How user controls are linked to your heating system
Domestic heating accounts for 18% of the UK’s carbon emissions so knowing how your heating controls work can save you money and help fight climate change.
While upgrading heating controls to modern standards is the best way to avoid wasting fuel an understanding of your existing controls may also enable you to make savings.
Below is a brief guide to three types of heating systems and thier user controls in common use in the UK. It will help if you know your type of system i.e. fully pumped, gravity hot water, combi etc.
SYSTEM TYPE; Fully pumped
Diagram of a fully pumped system, with mid-position valve
click to enlarge
With a fully pumped system it is possible to have time and temperature control of both central heating and hot water although in some cases it may not be possible to have hot water independent of heating.
Until recently, it was common practice even with fully pumped systems, not to include a room thermostat but leave room temperature control to individual TRV’s. Adding a room thermostat will enable you to cap the whole house temperature. Modern standards require that such a thermostat be located in a room where the radiators are not fitted with TRV’s but adding a room thermostat to an existing system whether or not the room has radiators fitted with TRV’s will still be a useful addition to the system. One use for example would be to set it to a low temperature when the property is left empty during cold weather.
SYSTEM TYPE; Combination boiler
With a combination boiler hot water is heated instantaneously on demand, so here is little that can be done to save fuel here other than reducing the hot water thermostat temperature, something most combi owners are reluctant to do due to the slow delivery of hot water. Once again if not already fitted add TRV’s to radiators and a room thermostat.
SYSTEM TYPE; Gravity hot water, pumped central heating
Diagram of a gravity hot water pumped heating system,
click to enlarge
Many older systems are of the gravity hot water pumped central heating type. These systems are often fitted with just a programmer and a room thermostat. The programmer will not allow central heating only so whenever you have the heating on the hot water is also heated. If the room stat is satisfied i.e. the room in which it is located reaches temperature, it merely switches off the pump but the boiler will still fire and continue to heat the hot water up to the temperature at which the boiler thermostat is set. Even then the boiler will still fire from time to time (short cycle) as heat is lost from pipes, cylinder and boiler.
Without upgrading there’s little you can do to save energy with this type of control other than turning back the room thermostat and carefully setting the programmer timings or manually switching off. A minimum upgrade would be to add thermostatic control of the hot water by adding a zone valve and cylinder thermostat. Thermostatic radiator valves (TRV’s) could also be fitted. These will allow control of individual room temperatures.