Thermostatic radiator valves, or TRVs, work best when you set each one to the temperature you want in that room and then leave it alone. They aren’t on/off taps. Turning one up to maximum won’t heat a room faster, it just lets the room get hotter before the valve closes. Used well, TRVs let you keep bedrooms cooler and living rooms warm, which helps with winter bills. Our energy saving tips page has more ideas, and we look after heating systems in homes across Frome and Westbury.
What a TRV actually does
A TRV senses the air temperature around it. As the room warms up, a wax or liquid capsule inside the head expands and gradually closes the valve, cutting the flow of hot water into the radiator. As the room cools, it opens again.
That means each radiator can control its own room, while your boiler and room thermostat decide when the heating is on overall.
What the numbers mean
Most TRVs are marked from 0 or a frost symbol up to 5 or 6. Each number roughly matches a room temperature, but the exact figures vary between makers. As a rough guide on many valves:
- Frost symbol: stops the room getting cold enough to freeze
- 2: around 15 to 16°C, often fine for hallways and spare rooms
- 3: around 20°C, a common comfortable setting for living areas
- 4 to 5: warmer, sometimes 24°C or more
Suggested settings room by room
- Living room: 3 is a sensible starting point
- Bedrooms: 2 to 3, many people sleep better slightly cooler
- Hall and landing: 2
- Bathroom: 3 to 4 if you like a warm room after a shower
- Spare rooms you’re not using: frost setting or 1, with the door closed
Give each change a day or two before adjusting again.
The radiator that shouldn’t have a TRV
If you have a wall-mounted room thermostat, the radiator in that same room usually shouldn’t have a TRV, or should have it set fully open. Otherwise the TRV can shut the radiator off before the room thermostat is satisfied, and the boiler keeps running. Many systems also need at least one radiator without a TRV, or a bypass, so water always has somewhere to flow. Your engineer can confirm how yours is set up.
Getting the best from your TRVs
- Don’t cover them with curtains, sofas or furniture, as they’ll sense trapped warm air and close too early
- Close doors between rooms set at different temperatures
- Keep the room thermostat at a sensible level, often around 18 to 21°C, and let the TRVs fine-tune each room
- Bleed radiators that are cold at the top, so the valves can do their job properly
How to free a stuck TRV
After a summer with the heating off, the pin under the TRV head can stick, leaving a radiator cold. This is a safe check you can do yourself:
- Turn the TRV head to its maximum setting.
- Unscrew or unclip the head, following the maker’s design. The valve body stays on the radiator and no water should come out.
- You’ll see a small metal pin. Press it gently a few times with a flat object. It should spring back up.
- Refit the head and set it to the temperature you want.
If the pin won’t move, the valve is leaking or you’re not comfortable doing this, leave it for an engineer.
Older homes in Frome, Westbury and Trowbridge
Plenty of homes across West Wiltshire and the Somerset border are older terraces and stone cottages, some with radiators added over the years and a mix of old and new valves. Upgrading tired valves at the same time as other heating work in Trowbridge or Westbury can make a real difference to comfort. If you’re replacing a boiler, our boiler installations team can fit new TRVs at the same time.
Frequently asked questions
Should I turn my TRVs up to 5 to warm a room faster?
No. A TRV doesn’t change how fast the radiator heats up. It only sets the temperature at which the valve closes. Turning it to 5 just lets the room overheat and wastes energy. Set it to the temperature you want, such as 3 for a living room, and give it time.
Can I turn TRVs off completely in unused rooms?
You can set them to the frost setting, which keeps the room from getting dangerously cold while saving energy. Avoid leaving rooms completely unheated for long periods in winter, as cold rooms can attract condensation and mould, especially in older homes with solid walls.
Are smart TRVs worth it?
Smart TRVs let you schedule each room separately from an app, which can save energy if your rooms are used at different times. They work best with a compatible smart thermostat. They cost more than standard valves, so they suit households with irregular routines or rooms that sit empty most of the day.
Want your TRVs and heating checked?
Give us a call on 01225 708562 or drop us a message and we’ll check your valves and controls and help you set up your heating to suit each room.