Eliwell ELI 016 H6981 Cross Ambient Stat Thermostat Switch, Temperature Controller, Ambient Thermostat -5 to +25C, HVAC Control

Heating controls switch a central heating system on and off and hold rooms and hot water at the right temperature. This category covers room thermostats, programmers and time switches, programmable and smart thermostats, wireless thermostats with boiler receivers, smart radiator thermostats, motorised zone and diverter valves, valve actuators and wiring parts.

Types of control

• Programmers and time switches: set when the heating and hot water come on.
• Room thermostats: switch the heating off when the room reaches the set temperature. Programmable room thermostats combine time and temperature control in one unit.
• Wireless and smart controls: a wireless thermostat talks to a receiver wired at the boiler. Smart thermostats add app control, and some learn your routine and start the boiler at the right time to reach the set temperature.
• Motorised valves: on systems with a hot water cylinder, either one 3-port valve or a pair of 2-port valves directs heated water to the radiators, the cylinder or both. Match the pipe size and valve type when replacing one.

Regulations

In England, Approved Document L sets minimum controls when a gas or oil boiler is replaced: a programmer, a room thermostat, thermostatic control in each room (usually TRVs on every radiator except in the room with the main thermostat) and boiler interlock, so the boiler and pump switch off when nothing calls for heat. Systems with a cylinder also need separate hot water timing and a cylinder thermostat. A replacement gas combi boiler also needs one extra measure, such as weather or load compensation, flue gas heat recovery or a smart thermostat with automation and optimisation.

Mains wiring to controls and valves is electrical work, and some electrical work in homes is notifiable under Part P. For radiator valves, see thermostatic radiator valves, or browse radiators.