/ Home & Energy

Tricky thermostats – is your central heating out of control?

Some tiny plumbers fixing a radiator thermostat

Keeping our homes warm during those chilly winter months is essential to most of us, but are you spending more money on heating than you need to? Are you in control of your thermostat?

In our recent heating survey we found that around two thirds of people with central heating have a timer to turn the heating on or off. But only half have thermostatic valves on at least some of their radiators. And less than half have individual room thermostats.

To get the best out of your heating system and save money, each house should ideally have a full set of controls:

  • A timer or programmer to set when your boiler should turn on and off.
  • A room thermostat to set the temperature you want your heating to achieve.
  • And thermostatic radiator valves to control radiators in each rooms.

The Energy Saving Trust estimates that you could save £70 per year on average if you were to install a room thermostat (in a typical three-bedroom semi-detached home heated by gas).

A flexible approach to heating

As David W put it in a previous Conversation about heating:

‘What one really needs is a device that compares the ambient temperature with a pre-set ideal and switches on the heating if (and only if) it’s needed, summer or winter. Because if it’s cold, it’s cold, whether it’s August or December.’

A letter we received from Mike Astill suggested the use of portable wireless thermostats. He moves the thermostat from living room to bedroom etc as he moves around the house. He also turns down the radiator valves in the rooms he’s not occupying.

Confusion over complex controls

But even if you have a heating timer, do you know how to use it? Some are quite complex and not at all intuitive. One in five people who have a timer and don’t use it, say it’s because the timer is too complex to use or they don’t know how to use it.

When first installed, your heating engineer should explain how to use the timer and the thermostat, but do they? In detail? And what about if you move into a house that already has a timer, but the previous owner has not left any instructions for the boiler or controls? How do you find out how to use them?

Our research also found that almost one in 10 people who don’t use a timer for their heating say it’s because they believe it’s more efficient to leave the central heating on all the time.

Do you have a full set of heating controls in your home? And do you know how to use the timer? Do you have any tips on how to make the best use of heating controls to save money while still being comfortable in your home?

David Bunting says:
18 March 2013

I have just installed an Inspire Automation Internet thermostat. It is brilliant. I can now control my central heating from anywhere in the world, with my smart phone, and check the current temperature of the house. This is important to me as we are often are away during the winter.

This should save me a lot of money as Iwill not need to leave the heating on unnecessarily.

I now use my phone or netbook to control the heating even in the house, as it saves me having to go to the boiler room.

David Knowles says:
19 March 2013

Re Portable Thermostats – Mike Astill wrote in the March issue that he uses radiator stats and a portable stat. Surely the idea of radiator stats is to set them at your required temperature. Buying a portable stat is surely pointless as one will cancel the other out.
I have a thermostat in the coldest part of the house and then regulate each room with radiator stats, if a room is a little cold I can simply adjust the stat on the radiator without affecting other rooms in the house.


The problem with thermostatic radiator valves (TRVs) is that they are a very crude way of controlling temperature because they are next to the radiator. No sane person would put a room thermostat next to a source of heat. I am not saying that TRVs are useless, since they are better than simple control valves, but proper room thermostats sited in sensible places are very much better.

Wireless portable thermostats are very convenient and can easily accommodate changes in how we use our houses. Unfortunately they can sometimes be affected by interference by other household items.

Laurie says:
18 November 2013

As I understand thermostatic radiator valves, they do not respond to the ambient temperature of the room as you might feel it sitting several feet away from the radiator, but to the temperature of their immediate vicinity. This is going to be a mixture of warm air next to the radiator when it’s operating and cooler air near the floor (unless the valve is at the top of the radiator), as warm air rises and cool air sinks. The heat put out by the radiator will affect the valve, but only partly. However, one is warned to ensure that the valves are not covered (e.g. by curtains) — in that case the air won’t circulate around them.

Jeggers says:
8 April 2013

I have been using Househeat wireless thermostats in conjunction with radio controlled motorised radiator valves. The thermostats are programmable with on and off times. We use one in the bedroom which is set to come on later in the day than the heating in the rest of the house. Another is installed in the main living area and only comes on in the evening.

As well as controlling the radiator valve(s) in the room where the thermostat is located, it can also control the boiler or central heating pump so that the boiler only comes on if one or more of the thermostats tell it to. All this is done wirelessly and everything is battery powered. Battery life is at least 1 year (this is al long as I’ve been testing the product).

