Fitting thermostatic radiator valves (TRVs)

Last updated Wednesday 30 April 2008

Keep your cool with heat control in every room

Get a comfortable temperature right through the house by fitting thermostatic valves to your radiators. They work by sensing the air temperature in the room and adjusting the heat accordingly, saving money and cutting CO2 emissions.

Most of us have a central heating system controlled by an electronic thermostat, but by fitting thermostatic valves to each individual radiator too you can vary the temperature according to the room - so you don't need to be heating the whole house just to get the living room warm.

For the average home, you can save around 90kg of CO2 - that saves about as much CO2 as switching your gadgets off standby - and around 10 a year.

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Photo: Fitting thermostatic radiator valves (TRVs)

Saves 90kg of CO2 a year

470 Bloomers are doing this

CO2 reduction 1 out of 5

Cheapness 3 out of 5

Popularity 4 out of 5

Cost 56 per house

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How does it work?

Pub Fact

  • Turning a TRV to a higher setting will not make the room heat up any faster. How quickly it heats up depends on the boiler size and setting, and the radiator size.
  • In a recent Building Research Establishment study, many people admitted to opening windows to cool down their home if it overheated.

Thermostatic radiator valves (TRVs) contain - as the name suggests - a valve that determines the hot water flow into your radiator. Usually a wax plug linked to the valve expands or contracts according to changes in room temperature and controls the valve via a connecting pin.

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How will it make a difference?

In Britain, keeping our homes warm accounts for around 20% of the CO2 that we can directly control. Having inappropriate heating controls, or using them incorrectly, means your central heating system works unnecessary overtime and could be adding 17% on top of your energy bill each year.

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What's stopping me?

"I already have a thermostat on the wall. Won't they work against each other?"

Yes, but only if they're in the same room. Your wall-mounted thermostat is very commonly in the hall, so you shouldn't have TRVs there. If you do, the radiator's thermostat will shut the radiator off when the temperature is reached, only for the wall thermostat to fire up the boiler and compensate for the cool radiator. And so on, and so on. End result: your boiler takes a hammering and the room stays cold.

But otherwise the two systems work very effectively together. The wall thermostat determines the maximum temperature for the house and the radiator valves let you vary that limit room by room - people generally don't want their bedroom as warm as their living room, for example.

It also means you don't have to waste money and energy warming rooms you seldom use just so you can be comfortable in the ones you do.

One thing to note: if you turn a TRV down low in one room, keep the door to that room closed. Otherwise the radiators in adjacent areas will just work overtime to heat the air in there too.

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How do I do it?

  • Decide whether to DIY or GSI (get someone in). But apparently it's easier than it sounds
  • DIY will cost you 8 per valve - (around 56 for the whole house) add around 100 if you're getting a plumber to fit them. This should pay back in between five and ten years.
  • To find an accredited plumber contact The Institute of Plumbing and Heating Engineering
  • Put them on each radiator, but not in the living room or the room with the thermostat dial
  • They don't work like a dimmer switch! TRVs are most effective if kept at a constant level
  • Heat the rooms you use most, rather than the whole house. Carbon consultant Chris Goodall recommends setting your thermostat to 18C and keeping half the house (possibly the upstairs if that's where your bedrooms are) about three degrees lower than the main living rooms. Or you could simply try turning off radiators in bedrooms
  • Don't cover radiators with curtains or block them with nearby furniture or they may not work properly

Further details on DIY installation

  • Get advice from your local DIY shop to find out what is compatible with your heating system
  • Ensure you follow the instructions supplied with your TRVs
  • It will take about an hour to change each valve
  • You will need tools including: plumbers tape (PTFE tape), two plumber's spanners, a bowl to catch water drips and a radiator Allen key

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When should I do it?

The autumn is an ideal time, just before your heating system fires up again for the winter.

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References

  • Goodall: How to live a Low Carbon Life
  • Energy Saving Trust: Heating controls leaflet
  • DIYnot.com
  • Kathryn Rathouse and Bruce Young: Use of domestic heating controls

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Comments

hot chile one, Westcliff-On-Sea 2009-02-21

When A category condenser fitted in December 2008, British gas fitted them in the cost of the new boiler. Works a treat and keeps the rooms not in use down low.

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Glossary terms used on this page
CO2
CO2, or carbon dioxide, is made up of the elements carbon and oxygen. It exists quite naturally in our atmosphere, as part of the carbon cycle. Everyday processes in the plant and animal world both add CO2 to the atmosphere and take it out. However, because it is a greenhouse gas - meaning it affects the temperature of the earth - the exact level of CO2 is important. Burning fossil fuels releases CO2 into the atmosphere, hence the anxiety that extensive use of these fuels is causing climate change.
Carbon
Carbon is the fourth most common chemical element in the universe, and carbon compounds - in other words, carbon chemically combined with other elements - are the basis of all known life forms on earth. Pure carbon appears in many apparently diverse forms, from diamond to graphite to charcoal, but it is much more commonly found in substances such as coal, oil, natural gas, wood and peat that we use for fuel. When we burn these substances to provide energy - either directly in our homes as heat, or in power stations to produce electricity - the combustion process produces 'oxides' of carbon, including the gas CO2.
Thermostat
A thermostat maintains the temperature of a system at or near a stipulated level using sensors that tell it when to turn off heating devices. In most household central heating systems, a wall-mounted thermostat is used to set a maximum temperature for the house, while thermostatic radiator valves can be used to set a desired level for individual radiators.
Thermostatic radiator valves
Thermostatic radiator valves (TRVs) automatically open and close as necessary to control the flow of hot water into a radiator and so achieve the pre-set air temperature for a particular room, rather than for the whole house. The level is set by turning a dial on the radiator.

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