Thermostats & Central Heating Controls | A Guide | Wireless | Digital | Room
Overview of Heating Controls
How to use this Guide
Thermostats and Controls by Type
Room thermostats – digital or dial
At their most basic, heating controls tell the boiler to come on and go off. Their main component is a room thermostat. You set the room thermostat to your desired temperature and it will tell the boiler to come on until that room temperature is reached. Once reached, the thermostat will tell the boiler to go off again. These take the form of a digital thermostat reading or a dial thermostat.
This is a very simple system and can mean the boiler comes on an off all day to meet the room temperature unless you manually turn the temperature down. It can be fitted by your boiler installer.
Wireless thermostats use an infa-red connection to the boiler to control when it comes on and offer. These are used when it is difficult to run a wire from the boiler to the thermostat.
Wifi thermostats are another way of referring to ‘smart thermostats’, where by the thermostat is connected to your internet. It is then possible to control your heating system from a smart phone (see below for more on smart controls).
Central heating programmer and ‘seven-day’ programmable thermostat
In order to automate the times at which the boiler comes on and off, for example if you only want your boiler to come on in the mornings and before you get home from work, then you will need a central heating programmer. A standard central heating programmer (or programmable thermostat) will allow you to set the boiler to come on at the same times each day, for example, from 6am – 8am and 5pm until 9pm. If you want to set different times on different days, you will need what is called a ‘seven-day’ programmable thermostat. All programmable thermostats are digital.
When a heating system can be controlled in this way it is much more efficient. Almost all boilers are compatible with programmable thermostats and they can be fitted by your boiler installer. They are cost effective to install and will save you money.
Boiler timer or Central heating timer
A boiler timer, often referred to as a ttime clock', is budget option to set times for the boiler to come on and off. It is a dial fixed to the front of the boiler with little ‘pins’ that you push in to set the times for the boiler to operate. These still work with a room thermostat. Time clocks only work with combi boilers where there is no need for separate hot water controls.
Separate Hot Water Controls
‘Twin channel programmers’ are used where you have a hot water cylinder and you wish to programme hot water times as well. Twin channel means there is a ‘channel’ to control the heating AND hot water separately.
Smart Thermostats and Smart Heating Controls
Smart heating controls (often referred to as Smart Thermostats) allow you to control your temperature from your phone, although many offer other features. Their levels of sophistication vary from a simple programmer controlling the heating or heating and hot water, to complex systems controlling two or more zones that can incorporate smart valves, multiple thermostats and hot water timing and temperature controls.
For most of us, a standard product such as the Nest or one of the boiler manufacturer’s own smart controls is all that is needed. These can be fitted by your installer as part of a new boiler installation or in the case of Nest by a Nest engineer.
For more on smart controls and boiler compatibility read our comparison guidance: Nest & Hive Verses Boiler Manufacturer Controls
Heating System Controls
In addition to controlling your boiler, it is possible to create a more efficient heating system by better controlling your radiators. This can be achieved by ‘zoning’, Thermostatic Radiator Valves (TRVs) or Smart Radiator Valves.
Conventional zoning is really only worth undertaking in larger properties. It involves piping two heating zones, usually ground floor and first floor. Each zone is controlled by a separate thermostat, allowing you to set different temperatures on each floor thus saving energy. For example, 21 degrees downstairs and 16 degree upstairs.
If you are extending your property significantly, you may wish to consider separating the ground and first floor radiators in this way. It will involve re-plumbing parts of the system and additional pipework, as well as adding zone valves to each circuit.
Thermostatic Radiator Valves
For smaller properties, the work and cost involved in re-piping the system to create two zones is rarely worth it. There are more cost effective, and less disruptive, ways of achieving variations in temperature.
The conventional way is to fit Thermostat Radiator Valves (TRVs). This will allow you to control the temperature of each radiator, e.g. turning off radiators in little used rooms and turning them down in the bedrooms. This is a manual exercise but once done rarely needs changing. TRVs can be fitted to most radiators by a plumber. For a comprehensive review of 32 TRVs regard our Guide to Thermostatic Radiator Valves.
Smart Radiator Valves
Smart radiator valves will also individually control heat radiator, the difference is that the temperature can be controlled by a central programmable room stat. Smart valves can be grouped together to operate as a single circuit or controlled individually. They are a very easy fit to most radiators.
Smart radiator valves are compatible with Honeywell Evohome, Heat Genius, Nest and Netamo smart controls – for more detail read our Guide to Smart Thermostats.
You may hear heating engineers talking about ‘twin channel programmers’; One and seven day programmers; and weather compensation etc. What does all that mean? They are describing the different types of control that go with different types of boiler system:
Single Channel and Twin Channel Programmers
A ‘channel’, like a radio channel, is the means by which the thermostat communicates with the systems it controls.
A programmable room stat will have commonly have one (single) or two (twin) channels, although some have three. The first channel will control the boiler. The second channel will control the hot water.
Single channel programmers
These are used with combi boilers, as it is not necessary to control the hot water separately (this is done by the boiler).
Twin channel programmers
These are used with regular and system boilers where the programmer needs to control the heating and the hot water timing. (They can also be used with combi boilers where there are two separate heating circuits or a mix of radiators and underfloor heating).
Three channel programmers
These work with regular and system boilers to control two separate heating circuits plus the hot water. These are only used in larger properties where the ground and first floors are separately piped to create two radiator circuits (called zones) or where there is a mix of radiators and underfloor heating.
‘Weather compensation’ is a way of helping the boiler to operate more efficiently. It is often included as standard with modern programmable room stats and smart heating controls.
It traditionally involved a temperature sensor on the outside of a property linked to the internal programmer/thermostat. The sensor is able to forewarn the boiler of a change in outside air temperature which will eventually lead to a decrease or increase of inside temperature. The boiler can respond by increasing or reducing its output slowly to meet the predicted change in internal temperature. This leads to less ‘cycling’ (the boiler coming on and off) and more efficient periods of operation.
Most weather compensation systems have moved away from an outside temperature sensor (although it is arguable more accurate) to using data from the local weather station to inform your heating system of a change in temperature. This ultimately makes for a more straightforward installation with fewer parts to go wrong.
Finally a quick explanation on cylinder stats, since they are a form of control. Cylinder stats are fitted to all hot water cylinders and control the temperature of the hot water – they are usually adjusted via a little dial.