The heating controls in your central heating system are designed to allow you to control the temperature of your home and to use energy efficiently. For the controls to be effective you should be able to turn them on and off and they should rapidly react to any changes in room temperature. If you have thermostatic heating controls in each room they should provide varying levels of heat in different parts of your home, at levels set by you, and stop your boiler from working when it is not needed.

The main parts of your heating system are:-

Radiators enable the heat in the hot water generated by your boiler to be released into a room through convection of the surrounding air. So that the room is not too hot or too cold the radiator should be appropriate for the size of the room and if you have a new central heating system each room will need to be assessed. You should ‘bleed’ your radiator if you notice it is not as warm as it should be. Radiators also have valves to restrict the flow of hot water (see the section on valves and thermostatic valves below).

radiator valveRadiator Valves. Valves are provided in radiators to enable you to shut off or restrict the flow of water. This can be in an emergency following a water leak or when you wish to remove or replace the radiator. Turning the valve in a clockwise direction should close down the flow and turning anticlockwise will restore the water flow. If you plan to remove the radiator you should also close the valve on the other side of the radiator to completely seal it off prom the main plumbing.

Thermostatic radiator valves (TRVs). These act similar to radiator valves but they also control the temperature ofthermostat valve each room separately. To achieve this they sense the room temperature and reduce the flow of water into the radiator when it reaches the required temperature. They tend to work best in rooms which get too hot or are used infrequently. As they work independently of the main room thermostat you can achieve a more precise control of individual room temperatures and hence reduce energy consumption.

Programmers or time-clocks are the most useful controls for controlling the temperature programmer imageand energy usage. They can they turn your heating and hot water on and off depending on the times you set. More advanced programmers can have a different on / off pattern for weekdays and for the weekend. To be fully effective they should be capable of controlling the heating and hot water independently so that, say in the summer, you can still have hot water when the heating is off. Of course if you have a combi boiler then it produces hot water on demand so you need only be concerned about switching off the heating. Also look for the ability to advance a cycle and immediately turn on either the heating or the hot water without disturbing the programmed schedule.

Room thermostats automatically switch your heating off once the chosen temperature is reached and bring it back on if the temperature in the room falls. To save energy you should set thermostat imageyour room thermostat to the lowest comfortable temperature. In domestic properties this is usually 18°C – 21°C. It is surprising to learn that lowering a thermostat by just 1°C can cut up to 10 per cent off annual heating bills. A thermostat controls the temperature of the air in the room where it is positioned. They need a free flow of air to detect the ambient room temperature, so they must not be covered by curtains, blocked by furniture, or positioned near to drafts and direct sunlight or other sources of heat. You should also not put a thermostatic radiator valve on the radiator with the room thermostat or the operation of the two thermostats will interfere with each other producing unexpected effects.

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18 Responses to “Heating controls”

  • Lee says:

    What controls the hot water temperature when using a conventional boiler on the central heating system? the Hot water is too hot do you know what fault could be?

  • Boiler Systems says:

    Typically the water temperature is controlled by the boiler thermostat which can be adjusted by the customer.

    You mention that you have a conventional boiler system and this will have a hot water cylinder in the airing cupboard. Often these also have an immersion heated fitted (from previous use) and this also will have a thermostat. It is possible that this immersion heater has been switched on, heating the hot water.

    If you have a boiler service agreement you should contact the help line for assistance.

  • Ken Selvey says:


    I have a boiler insurance, I have lost the instructions to the thermostat controls. I have no heating now, could you tell me how to select the a temp of say 22 oC constantly on a thermostat please.

  • Boiler Systems says:

    The thermostat has two date ranges to program
    1 – 5 relating to weekdays
    6 – 7 relating to weekends

    To set a temperature

    Press the set button until the display shows three ‘stars’ with 1,2 and 3 in them and also a moon symbol at the bottom of the window
    Press yes
    Press yes again
    This will show you the start time for the program and the temperature
    To alter the temperature press the + and – buttons
    If you want to alter the time press the set button, the time will flash then use the + and – buttons
    Continue to press the set button to cycle through more time / temperature options and then return to the normal display.

  • Dennis says:

    I was told today that all radiators require by law to have thermostatic valves. Is that true?
    Also the gas feeder pipe to the boiler needs to be 22mm?
    Please advise.

  • Boiler Systems says:

    The gas supply to any new condensing boiler must be 22mm.

