What's your thermostat set at?

Cardew

The gasman,

What exactly are you saying or implying by this statement, and what have you proven?

Some people think running heating for 2 hours in morning and then 2 in evening saves money... Does it really......
Remember the fabric of the building is cold and once you have heated the internal walls etc that half the job done then all the boiler needs to do is come on for 5-10mins every hour or two to heat up 1 to 2 degrees. If your heating goes off after 2 hours the house temp plummitts down and when the boiler comes on 8 hours later the house takes a couple of hours or running to get warm and then it goes off on timer. Make your own mind up on this one but i have proven the method i use with my customers especially the elderly ones.

Let us be quite clear that it is cheaper to have the heating on for 2 hours in the morning and 2 hours in the evening, than leaving it on all day at the same temperature.

Read Energy Saving Trust or any authoriative publication. To say otherwise is to defy the laws of physics.

in_my_wellies

I9 for 1 hour am an 4 hours pm

the_gasman_2

Cardew wrote:

The gasman,

What exactly are you saying or implying by this statement, and what have you proven?



Let us be quite clear that it is cheaper to have the heating on for 2 hours in the morning and 2 hours in the evening, than leaving it on all day at the same temperature.

Read Energy Saving Trust or any authoriative publication. To say otherwise is to defy the laws of physics.

Cardew.

Thank you for your comments. I appreciate what you have to say and as i said in my post make your own minds up. However, energy saving trust has nothing to do with what we are discussing. If we all wanted to do our bit we would go with renewables or have the latest boiler/controls fitted, but we live in the real world and people will not go and pay for this. We are talkng about the room stat...

I do have qualifications in energy efficiency, but my previous post was related to my personal opinions (as someone who deals with this daily) and info i have collected from my customers and how they run their systems.

I made a statement regarding:

Some people think running heating for 2 hours in morning and then 2 in evening saves money... Does it really......

I then backed that up with what i believe to be true from many of the industries leaders of heating products and controls.

Remember the fabric of the building is cold and once you have heated the internal walls etc that half the job done then all the boiler needs to do is come on for 5-10mins every hour or two to heat up 1 to 2 degrees. If your heating goes off after 2 hours the house temp plummitts down and when the boiler comes on 8 hours later the house takes a couple of hours or running to get warm and then it goes off on timer. Make your own mind up on this one but i have proven this method i use with my customers especially the elderly ones.
Appologies for typo's. It looks like i have a proven method

Let us be quite clear that it is cheaper to have the heating on for 2 hours in the morning and 2 hours in the evening, than leaving it on all day at the same temperature

You may be quite right. I didn't say my way was the cheapest. I said this was how i run my system and recommend my customers to. Majority are home all day, pensioners who are constantly complaining of being cold. Obviously many people are out for 10 hours a day and don't wish to heat something they are not living in.

I appologise to all if my post was not clear.

Cardew

in_my_wellies wrote:

I can see what you are both saying.
When we both worked and the heating was off during the day a couple of hours in the evening and the house was nice and warm and for the rest of the evening, just coming on for a few minutes at a time. This was on Monday and Tuesday, but as the week went on, the time it took for the house to feel really warm was longer and longer and by Friday sometimes it never felt warm all through. Then at the weekend when we were in and about and the heating was on in the day that would warm the house wall so to speak, especially if we had a log fire and the warmth lasts.
Now the children are away at uni their radiators are turned off but I do make sure that either the bedroom doors are left open a couple of times a week or the rads are turned on for an evening so prevent them getting too cold and/or damp which would be more costly to heat up in the longrun. Hope this is clear.

Your point is really that the house warms up quicker the longer the heat is left on - and that is not disputed in any way. That is not the same as it being cheaper.

There is an 'Urban Myth', given credence by the post I commented on, that is somehow more expensive to heat up the fabric of a building that has been let cool down, than keeping it at the same temperature all the time.

That simply is not, and cannot be true as it defies the law of physics.

If it were true you would leave your kettle boiling all day, or saucepans simmering all day because it would cost more to heat them up from cold than leave them at the required heat.

