How should one maintain the temperature in the house??

lightSwitch_3

I've been trying to figure out which way is best to heat my house so the boiler does the least amount of fuel munching.

So here is my question ( especially for winter scenarios)
Should I allow the house temperature to go to as low as it will go when I don't need a heated house, like sleep time and work time then put the boiler on to bring it up to the temperature comfortable for me which is 18 degrees or should I not allow the house to go below a certain temperature say 16 degrees then bring it up to 18 when I'm at home? Which way is more energy efficient?
I need 18 degrees from 7am to 9am and from 6pm to 11pm

Can people mention what temperatures they run their house at please?

KimYeovil

:wall: :wall: :wall:
_pale_ _pale_ _pale_

savers_united

I have a room stat set at 18 degrees, I use approx 5 units (55kWh) on a typical winters night (4pm - 10pm).
However if on the weekend I have the heating to come on at 9am and go off at 10pm with the same 18 degree setting I usually use the same or less gas.
From my observations it seems that the largest amount of gas is used getting the house to temp, i.e 16degrees at 4pm then 18degees by 5.30pm having used 2 units of gas.
After this the system ticks over using 0.75 unit per hour upto 10pm.

However switch it on at 9am and its up from 16degrees to 18degress within the hour and only 1.5 units used, it then just ticks over at approx 0.3units per hour until 10pm maintaining the 18 degrees.
It seems if I can get the house up to temp duing the day when outside temps are higher the system does not work so hard at night when the temp falls.

Cardew

"Allow the house temperature to go to as low as it will go when I don't need a heated house, like sleep time and work time then put the boiler on to bring it up to the temperature comfortable for me which is 18 degrees."

Exactly that!

Absolutely no question that is the most energy efficient way.

There should be no further discussion on this issue - but everytime this question is asked(which is frequently) someone will trot out the urban myth that it takes more energy to heat a house from cold than keep it warm.

That gem of information will have been gained from a bloke down the pub whose dad is a plumber.

Next we will have those who have tried both methods and know it is cheaper to have the house up to temperature 24/7 and it doesn't matter that it defies the laws of physics - cos that's only theory.

EDIT
Beaten by 2 minutes!

Cardew

savers_united wrote: »

I have a room stat set at 18 degrees, I use approx 5 units (55kWh) on a typical winters night (4pm - 10pm).
However if on the weekend I have the heating to come on at 9am and go off at 10pm with the same 18 degree setting I usually use the same or less gas.
From my observations it seems that the largest amount of gas is used getting the house to temp, i.e 16degrees at 4pm then 18degees by 5.30pm having used 2 units of gas.
After this the system ticks over using 0.75 unit per hour upto 10pm.

However switch it on at 9am and its up from 16degrees to 18degress within the hour and only 1.5 units used, it then just ticks over at approx 0.3units per hour until 10pm maintaining the 18 degrees.
It seems if I can get the house up to temp duing the day when outside temps are higher the system does not work so hard at night when the temp falls.

Can we take this one step further.

If you were to leave your house for say 10 years. Would you find it cheaper to keep the heating on for those 10 years, rather than heat it up when you came back?

How about 1 year?

1 month?

1 week?

A day?

12 hours?

6 hours?

It is all exactly the same principle and governed by the laws of thermodynamics. i.e. a warm body(the house) loses energy(heat) at a faster rate than a cooler body.

The other analogy often used is why don't you keep the kettle simmering all day? If it takes more energy to heat it up from cold.

I am not trying to be insulting, but you cannot be serious if you believe you can heat the house for an extra 7 hours at the same temperature and "use the same or less gas." Why don't you leave it on an extra 10 hours and you will save even more gas.

savers_united

Cardew wrote: »

Can we take this one step further.

If you were to leave your house for say 10 years. Would you find it cheaper to keep the heating on for those 10 years, rather than heat it up when you came back?

How about 1 year?

1 month?

1 week?

A day?

12 hours?

6 hours?

It is all exactly the same principle and governed by the laws of thermodynamics. i.e. a warm body(the house) loses energy(heat) at a faster rate than a cooler body.

The other analogy often used is why don't you keep the kettle simmering all day? If it takes more energy to heat it up from cold.

I understand where your coming from, but from my experience with a large 4 bed 1960s property is better to maintain the temperature then work the boiler hard to get the house up from a low temp.

