/ 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!