The system is expensive, but does seem to provide excellent flexibility. I’d be interested to hear anyone else’s feedback on using this product.

Laurie says:
18 November 2013

This sounds very much like the system in our old house, the name of which I couldn’t remember. We found it difficult to program at first, but had the heating engineer set it to our specifications, and then were very happy with the way it operated — in six years we never touched it except to change the batteries or change it from “holiday” to “regular” settings.

Simon Young says:
9 April 2013

We have had a Drayton Digistat RF3 installed since the heating was put in over 9 years ago. Initial problems surfaced quite soon, when the unit kept cutting out. This turned out the be the battery trays not seating properly and breaking the connection. A rubber band and a couple of matches soon fixed that problem, and since then it has worked faultlessly, with a very long battery life. Programming the ‘stat was a bit complex at first, but after a few goes, became intuitive, quick and easy. It gives three time zones so early morning, during the day and evening temperatures can be set separately. There is also a separate programme for Saturdays and Sundays. There are 3 mode settings, on permanently, timed and standby. Ours is located in the hall and set at 17 deg. C all day and 7 degC at night. We very seldom move the unit as the radiators have thermostatic valves, so unused bedrooms are turned down at the valves. The most significant energy saving strategy we have found is keeping all the doors to all the rooms closed at all times. This way, the hall maintains a very comfortable background temperature, while the kitchen, dining room and sitting room are warm enough to sit and relax in. Altogether we are very satisfied with the unit.

Laurie says:
18 November 2013

We’ve recently moved. Our “old” house had a combi condensing boiler, a wireless (but not portable) thermostat that allowed three levels of setting (typically night-time and two others) of the temperature. Then every radiator but one had a thermostatic radiator valve. We were very happy with this system and it seemed very thrifty as we’d turn down the thermostatic radiator valves in rooms we didn’t use often and shut the doors.

Our “new” house, on the other hand, has a condensing boiler with a separate pressurised hot-water system. The towel rails in the bathrooms are linked to the hot water system, while the other room radiators are not; thus they get warm when the boiler heats up the water twice a day. There is a timer that has separate controls for the hot water and the central heating and allows overrides (e.g. times, once on, always on, always off). We have a room thermostat and every single radiator (including the towel rails) has a thermostatic radiator valve. The radiator valves, regardless of what they appear to be, seem to behave as either fully-on or fully-off. Thus a room can get very cold, then quite quickly far too warm, then cool down to cold again before the radiator functions.

It seems to us that the separate controls spend much of their time overriding each other and nothing we do seems to achieve our goal, which is a fairly even heating all the time, being able to set this as cooler at night and warmer during the day (we are retired and almost always at home). A local builder has suggested that the room thermostat is possibly in the wrong place, a large-ish open-plan room. We’d really like to stop having to fiddle constantly with the various controls but short of having a heating engineer who understands heating system design come and have a look and make recommendations, I don’t know what we can do. As the house is extremely well insulated (walls, under-floor and roof space) it shouldn’t be so difficult to maintain an even temperature, and to set that by room and by time. Any suggestions gratefully received!

Malcolm Duke says:
18 November 2013

You don’t say if you’re happy with the hot water/towel radiator arrangement.

To set up your central heating I would suggest the following:

Have the central heating timer ‘on’ for longer periods
Set the main room thermostat at a moderate temperature ( ie 18-20 degrees C)
Set all the thermostatic radiator valves at 50%.

Over a few days, tweak each TRV (turn down a notch if too hot, up a notch if too cold) until you are happy with the relative temperatures. Then adjust the room thermostat and/or timer.
Hope I’m not teaching anybody to suck eggs, but that’s what I’d do.

Crazy or what? says:
22 October 2014

What I need is a list of top 10 thermostatic heating controls!!! I need to replace but can’t find any info on this site. Crazy or What?

Simon Young says:
22 October 2014

Hi Crazy. I refere you to the comment I made on the 9th April 2013 about the Digistat. Since then, no problems have arisen, and we have not had to change the batteries. I would put this unit into the top ten. Best of luck.

peter stringer says:
11 November 2014

Hi I have just posted an comment which might help you.

