Keeping central heating on all the time?

tomstickland

I think we need a cooling off period on this.

ariba10

tomstickland wrote:

I think we need a cooling off period on this.

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Ouch!

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masonic

shelly wrote:

OK. I have just shown hubby this thread and he's explained to me what we do.

Thanks for clarifying that, shelly. It sounds like what you are doing is only subtly different from running a timer in the normal sense.

Cardew

masonic wrote:

Thanks for clarifying that, shelly. It sounds like what you are doing is only subtly different from running a timer in the normal sense.

A much more diplomatic way of saying Shelly was completely wrong in her backing of Kat21.

kat21.....I'd give up now.... You know it works and so do I. You aren't going to change these peoples minds

Actually Shelly was quite right in one respect - 'these people' didn't change their minds.

masonic

Cardew wrote:

A much more diplomatic way of saying Shelly was completely wrong in her backing of Kat21.

Well at least she came back to set the record straight. Plenty of people wouldn't have bothered. There's no point in dwelling on a mistake, Cardew.

Skiduck

Every single household is different, due to way different people live, you can't accurately predict heat losses - this is where everyone's argument has valid and invalid points.

For example, someone leaving their heating on 24/7 is concious of that and if they are prudent, will have heat losses for each room in their minds if they believe it is conserving fuel. However, someone may leave their heat on 24/7 and have no respect for any heat losses, thus wasting energy. This is the main reason why the heating industry can not generalise this subject or advocate a notion of leaving heating on 24/7. Mears calculators, that calculate heat losses in a given room are set up to slightly over compensate and installers will always add a bit more to the heat loss calculation in order to specify the heat input required - to put it simply, you can always turn the heat down but can never add more heat than what is installed unless you provide a secondary heat source - ie a fan or the like.

There are so many factors to consider in this argument that the only way to tell if it is feasible for you is to test it.

it may work for some people but not for others - that's the bottom line.

masonic

Skiduck wrote:

Every single household is different, due to way different people live, you can't accurately predict heat losses - this is where everyone's argument has valid and invalid points.

I think what you are saying is basically that someone could be using heating wastefully on a timer and then see an apparent saving if they then put their heating on 24/7 but use it conservatively. Of course, this will result in their bills coming down, but it does not mean that they are using their heating most efficiently. Personally, I cannot understand how it would be easier to turn a thermostat down AND leave ones heating on 24/7 rather than just turn the thermostat down. To that end, the whole concept of leaving heating on is a red herring in that argument as far as I can reason.

Skiduck wrote:

Mears calculators, that calculate heat losses in a given room are set up to slightly over compensate and installers will always add a bit more to the heat loss calculation in order to specify the heat input required - to put it simply, you can always turn the heat down but can never add more heat than what is installed unless you provide a secondary heat source - ie a fan or the like.

There are so many factors to consider in this argument that the only way to tell if it is feasible for you is to test it.

The whole argument against leaving heating on is driven by the premise: the hotter a room is, the faster it loses heat. No possible factor I'm aware of changes that. Cold rooms do not and cannot lose any heat, and energy loss approaches zero as rooms cool to match the temperature outside.

There are no naturally occurring physical processes that result in rooms losing negative amounts of heat to colder surroundings, so the notion that less energy is lost by keeping a room warm is, as far as I see it, completely absurd regardless of any special circumstances.

Skiduck

masonic wrote:

I think what you are saying is basically that someone could be using heating wastefully on a timer and then see an apparent saving if they then put their heating on 24/7 but use it conservatively. Of course, this will result in their bills coming down, but it does not mean that they are using their heating most efficiently. Personally, I cannot understand how it would be easier to turn a thermostat down AND leave ones heating on 24/7 rather than just turn the thermostat down. To that end, the whole concept of leaving heating on is a red herring in that argument as far as I can reason.


