Probably stupid question about this keeping the heating on constantly at 16 degrees thing

[virgiltracey]

how do I do this if I don't have a thermostat? We have thermostatic valves on the radiators but no room thermostats? Will I still get the same benefits/savings if I have the heating on constantly but the radiators all on low or not? I'm a bit confused since presumably a room thermostat turns the boiler on and off whereas presumably a radiator thermostat just lets more hot water in (but its constantly being heated)???!! .

We MUST get our oil bills down this year and so any other heat/money saving tips gratefully received!

no, that isn't true.

The amount of energy required to bring it back to temp will always be less than the amount of energy needed to maintain it.

no, it can't always be.. you'd have to do the sums to work out where it crosses over... becasue the house temperature does not drop linearly and unlimited.. it only goes down to about 12deg usually, this is the temperature of most caves. it will go lower a bit in the depths of winter but not unlimitedly low.

yes, the amount of energy required to reheat it after allowing it to go cold is always lower than the amount of energy required to maintain the temperature.

I am not talking about internal comfort, I am talking about the amount of energy (electricity or gas) required and therefore the cost.

You're welcome to try to compose a case where it isn't.

p.s. if you're talking about fuel costs at higher or lower temperatures, that is a different question.

Thank you PigletJohn for putting this myth straight. I have lost count of the number of times I have been told that it is cheaper to leave the heat on low all the time than have it at a higher temperature several times a day. The reason people appear to save money is presumably because they've turned the heating down! If you turn it down AND having it on just when you need it, you'll save even more money!

well, I'd normally say set the timer to restart the heating half an hour before you come home or get up, and go off half an hour before you go to bed. A well-insulated, draught-free house will cool down slower, and heat up faster so you can adjust those times. When I had cavity-wall insulation installed the cool-down changed from something like half an hour to something like 3 hours (I noticed that if I came home at lunchtime the house was not cold, I didn't meaure it accurately).

Thank you pigletjohn. I shall look into getting room thermostats.

(You'll also be pleased to know that the moneysavingexpert website has a big article on the front page which also sets the record straight on heating the house and confirms that you are right and it is not cheaper to have the heating constantly on low!!)
We have had cavity wall insulation installed over the summer and so I shall be looking to see whether that makes a difference to the oil consumption this year. DH has also added space blanket loft insulation which has fluffed up to about a foot thick. I have fleece lined all our curtains and have made draft excluders for all the external doors. Hopefully we shall save a bit of money this year since I can't keep using two an a half 2500 litre tanks of oil every year!

that sounds great virgil, you seem to have done all the major things. I bet you will find they make a big difference to comfort and energy use. Do please remember to come back and tell us how much oil you use.

Did you find that the new fibreglass insulation does not shed dust and itchy fibres?

You might think about heavy curtains with Portiere rods over the front and back door (this is a hinged and sliding curtain rod that swings open with the door, although it is fixed to the wall as well at one end). The big advantage is that you can open the door from either side, without having to open the curtain first. This can prevent the hall getting so cold.

Another quite big job, if you can crawl about under the ground floor, is to put insulation quilt between the joists. This will cut down draughts and cold surfaces from the floor, especially if you have any exposed floorboards. It is a bit grimy and usually a cramped job. Heat loss through floors is not as great as through the roof, though, so this is not as urgent as the work you have already done.

You can set the new stats for an overnight temperature of 12C or something, just so it never gets icy cold at night, but with your new insualtion you will probably find it practically never gets that cold, so it will simply leave the boiler turned off unless required. It is looking as if this winter will not be as bad as last year.

I do hope you're right about this winter. We live in the middle of a wood and it gets freezing here. Last year we were snowed in for five days and so I'm determined to at least be warm even if we are housebound!!!!

And yes the space blanket insultion was really easy and fibre free once we realised how to unroll it without ripping the foil. I was amazed at how much it fluffed up!

PigletJohn - I have a question. I have TRVs fitted to all my rads but a lot of them are broken so that if I turn them down, the radiator is still boiling hot. I have a mate who is a plumber coming round to look at them but is there any way I can turn them off (in rooms I don't use) in the meantime? I've tried turning round the little stick that goes into the TRV but that doesn't seem to have any effect

yes

at the opposite end to the TRV is another valve. It is called a lockshield valve because it is supposed to have a screw-on cover which prevents you fiddling with it. If you take this off (usually a screw in the middle of the top, and then the plastic dome lifts off) you will find a spindle which can be turned to open or close the valve.

This valve ought to have been adjusted so it is almost closed, usually less than a full turn open from the fully closed position. You can turn it with a new knob, or with a very small adjustable spanner. You can buy replacement universal radiator valve knobs at DIY sheds and plumbers merchant, the fitting will vary according to the make, but the universal ones usually contain a selection of fittings. If you are using an adjustable spanner, make it a very tight fit or you will burr and round off the brass spindle.

If the valves are very old, they might leak round the spindle when disturbed. If so, winding them down to the fully closed or the fully open position will usually stop it. Have some kitchen roll and old towels handy just in case. Water in radiators (unless they are very new, or have been religiously treated with corrosion inhibitor,) will be black with iron oxide, as a result of the steel rads corroding. This will stain carpets and ceilings and is pretty well impossible to remove, so take it seriously. if the valves are less than ten years old, they ought not to leak. If they are 30 years old they almost certainly will.

