How to Fit Radiator Valves


Fitting new radiator valves to replace ones which are old, jammed or leaking is a fairly straightforward plumbing job. However, you can use the same techniques to replace conventional valves with thermostatically controlled models (TRVs), so that the heat output of your central heating system is controlled on a room-by-room basis instead of relying on a single room thermostat.


Is it worth it?

Although TRVs can save on fuel bills by keeping individual rooms at a preset temperature, whether or not this justifies their cost depends on the rooms themselves and also on how the valves are used.

South-facing rooms which are warmed naturally by the sun, and spare bedrooms requiring only background heating, are two ideal locations. Most TRVs also include a frost setting for keeping the heating ticking over if the house is left empty during the winter.

On the other hand, living rooms which need a good level of heat all the time the central heating is running are unlikely to benefit much from TRV control unless there’s a fire as well. And in any case you must leave at least one radiator open on a manual valve so that the pump doesn’t meet undue resistance every time the heating switches on.

Whatever the room, the amount of fuel saved ultimately depends on people’s willingness to keep the thermostats turned down — TRVs left on maximum setting all the time will save nothing.


Shopping List:

Replacement valves and TRVs (see below) are widely available from DIY stores and plumbers merchants. They are generally sold complete with a new compression ring (olive), valve tail and coupling nuts, so the only other material you need is PTFE tape for sealing the valve tail threads.

The only special tool required is a hexagonal Allen key for shifting the old valve tail — ask at your plumbers merchant. A hot air stripper may also come in handy to make releasing the joints easier.



Manual valves fall into two categories: handwheel and lockshield.

Handwheel valves are for turning the radiator on and off, and are usually (though not always) fitted on the flow side.

types of radiator valve

Lockshield valves keep the flow through the radiator balanced and should be left undisturbed once set.

Most types work on the spindle principle, like stopcocks. However, a few more expensive models use expandable bellows instead of O ring seals, giving improved performance. Valves with built-in drain cocks are also available.

Thermostatic valves (TRVs) are fitted on the flow side of the radiator. A correctly set valve balances the flow automatically, so the lockshield valve on the other side of the radiator becomes redundant and can be left fully opened.

TRVs work by having a gas or liquid sealed in the sensor head which expands as the temperature rises, pushing a plunger on to a spring loaded spindle in the body to close the valve. There are numerous models to choose from, but look for the following features when buying:

typical TRV

♦ Easily replaceable spindle ‘O’ ring seals. These get a lot of wear, so it’s helpful to be able to renew them without draining down the system. All types have replaceable sensors.

♦ Remote sensors. These are an option on some valves, and give more accurate readings where the air flow around the valve is restricted by such things as furniture or long curtains.

♦ Matching inlet and outlet fittings, allowing a choice of vertical or horizonal mounting on either side of the radiator. This could be important if space around the valves is restricted.

♦ Ceramic disc operation. This costs more but helps to resist scale build-up, which can cause spindle valves to jam.

26. May 2011 by admin
Categories: Heating, Plumbing | Tags: | Comments Off on How to Fit Radiator Valves


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