deg C again ?

[another_clean_sheet]

Originally Posted by Darcydog

Excellent!

Sounds like your house is running nicely.

But can I be devils advocate and ask you how much “extra” it would cost to keep your lounge at 19.8 24/7 rather than allowing it to cool by 3.6 degrees C and then expending energy all in one go to get it back up to 19.8deg C again ?

I do not know. The only way to prove whether 24/7 heating is cheaper or not is to do a controlled experiment. This would need two identical houses (layout, materials, insulation, heating systems etc) in the same location so external conditions are the same and run from Sept to March.
My house heats up quickly in the morning as you would expect as the thermal capacity of a roomful of air is small. During the day there will be some warming of the structure of the building but I believe this is small as solid/gaseous interfaces are not good for heat transfer and before it has warmed the structure fully the heating will go off for the night.

[klarzy]

This keeps me warm all year round....

[Avulon]

Originally Posted by another_clean_sheet

Those that have studied physics will know that heat loss is affected by a number of variables - the difference in temperature either side of the boundary, the area of the boundary, the thickness of the boundary and the thermal conductivity of the boundary.
This is expressed as the formula :
Q/t = KA (T1 -T2)/d
Q/t = rate of heat transfer - joules/sec or watts
K = the thermal conductivity of material that the heat is going through
A = the area
d = thickness of the material.
T1 & T2 is the internal and external temperature
In the case of a house the only variable is T1 & T2

Now if the house is maintained at a constant temperature then the heat loss is constant (assuming outside temperature does not change).
However if one only heats the house when it is occupied then the heat loss will drop with time as T1 reduces.

Can't pick fault with that

Originally Posted by another_clean_sheet

The thermal mass of air in the house is small and when the heating comes back on then the heat required to bring room upto temperature is less than the heat loss if you were heating it 24/7.
I have ignored the effect of dew point temperature.
This is not subjective but scientific fact

Can pick fault with this. This conclusion is a sweeping generalisation based on assumptions for the value of K and the period that the house is left unoccupied (i.e. unheated). The worse the insulation, and or the longer period of being unheated the more likely to be true this is.



Anyway - another log on the fire and put me feet up.

[Avulon]

Originally Posted by Avulon

Can't pick fault with that






Can pick fault with this. This conclusion is a sweeping generalisation based on assumptions for the value of K and the period that the house is left unoccupied (i.e. unheated). The worse the insulation, and or the longer period of being unheated the more likely to be true this is.



Anyway - another log on the fire and put me feet up.

PS. This is why modern heating systems are equiped so that the heating doesn't turn off (truly off) but is intended to go to a setback heat value during the unoccupied period. All homes differ in what the suitable setback temperature is. The time taken to heat from the setback temp to the 'normal' occupied temperature should be setup on the timer for the best comfort of the occupants when they are home: i.e. if setback temp is 16 and comfort temp is 21 and it takes an hour to elevate the temp from 16 to 21 then the heating should switch to 21 an hour before the occupants would be expected home.... Or just get used to 20 degrees and leave it at that 24/7.

[Darcydog]

Originally Posted by another_clean_sheet

I do not know. The only way to prove whether 24/7 heating is cheaper or not is to do a controlled experiment. This would need two identical houses (layout, materials, insulation, heating systems etc) in the same location so external conditions are the same and run from Sept to March.
My house heats up quickly in the morning as you would expect as the thermal capacity of a roomful of air is small. During the day there will be some warming of the structure of the building but I believe this is small as solid/gaseous interfaces are not good for heat transfer and before it has warmed the structure fully the heating will go off for the night.

No - a simpler way is to do what we did when my wife required a warm home 24/7 during her recuperation.

We found that the cost was the same - it made not a jot of difference to our costs - BUT! - we were warm all the time - morning and during the day, evening and at night.

All at no extra cost.

And yet you do the classic cop out and say that ‘the ones ly way to prove you are wrong is by having identical houses, blah blah blah blah blah....

In other words rather than you admit that I and many other “converts” might have a point - you set up some extreme conditions where only if these parameters can be set up within a randomised, double blind, placebo controlled study would you accept that heating up a house you have let get cold requires much the same energy as maintaining that same house at a comfortable temp. For the same given weather conditions.

Sorry - but you make me laugh!

[another_clean_sheet]

Originally Posted by Darcydog

No - a simpler way is to do what we did when my wife required a warm home 24/7 during her recuperation.

We found that the cost was the same - it made not a jot of difference to our costs - BUT! - we were warm all the time - morning and during the day, evening and at night.

All at no extra cost.

And yet you do the classic cop out and say that ‘the ones ly way to prove you are wrong is by having identical houses, blah blah blah blah blah....

In other words rather than you admit that I and many other “converts” might have a point - you set up some extreme conditions where only if these parameters can be set up within a randomised, double blind, placebo controlled study would you accept that heating up a house you have let get cold requires much the same energy as maintaining that same house at a comfortable temp. For the same given weather conditions.

Sorry - but you make me laugh!

Glad to make you happy.
However as someone with a honours degree in science one learnt that the only way to prove facts like this was to do a controlled experiment. One reads all about them all the time with experiments with food, supplements, diets, exercise etc as one group continues as before and the other group undertakes the experiment. The groups need to be large enough to take out any variability.

[Les4048]

Jeez and to think this is all started with a simple question about tinfoil behind a radiator

[Darcydog]

Originally Posted by another_clean_sheet

Glad to make you happy.
However as someone with a honours degree in science one learnt that the only way to prove facts like this was to do a controlled experiment. One reads all about them all the time with experiments with food, supplements, diets, exercise etc as one group continues as before and the other group undertakes the experiment. The groups need to be large enough to take out any variability.

Indeed - mine is in Microbiology and Biochemistry. But please be honest here. You are hiding behind a reasonable and required scientific principle as a dubious construct such that you don’t have to admit you just might be wrong.

The principle I am asking you to state your opinion on is a simple one - namely

“What would the difference in energy cost/usage be to maintain a given house at 20degC 24/7 or - allow it to go cold for lengthy periods and then have to expend energy to re-establish the desired temperature?”

That is the basic question.

Secondary questions are to do with the comfort benefit that 24/7 heating provides that help even more. In particular 24/7 heating has the huge benefit of drying a home out. Low relative humidity = a more comfortable environment.

Whereas a heating cooling heating cooling cycle actually generates condensation


E

[Number 6]

So to sum up.

Does putting a tin foil covered panel behind the radiator do any good ??