How To Change A Radiator Valve
To change a central heating radiator valve, the first thing to do and I know this may sound stupid is to turn your boiler off, and stop the water circulating. Find your low point draining valve or outlet and drain the system water level to below the level of the radiator valve your looking to change. If its on the first floor then just drain the water on that floor only.
Its still worth being careful to protect your home so put down some towels and have some large utensils that can fit under the valve ready to catch any small amounts of water that may be left in the radiator. Using a fixed or adjustable wrench you can then slowly loosen (anti clockwise) the valve nut. If water comes out either drain the system more or catch small amounts in the utensit/towels below.
Fully open the Nut on both ends of the valve, the one on the pipe going into your radiator as well as the one on the other end of the valve where the pipe goes to the floor or wall (depending on your radiator system). Remove and dispose of the old valve. You need to try and remove any washers/plumbers tape or brass rings that will now be sealed onto the tail pipes. These help the valve to seal when in use. But you need to replace these when installing the new pipe. If you can not remove them, it might be best to call a plumber as you will likely need new pipes or extensions if you cut that section off.
New Valves come with TRV Control heads and a lock shield valve to go on the outlet pipe of the radiator.
The new valve for a Central heating radiator must be an approved EN446 TRV valve, these will likely carry a KEYMARK or other identification to indicate compliance. Cheaper non compliant valves may break, block up, leak or malfunction. The EN446 valves are not expensive so stick to them.
Assuming you have enough tail pipe showing to fit the valves now you should then fit the valves comfortably, with brass rings/washers/ptfe tape to ensure the seal between the nut and pipe is entirely closed and sealed. Tighten just to tight and a turn more on both ends of the valve.
When both ends are replaced then open the valve (and open the lockshield). Using the boiler filler loop refill the boiler to the indicated pressure (green zone on boiler pressure guage). When full you will need to bleed all the radiators again and refill the water further if pressure drops again. It may take a couple of cycles to get all of the air out and the pressure back to the desired level.
Lynwoodhome.co.uk sell a good range of Central Heating TRV Valves. They are all keymarked and conform to EN446. Standard TRV Valves come with free lockshield and are available with chrome or white heads. The premium Slimline valves also come with lockshield but are available in Black, White or Chrome. All Lynwood Radiator Valves come in “angled” options for pipes coming from floors or “straight”, which can be used I you have an irregular pipe arrangement.
Priced at £14.99 - £24.99 the range is cost effective, safe and will compliment your home.