If the argument(that it is cheaper) was valid for leaving heating on for 8 hours, why wouldn't it apply to leaving it on for 3 weeks while you went on holiday?

I also wonder how the Gasman "proves his method" especially with older customers.

EDIT
This post crossed with the last one of the Gasman.

I think we now agree that it is cheaper to have heating on a timer, but more comfortable to leave it on all the time!

in_my_wellies

I know someone who keeps the kettle full and hot all day everyday just in case someone calls. Everytime she passes the kettle she flicks it on

roswell

I find it cheaper leaving it on all the time summer and winter and just adjusting the stat between 15 and 20 degrees... depending on if im in or awake.

I know this because im on pre pay meter .. wonderfull think fo just these resons and it was costing us more having the heating on for 2 hours before the boiler shut off when we go in than to come in and wait 20 mins for the 5 degree increse.

you cant really compair a direct flame heating a pan of water to heating the materials in a house there a massive size differance for a start. then there is different conductive properties .. how will you apply physics to it ?

the_gasman_2

If the argument(that it is cheaper) was valid for leaving heating on for 8 hours, why wouldn't it apply to leaving it on for 3 weeks while you went on holiday?

I also wonder how the Gasman "proves his method" especially with older customers.

This post crossed with the last one of the Gasman.

I think we now agree that it is cheaper to have heating on a timer, but more comfortable to leave it on all the time!

Ok Cardew, I am speaking from experience and I have now justified my previous comments if you read the posts more clearly..

However, you have given us no statistical evidence that backs up your theory's and this is not a challenge to do so.

If you are in a position to be able to help members on here with stated fact and knowledge from research and development of efficient heating then please do pass on your information and i will gladly tell all people i deal with on a daily basis that we have got it wrong...

I do not wish to end up in an arguement of who is right and wrong. All I can state is documented information i have received from various courses and manufacturers i have dealt with over the years.

They all say the same.
"It is false economy to let the fabric of the building cool down."

Keep the heat on seems to be the concensus of most engineers in my industry. I am not on commission from any gas or electric companies and i certainly have not made this up.
So why are we told to pass this info on????

I am not a physician, just a humble heating engineer trying to help members on here. I can only pass on info i have been given.

And for the 3rd time I have helped some OAP's (customers) in my area to keep warm whilst keeping their bills the same. These are people who require heat most of the day and don't want large bills. I do not play with the laws of physics just the heating system and controls.

Finally, To quote a honeywell rep (heating controls) last month who has installed a programmable room stat (12 months ago) on a condensing combi. He had documented proof (gas bill for last 3 years) He has his heating on 24 hrs a day and his bill has been reduced by £8 per month(plus remeber to include gas price increases too)... Thats not fiction nor is it defying physics. Its fact.

In response to cardews earlier posts, i really would like to get to the bottom of this as i feel we all have the right to know what is the right way of saving money and energy. Wouldn't it be better to find a soloution for everyone than work against each others theory's. After all we are here to help each other save money and if i am wrong and all the above heating engineers/boiler manufacturers are wrong then there is going to be a very large humble pie to be eaten.

dc

Cardew, I must side with gasman's views and ideas, based on practice. Things have moved on, taking your views to their extreme then NEVER switching the boiler on would save the MOST money.
Heating houses is about balancing comfort and economy. Just wrapping up to keep warm is a thing of the past, though maybe coming back sometime soon.
Each house is different, each persons comfort level and pocket depth is different, each heating system has been "designed" differently, each day's weather is different. Affordability is now much more of a problem, hence this thread.

Most systems were designed for fixed boiler flow and return temps at a fixed outside temp (a few degrees above freezing) to give certain temperatures in each room. Then many approximations and spare capacity added to cope with extremes, hence the large knob on the boiler to give people some added temperature control. Rising costs have resulted in people wanting to know more on how to better control their systems efficiently.
I knew someone who would switch his cental heating off on the 1st of March and only let it come back on at the end of November. He saved money, but lost his wife and kids.