The example i would use is, if I was to get the house up from 16degrees at 9am to 18degrees at 11am and then switch the system off and then back on again at 1pm at 16 degrees and off again at 3pm at 18degrees and back on again at 5pm at 16degrees and back off again at 7pm at 18degrees and back on again at 10pm at 16degrees and off again at 12am at 18 degrees I would of probably used 8units of gas as my system will use approx 2 units to get from 16 - 18degrees depending on outside temp, however get it up to temp once using the 2 units and it will stay there by only using a small amount each hour.
All walls in the property remain warm, where as switching on / off every couple of hours and the walls remain cold as if the fabric of the property is not being warmed, however once the walls are warmed with the heating constantly on controlled via a room stat the property remain more comfortable and not much inconsistency in heating.

The other analogy often used is why don't you keep the kettle simmering all day? If it takes more energy to heat it up from cold.

We have just had all kettles in work removed and replaced with hydro boils, these are wall mounted boilers that deliver instant boiling water, supposed to be more energy efficient than boiling a kettle a number of times a day.

Check them out
http://www.dealec.co.uk/acatalog/zip_hydroboil_range.html

Cardew

This could go on and on.

Firstly the water boilers at work. Read the brochures. These store huge quantities of boiling water 10 litres or much more. They take something like 30 minutes with a 3 kW element to bring up to temperature and take energy(electricity) to keep them at that temperature. They are used for time saving and convenience, the energy efficiency over kettles comes from insulating the water tank.

You are getting confused between what is more comfortable and convienient and better, with what is more economical.

Take your scenario of up to 18C and down to 16C etc It is an absolutely inescapable fact that the rate of heat loss from your house when at 18C is higher than when it is at 16C. So keeping it at 18 will take more energy.

If this wasn't the case why not keep the house at 28C and walk round in swimsuits all day.
You really can't have it both ways, if it is more economical according to your theory to keep the house at 18C rather than let it drop to 16C, then it must be more economical to keep the house at 28C rather than let it drop to 18C!!

Honestly you are wrong - look at any publication like the Energy Saving Trust and it will tell you that you are wrong.

Totality

savers_united wrote: »

We have just had all kettles in work removed and replaced with hydro boils, these are wall mounted boilers that deliver instant boiling water, supposed to be more energy efficient than boiling a kettle a number of times a day.

Check them out
http://www.dealec.co.uk/acatalog/zip_hydroboil_range.html

We chucked the kettle and got a Tefal Onecup.

Re the original topic. Sounds a bit like people who say boiling water from cold when cooking is quicker than boiling it from warm/hot to me.

lightSwitch_3

Cardew,
I've not been able to find any website Energy Saving Trust included that answers this question.
I think the answer lies in how well your home is insulated to start with. Do you agree or are the laws of thermodynamics against this one aswell?

Cardew

lightSwitch wrote: »

Cardew,
I've not been able to find any website Energy Saving Trust included that answers this question.
I think the answer lies in how well your home is insulated to start with. Do you agree or are the laws of thermodynamics against this one aswell?

Lightswitch,

The laws of thermodynamics are the laws of thermodynamics - full stop!

It doesn't matter how well your house is insulated, the heat loss from a warmer house will be greater than from a cooler house - full stop!

When the temperature inside the house reaches the same temperature as that outside the house, there will be no heat loss.

The standard of insulation will affect the rate of heat loss - open your doors and windows and your rate of heat loss will be greater.

This is an extract from faq on the EST website.

Question
Is it more economical to leave my heating on 24hrs in the winter?

Answer
No. It is a common misconception that it is cheaper to leave your hot water and heating on all the time. Boilers use more power initially to heat water from cold, however the cost of this is greatly exceeded by the cost of keeping the boiler running all of the time.

The best solution is to programme your heating system so that it comes on when you need it most (possibly early morning and in the evening), and goes off when you don't need it (when you are out of the house or asleep). There are a range of controls that can be used and your heating engineer will be able to provide you with the most appropriate solution.

Depending on your circumstances it may be necessary to keep the heating on all day during winter but it will cost more than if you turn the heating off when you don't need it.

lightSwitch_3

Cardew,
I see the logic in that, it sounds like a concentration gradient or osmosis. I can also see that in a well insulated 4 bed house to get the temperature up to say 18 degrees will not take that long perhaps 45 mins or less.