Jeggers says:
22 October 2014

I have been using Househeat motorised TRVs in our living room and bedroom with wireless thermostat in each of these rooms. The stats control the TRVs and also the boiler so that the boiler is only on when one of the TRVs is open (ans therefore calling for heat).

All the other rooms have manually operated TRVs, which we have adjusted over time by trial and error to maintain comfortable temperatures in these rooms. We work from home, so leave the main boiler control set to have the heating on all day. Each wireless thermostat is programmable, so we have the bedroom one set to come on for a couple of houes night and morning and the living room one in the day/evening.

The Househeat system has been in for a couple of years now and perfrorms well. I have replaced the batteries once since installation.

The system is expensive, but does provide great flexibility.

peter stringer says:
11 November 2014

Hi I was considering this system but the price of the boiler controller put me off. i am sure i saw a similar controller last year on ebay brand new for about £180 but alas i cannot find it.my system cost me about £320 for a two bed two reception flat with en suite and shower room.

peter stringer says:
11 November 2014

I have been using wirelessly controlled motorized valves on the bases or the original trv’s they are made by a german company eQ-3 Maxi they link to wireless room thermostats and a hub which enables control via the web if required.the valves can be programmed for on and off times either centrally via the hub or manually. The room temperature can also be programmed. The only draw back of the system is that it does not communicate demand directly to the boiler. i have seen a system that does but the price is ludicrous. So my system enables me to program the time and the temperature in each room . I can override using a boost or comfort button and put the system into manual mode at any time My house is upside down with the bedroom in the basement So I can now switch on the downstairs radiators 25mins before the upstairs . i can then switch them off all programmed. I also have an eco switch that I press as i go out the door to go out or on holiday. the cost is about £50 a room plus £50 for the hub .In rooms that we use at set times i have simple motorized valves costing £10.oo each from the same firm eg the bathroom and the shower room I tried cutting costs by not buying the wall thermostats but found that they gave a much more accurate result allowing for the boiler in my office and cooking in the kitchen. as well as getting over the localized heating which radiator thermostats are subject to. Unfortunately I am still a slave to the boiler thermostat and time clock but if I was braver I would leave the boiler on continuous and let the system do its work.
No room in my house is heated unnecessarily at any time. if i wished I could buy window controllers that shut the rads off when I open the windows or a wirelessly controlled switch to shut of the immersion heater.I am waiting for us to have two winters the same to be able to assess the savings

Rachel says:
8 December 2014

Hi my heating comes on to the rimes I have set on the timer unit. Recently it comes on but after 15 mins or so the heating all cuts out and the timer unit display is all blank shut off completely and I have to switch it off at the fuse box and put it on again for it to start up again, then it stays on. Any ideas where this electrical fault could be??

It sounds to be a timer fault put the timer on manually to see if it stays on then a new timer or an electrician to check depending on the type of timer it should not cost too much for a new one get one from where you can return it if that does not work B&Q are happy for you to return anything for one store there are other too

hi i have a combi boiler my central heating thermostat is in the hall i only have thermostatic valves fitted in lounge and conservatory. problem i get is heat in conservatory is 4 degrees lower than in hall how can i compensate for this do i need wireless thermostat

Insulation ! your conservatory has glass all round ? double glazed glass helps to insulate

Dilemma. In my last house there were 8 zones (radiators), each controlled by an Evohome motorised TRV associated with a wireless controller. Those rooms not used were kept at 15 C, day and night. Used rooms were set for an individual time and temperature program. When all TRVs were satisfied, the controller turned off the boiler, meaning that while heat was available 24 hrs/day, it was only on when necessary. This converted an old cold house into a comfortable one.

I have recently moved and would like to use the same system, however, there are 19 radiators and the cost of doing so would be considerable. The existing radiators have modern normal TRVs. Is there any way of mixing these with the Evohome system? The problem being that the programable TRVs may turn off the boiler when the others were still requiring input. Or the boiler pump would need to run 24hrs/day.

Is there any practical way of achieving the situation in house 1 without using 19 programable TRVs in house 2?

Michael Crick.

I’m not sure of the purpose of keeping unused rooms at 15°C. Unless there is a problem with dampness it seems like a waste of energy.

