Page 524 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

The City & Guilds Textbook: Plumbing Book 1

Replacing faulty radiator valves, step by step

Faulty radiator valves are easy to replace provided that the new valve is of the
same body size as the valve being replaced. Over the years, there have been
many different styles and sizes of valve body and, sometimes, older valves
are bigger than their modern equivalents. In this case, pipe alteration may be
needed, which should be conducted with care to ensure that the customer’s
decorations and floor coverings are not damaged. To replace a like-for-like valve
(assuming the radiator valves old and new are the same size), go through the
following steps.

1 Isolate the F and E cistern at the service valve. If it is a sealed system, this
will not be necessary.
2 Locate a suitable drain valve, attach a hose and drain the system. Take care
that the system contents are disposed safely to a drain as they will probably
be very dirty, especially if the system is an old one. The black water will stain
all it comes into contact with.
3 As the system drains, open the air release valves on all radiators, starting
upstairs, then working to the downstairs.
4 When the system is drained, carefully loosen the radiator valve compression
nut and union and remove the valve.
5 Remove the old radiator union from the radiator and compression nut and
olive from the pipework.
6 Wrap PTFE tape clockwise around the new valve union and screw it into the
radiator using a radiator valve Allen key.
7 Slip the new compression nut and olive onto the pipework. If the old olives
have crushed the pipe too much, then the pipe may have to be replaced.
8 Put the new valve onto the pipe, then hand tighten both the compression nut
and the radiator union.
9 Using an adjustable spanner, and taking care not to damage the chrome
plating, tighten both the compression nut and the radiator union. You may
need to hold against excessive valve movement by using water pump pliers.
Take care with the chrome plating.
10 Ensure all radiator unions and compression nuts are fully tight.
11 Turn off the drain valve. It may be a good idea to replace the drain-off valve
washer at this stage. Drain valve washers quite often go stiff and brittle with
the heat from the water.
12 Turn off all air release valves.
13 Turn on the service valve to the F and E cistern or (if applicable) reconnect
the filling loop and refill the system.
14 Bleed the air from all the radiators starting downstairs then upstairs. Leave
the radiator with the new valve isolated at this stage. This will be the last
radiator filled.
15 Open the new valve to the radiator and bleed the air from it. Check for leaks.
16 Replace the fuse in the fuse spur and run the system to full temperature to
ensure that the new radiator is working perfectly.
17 If corrosion inhibitor had been added to the system in the past, this will need to
be replaced. It must be replaced like for like. If this is not possible, the system
should be flushed several times to ensure removal of all previous inhibitors.

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