Water is heated in a special chamber of the boiler which is usually powered by gas or fuel oil and is then distributed to different rooms of the home via radiators or other heat distribution systems installed.
Combi boiler room thermostat.
Thermostatic radiator valves in all rooms except the one with the room thermostat.
The table below shows a selection of standard and smart programmable thermostats from honeywell baxi ideal nest tado and drayon.
This is the same operation as the volt free system except in this case line voltage is applied to the controls and boiler.
The boiler only operates if both the programmer and thermostat are on.
A room thermostat preferably a timed or programmable one.
Traditionally the thermostat is connected to the boiler by wires running through the walls of the home.
Trvs are those nozzles located on the bottom of radiators usually with numbers 1 5 and an asterisk on them.
You can find out more about combination boilers and the best brands on our dedicated combi boilers page.
If the thermostat is also activated the sl terminal on the boiler is connected to line and the boiler operates.
This is called a single channel programmer.
A boiler interlock motorised valves.
The location of the thermostat is very important as the following examples show.
While your boiler thermostat and room thermostat are ways to control the temperature of your entire home and hot water thermostatic radiator valves trvs allow you to manage the temperature of individual rooms.
3 wire thermostat and programmer.
A programmable thermostat for a combi boiler need only control the heating as the hot water is instantaneous.
This activates the boiler.
A 2 wire thermostat is connected between line and the switched line terminal on the boiler.
A boiler thermostat helps in controlling the boiler operation thus maintaining a proper set temperature inside the home.
When heat is required the thermostat connects these two wires together applying the full mains voltage to the switched line terminal.