15 degrees for an empty room ? I am warm enough with my controller/thermostat set at 16 degrees I do not want being cooked every day Some people got used to living in over-heated houses when energy was ” cheap “and still now do the same then complain about their energy bills are but will not lower the temperatures even 1 degree

Me too 🙂

A motorised valve stopping hot water reaching different parts of the system maybe closing off several radiators together might work Consult an heating engineer he will advise and hope any work will go his way

We have just had a quote from British Gas to fit 11 radiator valves in our property. We still have an old boiler which we will have to change in the not too distant future. We were quoted £670.00 to supply and fit the valves , we have not idea if this is reasonable or not. We would be pleased to receive any comments.

I’d ask a local plumber to quote – maybe two. See if you can find them by recommendation or through Which?’s Trusted Trader scheme

I would suggest waiting until you have the boiler replaced because it is likely to be more cost effective to do both jobs at the same time. That does seem a lot to have the radiator valves changed, which is usually straightforward. It’s always worth getting more than one quotation, as Malcolm has suggested. I had work done on my roof last year and the small company recommended by a friend who is a buildings expert was substantially cheaper than a local builder, and I’m happy with the work.

If the boiler is on its last legs or if parts are no longer available it would make sense to change it. If you are planning to have it replaced because a new one is more efficient then that might be false economy because it could take a long time to recoup the costs in saved gas costs. Modern boilers are not always as reliable as older models and the last service engineer to look at my 18 year old boiler strongly advised me to keep it for this reason.

Given the costs of all those TV adverts, I would not be surprised if a good local heating company were less expensive than British Gas.

The price that many could easily do themselves Drain the system a spanner to undo them to put the new ones on refill with wit water the job is done for little more than the cost of the valves get your local handy man to do it a plumber is not need for such a simple task

no surprise they will be although plumbers can charge the earth I should have been a plumber not the idiot I now am

Replacing radiator valves is not a difficult DIY task and the valves are readily accessible, which is often not the case with plumbing work.

Two heating issues:
1. We had a new Worcester combi boiler installed some 3/4 yrs ago now – just during this last winter season it has started to be very noisy in the radiators which are switched on – never had this before over the 30 yrs with old or new boiler. It drives me mad.
2. Having had radiator valves fitted to 6 of the 8 radiators 30 yrs ago, increasingly we are finding one of the radiators, whose valve is switched off, becomes warm when heating first comes on in the morning. I then have to turn it up to max and off again, before it will go off completely. It’s happened intermittently with three of them now. Is it likely old age? Do we need to replace the valves?
Grateful for guidance

Hi Su,

I’m not a craft trained plumber, but my thoughts are:

For item 1, I’d look to see if the radiators need bleeding, i.e. to remove any trapped air that may be in them. (I’d also check the pressure gauge on your boiler, e.g. to check that the needle is in the green sector of the dial, if it uses a dial gauge – my 8 year old one does. If the water pressure is too low, you may need to top up the central heating water circuit.)

For item 2, I’ve worked in offices where old thermostat radiator valves no longer worked properly, so I guess some of your 30 year old values might be due for replacement,

This comment was removed at the request of the user

Su refers to radiator valves having been fitted to some of the radiators. I assume that these are thermostatic radiator valves. These can be troublesome and it’s probably worth replacing them after this length of time. The plumber will be able to check for other problems such as internal corrosion of radiators due to lack of corrosion protection in the system. When the boiler was replaced the system should be flushed and corrosion inhibitor added, and nowadays it’s common to add a magnetic trap to collect iron oxide corrosion products, but not everyone does a proper job.

Sue, is the noise like a loud snick that stops when the radiators have heated up? We have one that does that and I think I am to blame keep knocking into the radiator with my chair.

We have a thermostatic valve that seems to trap air. The thermostat is turned down to 3, gurgles away and turning it up and down again, clears it. We recently had a thermostatic valve changed and the air is working its way out of the system. We also have air relief valves in our loft that look like pipes sticking up with a release valve on the end of them.

If one of our radiators is turned off, hot water in the pipes still gets as far as the thermostatic valve that might be why it is warming up.

Your valves sound as if they still work but if ours get stuck removing the top and working some silicon into the spindle can make them last a bit longer. You need to search for your valve to find out how to get into it.

One thought, if air is getting into the system and causing the noise, do you have a leak somewhere? Bleeding the radiators is a good place to start.

You are doing very well with 30 year old radiator valves, we seem to have one or two replaced every year, they just don’t make like them like they used to and I know of some that are 40 years old and still working.