The whole argument against leaving heating on is driven by the premise: the hotter a room is, the faster it loses heat. No possible factor I'm aware of changes that. Cold rooms do not and cannot lose any heat, and energy loss approaches zero as rooms cool to match the temperature outside.

There are no naturally occurring physical processes that result in rooms losing negative amounts of heat to colder surroundings, so the notion that less energy is lost by keeping a room warm is, as far as I see it, completely absurd regardless of any special circumstances.

no, you misunderstand me - as I said, people live in different ways and have different insulation/glazing/heating set ups etc etc - (again like I said - too many factors, including what direction your lounge is facing). That is why I said that no one will claim that leaving the central heating on 24/7 at a certain temp. is better than using a timer. You can lose a lot of heat for many reasons and keep heat in for many reasons, let me give you some:

curtains
conservatories
draught excluders
draughts
single glazing
double glazing
cavity wall
cavity wall insulation
solid walls
chalk walls
loft insulation
loft hatches
loose tiles
solid doors
doors open
open plan stairs
utility rooms
concrete floors
laminate floors
wood floors
carpets
above door windows


I could go on, but hopefully you get what I mean - these are factors that are static in any household, other factors include the lifestyle and appreciation of heat losses which is dependent on the preceding factors. As I said before, it may in some cases albeit small, be beneficial, in most cases it won't and that is why the industry will not enter into the argument to set any precedent.

I don't understand when you say "there are no naturally occuring processes that result in rooms losing negative amounts of heat to colder surroundings", do you mean that heat with not dissipate to a colder area? It does, but the major force in heat is the rise, however radiation is sometimes a "by product", if you will, of convection, so heat will dissipate other than upwards, and insulation makes sure convection remians "local"

masonic

Skiduck wrote:

...As I said before, it may in some cases albeit small, be beneficial...

I totally disagree with that for the reasons I've outlined above. Specifically, "hotter a room is, the faster it loses heat. No possible factor I'm aware of changes that". A room being held at a constant elevated temperature will always lose more heat than the same room that is cooling from the same initial temperature.

Edit: Just to expand... this is a statement of Fourier's Law.
Fourier's Law can be expressed as Q = UA(T2-T1)
Where Q = heat loss, U = thermal conductance (U-values, anyone? ), A = Area and T2 and T1 are the internal and external temperatures.
'U' can be expressed as a total for a room/house and is a constant. 'A' is also a constant. This is in essence exactly what you have already stated to be true.
Therefore - (T2-T1) is directly proportional to the heat loss to the surroundings. The bigger the difference in temperature, the greater that heat loss.

Skiduck wrote:

I don't understand when you say "there are no naturally occuring processes that result in rooms losing negative amounts of heat to colder surroundings", do you mean that heat with not dissipate to a colder area? It does, but the major force in heat is the rise, however radiation is a "by product" if you will of convection, so heat will dissipate other than upwards, and insulation makes sure convection remians "local"

What I mean is, paraphrasing, a cold room will not lose any heat. In order for a warm room to lose less heat than a cold room, it would have to absorb heat from its colder surroundings, which is not possible.

It might be better to consider the whole house in this instance.

Skiduck

"I totally disagree with that for the reasons I've outlined above. Specifically, "hotter a room is, the faster it loses heat. No possible factor I'm aware of changes that". "
so a hotter room above and adjacent that that room will not do anything?

"It might be better to consider the whole house in this instance. Insulation is never 100% efficient, so even heat loss through insulated bodies always occurs." the main heat loss in any house is through the roof.

"What I mean is, paraphrasing, a cold room will not lose any heat. In order for a warm room to lose less heat than a cold room, it would have to absorb heat from its colder surroundings, which is not possible. " no, it will loose heat through radiation the same as a cold room, but if a cold room has an ambient external temperature less than the warm room has, it will loose heat at a lesser rate.

I am not saying that leaving it on 24/7 is prudent by any means, but it is possible in some limited cases. You have to consider the radiation, convection and heat losses horizontally.