    While it is advisable to have thermostatic radiator valves fitted to radiators to improve energy efficiency its not a legal requirement.

  • michael mannion says:

    I have a baxi pt5 boiler but I cant work out how to set the timer. What make of timer is used with the boiler?

  • Boiler Systems says:

    There is not a ‘standard’ timer fitted to every baxi pt5 installation, the types of timer have varied over time. As such we are unable to help you unless you are able to provide any additional details.

  • Diane says:

    can gas boilers be put in upstairs bedroom airing cupboard with outside wall?
    can they be fitted in a bathroom that is upstairs?
    can a small radiator be fitted in a kitchen to a cupboard
    regards Diane

  • Boiler Systems says:

    1. Gas boilers can be put in upstairs bedroom airing cupboard with outside wall

    2. Gas boilers can be fitted in a bathroom that is upstairs. The boiler can be either vertically flued or if the bathroom contains an external wall, it can flue that way

    3. A small radiator can be fitted in a kitchen to a cupboard as long as the manufacturers of the cupboard state that the cupboard wall can withhold the weight of the specific radiator

  • Len Brown says:

    Is it O.K. to fit a combi boiler in a bathroom?

  • Boiler Systems says:

    Gas boilers can be fitted in a bathroom. The boiler can be either vertically flued or if the bathroom contains an external wall, it can flue that way

  • David Naylor says:

    I am thinking of changing my oil fired boiler to gas,the copper piping in my house is 40years old.
    1,Should the piping be replaced? (everything is ok at present)
    2,Space is not a problem,is a system boiler the right choice if the piping is not replaced ?

  • Boiler Systems says:

    1. As long as the piping is in a good state of repair then it should not need replacing but it will need to be chemically flushed.

    2. A system boiler would be the perfect choice for a straight replacement.

  • C.Brook says:

    Baxi Duo-tec Combi 28 HE

    Should the above boiler new have a separate room thermostat?
    I am being told that it is internal to the boiler.
    I cannot understand how it will respond to temperatures
    throughout the 3 storey house..

    Can you confirm that the above boiler does NOT need a
    separate room themostat and that it is contained within the actual boiler.

    Many thanks..C.B.

  • Boiler Systems says:

    Any thermostat within a boiler can only regulate the hot water temperature and not control a room temperature hence you need a separate room thermostat.

    The Baxi Duotec has the internal circuitry already installed to plug in an optional wireless receiver, so that it can receive temperature information from a separate wireless room thermostat.

  • C.Brook says:

    Thanks for confirming so quickly the information on my mothers new boiler.
    Now..on to mine..I have a Worcester Bosch Greenstar 24i junior.(installed 7 months ago.. My hand book covers 24i AND 28i. I cannot find a model number on the new boiler.

    It was connected up to the old thermostat point in the downstairs lobby. The face of the old thermostat being changed to a new identical thermostat.

    I work and relax upstairs most of the time. It gets far too hot. I know I can turn the rads down but sometimes I need instant heat quickly. I dont like fiddling with rads throughout the day/night.

    In a well insulated semi the upstairs stores heat and is a completely different temperature to the downstairs. Especially where the thermostat is situated. The heating is reluctant to switch itself off via this thermostat as its always cool there. Its also draughty despite new RIBA approved front external door. I contacted the installers and they said ..that I should get a decent letter box and therefore the thermostat problem was not their fault. I did get an expensive letter box
    is better but the problem remains.

    I work the heating now by running up and down the stairs to switch the heating on and off by the thermostat as its the best way to control it. I am 63 and wont be able to do this with much gusto soon.

    Do I have any re-call with the installer?

    or..Does this boiler have a wireless remote plug-in area
    inside the boiler which would allow a remote to be sited upstairs.?

    If a wireless remote is available, is it a huge expensive job changing over from the old hall stat. to one upstairs?

    Or you have any other advise on how I can get this system running more easily?

    Many thanks.

  • Boiler Systems says:

    The i junior range does have a plug in radio frequency thermostat but the issue with any room thermostat is that it only measures the temperature of the room that it is monitoring.

    If you house has large variances in temperature between the rooms it sounds that you need thermostats fitted to each radiator. Thermostatic Radiator Valves (TRV’s) can be fitted to your radiators and allow you to individually set the temperature for each room. This will save you money in the long run as rooms which are too hot are expensive to run, you have paid for the gas to heat them.

    To obtain a fixed price for this work, or to learn of the cost of installing a RF room thermostat please telephone npower or a local installer

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