Basic efficiency using thermostats and TRVs

Basic efficiency using thermostats and TRVs#

The most basic, and oldest, energy efficiency requirement is to have a way of controlling the heating in individual rooms. In most of our buildings, installers have met the requirement when the boiler was installed by putting thermostatic radiator valves (TRVs) in most rooms, with a room thermostat and no TRVs in one room per heating zone. The TRVs control the flow of hot water through the radiator by opening and closing a valve. The room thermostat controls the boiler, turning it on and off. The ideal is workable individual room control in as many rooms as possible for your system.

Explanation of TRV benefits - from BEAMA

Keep enough radiators uncontrolled

It can damage your system if your boiler and pump try to circulate hot water without enough places for it to go. This can happen if you have TRVs everywhere and they are all closed at once. This is one reason for the room thermostat. Because it controls the boiler directly, the radiators in the room with the room thermostat are always open. If those radiators don’t have enough capacity for your system, or if you don’t have a room thermostat anywhere, you might have other uncontrolled radiators, for instance, in your hallways or toilets. You shouldn’t add more TRVs without knowing how many radiators need to be left open as a “bypass” for the system. What you need depends on the boiler, pump, pipework, and system configuration, such as whether you have an automatic bypass valve.

Old-style TRVs rely on people operating them manually. This strategy takes more cooperation from building users than most organisations can obtain. Your group can consider internet controls instead. With internet controls, you replace thermostats and TRV heads with new ones that give you better control without having to be on the premises.

Internet controls

If you stick with manual operation, you should:

Replace any analogue room thermostats with digital ones. They are more accurate and make users more comfortable by keeping the temperature from varying too much, so they will often allow you to set the temperature a little lower.
Ensure that your TRVs aren’t missing the heads. If they are, users can’t use the dials to control them. The heads are easily replaceable.
Check that your thermostats and TRVs still work. TRVs can only be replaced by draining the relevant part of the system, which can be expensive if you don’t have another reason to do this. Modern TRVs work better than old ones so if you are draining the system and intend to keep it for a while, you might consider replacing any worn TRVs at the same time.
- Do thermostats work and are they effective?
Consider whether you can add limiting pins to your thermostats and TRVs. This keeps groups from turning thermostats and TRVs all the way up or all the way down in a misguided attempt to heat or cool the room faster and then leaving them that way. Using limiting pins makes it more likely that the next group will be able to make themselves comfortable and will reduce your energy costs by reducing overheating. Otherwise you can think about other ways of imposing restrictions, but don’t make groups so uncomfortable they sneak in space heaters or use fire extinguishers to block doors open.