Personally, our house has had the thermostat ( mechanical type) moved from the hall into the living room and is set to give a room temp of 21 degrees checked by a digital thermometer. This was because opening the front door led to the boiler firing up, even though the rest of the house was up to temperature. thus wasting heat.
I feel the best way forward is the programmable stat, now that they are cheaper. They combine a stat with a clock, so remove the need for a timer on the system. You can set the temperature to be different at different times of the day to suit your living pattern. This ensures that in a sudden drop of outside temp that the boiler will not struggle or fail to reach the required room temperature. Whereas it would on very cold days if only on a timer.
I know that the above means the boiler is available outside Cardew's prescribed times, BUT there would be no heating useage whilst the outside temp was above that set as minimum on the programmable stat, and so no waste.

Cardew

dc wrote:

Cardew, taking your views to their extreme then NEVER switching the boiler on would save the MOST money.

Yes you are absolutely right; it would obviously be the cheapest way! Where you are totally wrong is in attributing to me views that I have never expressed. Namely that I am advocating a particular method for anyone to operate their CH system.

I really don’t know how often I have to make the point that I am talking about the cost of running a CH system, and NOT commenting on how someone should run their system. Of course it is a compromise between cost and comfort and I have my CH switched on constantly when I am in the house, but accept that it will cost me more than having it off for a period.

The crux of this argument is that it costs more to heat up the fabric of a cold house than to keep it at a constant temperature; it does not!

Again let me state unequivocally that if the Gasman’s colleagues say it is cheaper to keep the heating on constantly(and I don’t think they say any such thing) they are wrong!!
The (mis)quoting of a Honeywell rep's case is exactly the sort of flawed logic used to support such arguments. For the purpose of this discussion, a programmable room stat used properly achieves the same objective as a timer. However if it is set to keep the house at a constant temperature ......

The Gasman, If you want proof which is cheaper – go and read the laws of physics! If you can't understand them - find someone who can; don't rubbish them as they have stood the test of time.

Second law of thermodynamics: The rate of heat loss is directly proportional to the difference in temperature between the two bodies being considered (the house and outside).

Corollary: More energy is therefore lost to the surroundings in a given time if a body is held at an elevated temperature than if it were allowed to cool.

First law of thermodynamics: The more energy lost to the surroundings, the more energy is required to return to that same elevated temperature (or maintain the temperature).

Conclusion: More energy is consumed in maintaining an elevated temperature than allowing a body to cool before reheating it.

Or perhaps the read the Energy Saving Trust(EST) statements on this subject. For those who aren’t aware the EST is a Government sponsored organisation that is the authority on these matters. The extract below is from their 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.

Question

What’s the best way to control a central heating system?

Answer

An effective central heating system should have control over both the temperature within the dwelling and the times when the system is in use.
Room thermostats and thermostatic radiator values in the bedrooms will control the temperature in each room. A cylinder thermostat should also be fitted if you have a hot water cylinder. This will ensure that the hot water remains at the temperature you require and doesn't get too hot. These controls will ensure that your house is heated to the temperature you prefer whilst time controls will determine when you require the heating. Time controls are normally set to switch the system on when you need it and turn it off when you don't, thereby saving you fuel and money. Combined hot water and heating controls allow you to switch on each system independently to provide maximum efficiency.

I really don’t think you can get anything much clearer than that.

So if we are to have any further discussion on this subject please let us have it based on some facts and do not misquote what I have said. To repeat:

I have simply stated that it is cheaper to have the heating on a timer, rather than leaving it on constantly.

It is an urban myth that it costs more to heat up the fabric of a cold house, than keeping the house at a constant temperature.

I am not advocating that you should compromise comfort for cost.

Lastly how anyone heats their house is up to themselves; but to keep it at a constant temperature is NOT cheaper and people shouldn’t offer advice that cannot be supported.

Madiba_2

Chill out people (get it!?)!!

I leave my CH on all the time, because I am in all the time. I have the thermo set to 18 in the day and 12 at night. I know this isnt very useful info as each house is different.

I have about 2' of insulation in some parts of the loft, I think that helps!!