Radiator Controls

Generally, one radiator should be left without a TRV and left permanently switched on, unless the boiler is fitted with a flow meter to detect when all the radiator valves are closed. This special radiator may be a bathroom towel rail (where the heat is always likely to be useful), or in the same room as the room thermostat. It is not a good idea to have a TRV on the radiator in the same room as the main thermostat, as if it turns the radiator off at a lower temperature, it can mislead the main thermostat into thinking that the house is cooler than it really is. When fitting TRVs, it should be noted that some are bi-directional (can be fitted on either end of a radiator), but many are best fitted at one end only (either flow or return) to reduce the chance of noise in the system.