As for your TRVs, if they are a major brand, you can probably still buy replacement thermostatic heads to fit. Top brands are Pegler, Danfoss and Drayton. The head can be removed by unscrewing a large horizontal nut or knurled ring below the head. No water comes out. However, due to volumes of sales, a replacement head will probably cost more than a complete new valve. However it is much more work to change the complete valve and you will be letting water out. If you have more than two or three to change, a plumber will probably drain the entire system, and do a houseful in a working day. In this case you might as well renew all the lockshields and the bleeding nipples as well, and give the system a chemical clean before draining. If you are fond of DIY and can do basic plumbing you can do all this yourself, but you need enough skill to do it without any leaks, and a few tools.

If you have to buy new valves, the Danfoss RAS-D2 (or C2, bit cheaper) is probably the best on the market. The Drayton TRV4 used to be the best, but is not quite as good. The Danfoss lockshield is also very small and neat, and high quality. Pegler Terrier is a high-quality brand but IMO not so stylish.

Thank you so much, that's really helpful. I am going to ask my friend to look at all my TRVs - there are at least 5 of them that don't work properly at the mo. The one that has entirely sheered off is British Gas, the other ones are random brands from what I can see

wow, people pay a lot of money for that kind of advice

Keeping your heating on constantly will not save you money - for one thing the thermostat will turn off the boiler when the temp rises above the temperature set, so the argument that it avoids firing up the boiler is nonsense.

However, turning the heating down to 16 degrees (from say 20?) will save you loads of money. The temperature in my house hasn't fallen below 17 degrees during the day yet this winter, so the heating would never be on.

The Energy Saving Trust agree with me! here via Moneysavingexpert

PigletJohn Just wanted to say a huge thank you for all the advice you've given on this thread. I actually understand what you've been saying!

We have a 3 storey house and a normal (non-combi) boiler that heats water when the heating is on - so we have to have the heating manually turned on and off as otherwise the water is too hot for the kids to use. We've set the boiler to the lowest setting and also the hot water tank to the lowest Summer setting but it still makes the water too hot to have the heating on all day.

It's a 10yr old house and we moved in last Autumn. We had the boiler serviced this summer and the plumber said he'd never seen a system like it () and couldn't advise on how to separate the water and the heating.

In the summer we can have just the water heated, but in the winter it's heating+water regardless.

Any thoughts?

"normal (non-combi) boiler that heats water when the heating is on"

this is typical of an old-fashioned system where the circulation from the boiler to the cylinder relies on gravity flow (hot water rising) and has no pump or valve. There is a thermostatic valve available to control that, but they are not often used now.

Over the last 20 years or so it has become the norm to circulate the flow to the cylinder by pump. The cylinder has a thermostat strapped to the side of it, through a cut-out in the insulation. This thermostat opens and shuts a motorised valve, and when the valve is open (because the cyl stat is calling for heat) it turns the pump on.

You say you have a cyl stat, so provided that it is adjusted and workling, it sounds to me as if there is no motorised valve in the primary flow to the cylinder; or, the valve is not working (either the motor has failed or the rubber ball in the valve is worn out). These are both quite common. I am stunned if you had a CH engineer in who didn't know how to fix it. Ask around for a better one.

Hi John, thanks. We have a pump attached to the hot water tank, is that what you mean? Sorry to sound dumb The boiler is a Potterton Suprima 70.

I'll show this thread to DH tonight and get him to call another heating engineer... it'd be great if we could have reasonable water temperature for once.

if it is a pump like this

then there OUGHT to be a motorised valve as well like this to shut off primary circulation from the boiler to the cylinder when the pump is not running.

Usually the same pump feeds both the cylinder and the radiators, and the thermostats from the cyl stat and the room stat operate a 3-port valve like this to send the supply one way, the other way, or both ways (the three port valve has one pipe coming in, and two going out, in a "T" shape)

I'm reviving this thread, but it may be of use to someone else...

When we moved into our present house, and living in Germany (so cold country, even here in the Saar valley) I was aware of horror stories on the internet: 'I had 3000 litres of oil and now, come Christmas it is gone and I don't have any money to buy new.' So I decided, as I didn't really know how much this house was going to 'use' in heating, to get thermostatic valves on the radiators, to keep the doors of individual rooms closed at all times (cold air wafting in from other places is what brings the temp down and so your radiator/boiler pops on) and to refrain from heating rooms which we do not use. I.e. bedroom gets heated in the evening, dining room gets heated just before we eat, library does not get heated as we are never there, kitchen not all day, only living room all day and I tend to keep it on in the morning at 18°. Radiators in the kitchen, bedroom, dining room are by default on 14°, living room on 18°. In the evening on 20-21°. Bathroom on 16°, but I think that is not really a room temp 16° as the radiator is too big for the room (same radiator as kitchen...).

Boiler goes off at 10 pm when we go to sleep during the week and at 10.30 on weekends (must change it at Christmas ). Comes on at 8.30 am as hubby finds he doesn't need it to leave for work (I work at home). Hot water comes on at 5.45 a.m. on hubby's working days, at 8.30 on other days.

Like this we saved about 2000 litres of oil in comparison with the last owner. Down to about 2300 l from 4500.

If I weren't here all day, i would definitely turn the heating off altogether (also turn it lower in the living room if we go away for the day). Nothing must be cheaper than 16°.

Oh, and airing is very important.

This stuff takes a lot of discipline, though.

I tried this last year and my bill ended up being double what it normally was.