What's the cheapest way to run my heating?

Dunroamin

ian103 wrote: »

Next house, a lot older, built with no consideration to insualtion and we started running it as EST suggest, it didn't really work satisfactorily for us, so on advice from a heating engineer we had a new thermostat installed - it had two settings 'low and high' we set that at 14 and 20deg C, we then ran at 14degC at all times even in the summer, and boosted when we sat down at night AND we never looked back, the house was always comfortable and it suited us.

You had the central heating on permanently all summer?:eek: You must have been so uncomfortable!

Leif

Avoriaz wrote: »

I read them.

There was a lot of conflicting advice and comments and the question had not been answered conclusively.

Aha, silly me, it is only conclusive when you post. All other posts are invalid. There we go, the oracle speaks. I am not worthy.

Avoriaz

StuC75 wrote: »

What about if the drop in temp is more than 14-16.. What if unheated the house temperature say dropped to 9/10 (in winter when freezing outside).. How much more energy is taken to return from 9 to 14 then back up.. agree that if would only drop to 14 that its rather 'futile' to give the short reheat - but what if a higher range of temperature would be observed…....

The same principles apply.

Plus, my example ignored heat gradients for simplicity. The colder it is outside the higher is the temperature gradient and the more quickly heat is lost.

Keeping the heating on low, regardless of the outside temperature, means that more heat is being lost than if the heating is off. The effect is greater the colder it is outside. Thus, the colder the outside temperature, the more heat, and therefore money, is wasted by keeping the heating on low.

Remember that I am considering the lowest cost answer, not the one that is more comfortable or more convenient, as that is what the OP asked for.

Avoriaz

StuC75 wrote: »

..Interested to note your view of a Thermostat with 2degree tolerance is more effective than continuous off/on (shorter tolerance); as just gone through a year with a vokera wireless model thats been expensive on the gas compared to a previous house with a more featured programming - and strongly looking to replace that!..

A typical thermostat would be designed to switch on when the temperature drops a certain amount below the set point on the thermostat, and switched off when it rises a certain amount above. That is called hysteresis and it prevents excessive switching.

I’m not suggesting that 2 degrees is ideal, I merely used it as an example, although it probably isn’t too far from the norm.

Thermostats can do all sorts of clever things, such as slightly heating the air around the sensor to reduce cycling, but none of that is particularly relevant here. All we need to consider is that they can switch the heating on and off at a user controlled temperature.

Avoriaz

Leif wrote: »

Aha, silly me, it is only conclusive when you post. All other posts are invalid. There we go, the oracle speaks. I am not worthy.

Why be sarcastic and unpleasant. I wasn’t sarcastic or unpleasant to you.

As far as I recall, you agreed that leaving the heating off was more cost effective.

I didn’t claim that my answer was definitive, It was merely an attempt to provide a simple example to aid the OP.

If you don’t like my posts, you are not compelled to read them.

southcoastrgi

Ok I am prepared to learn something here (I know shock horror), in your 14 degree example, if the outside temp was constant at 14 would the internal temp of the house not drop below this ? As in the same way insulation keeps heat in would it not also prevent the heat from outside getting in ? So would the internal heat not be lost to the fabric of the building therefore the internal temp will be less than outside, in the same way as a north facing room is always colder than a south facing one.

cyclonebri1

Leif wrote: »

Aha, silly me, it is only conclusive when you post. All other posts are invalid. There we go, the oracle speaks. I am not worthy.

Leif, it's my turn to advise you that it is time to leave it

There's a quote from the classic film Cool Hand Luke, and also sampled on a Guns & Roses album;

to cut it short "there's some fellas you just can't reach", oh, I should add, it starts;
"wwwhat we got here is ..... failure to communicate"

It often springs to mind

Avoriaz

keithgillyon wrote: »

Ok I am prepared to learn something here (I know shock horror), in your 14 degree example, if the outside temp was constant at 14 would the internal temp of the house not drop below this ? As in the same way insulation keeps heat in would it not also prevent the heat from outside getting in ? So would the internal heat not be lost to the fabric of the building therefore the internal temp will be less than outside, in the same way as a north facing room is always colder than a south facing one.

In simple terms no.

Heat energy always seeks equilibrium.

Insulation only slows down heat transfer, it doesn't stop it.

If the ambient outside temperature is a steady 14, then a house will eventually settle at 14 too as the air takes heat from the house. The house can’t sink below 14 if there is nothing colder than 14 to take heat from it.

In reality things are far more complicated.

A house will usually be generating some heat energy. All the numerous electrical devices in the house such as fridges and freezers, clocks, audio and video devices even in standby, mobile phone chargers left plugged in, security lights left on, heating timers etc, will generate some heat. Cats, dogs and other pets left inside will produce heat. Even the spiders and insects in there generate a tiny bit of heat. Houses may even also contain small amounts of radioactive material that generate tiny amounts of heat.

Sunlight, even on cloudy days will also input heat into a house, both via windows and via the external brickwork, roof etc. (More on south facing and less on north facing to answer that bit)

But for simplicity you can more or less ignore all of that and assume that a house will always be trying to be at heat equilibrium with the air surrounding it.

If it is 14 degrees outside your house will cool to 14 degrees in the absence of any heat source.

Everything in the world continually tries to be at heat equilibrium.

The universe itself will eventually reach heat equilibrium and all life and motion etc will cease. That last bit is a few years away and is disputed by some. MSE will have long gone by then.

Jaynne

keithgillyon wrote: »

Ok I am prepared to learn something here (I know shock horror), in your 14 degree example, if the outside temp was constant at 14 would the internal temp of the house not drop below this ? As in the same way insulation keeps heat in would it not also prevent the heat from outside getting in ? So would the internal heat not be lost to the fabric of the building therefore the internal temp will be less than outside, in the same way as a north facing room is always colder than a south facing one.

In thermodynamics basically everything wants to return to absolute zero however there are a lot of heat sources in the universe. The most obvious one you see (most days in the UK) is the sun. The outside of your house is always going to have more capacity as it were to soak up temperature changes (think of putting a drop of dye in a glass of water or the bath tub where do you notice the dye most). So your house in the absence of any cooling or heating will always be returning to the temperature of the outside.

If for some reason your house went below the outside temperature, maybe you put some air conditioning on, the opposite to when your heating is on will take effect - the warm air outside will rush into your house.

So yes insulation works both ways and an air conditioner like a heating system will be more efficient when there is more insulation.

cyclonebri1

I have to say that inspite of the internal disputes this has been a fascinating thread, :T:T:T, I've learnt from it and for me it supports my anecdotal findings, cheers all.