If it is leaking from the spindle, use a spanner
to tighten the gland nut. If that proves unsuccessful, undo
the nut and wind PTFE tape down into the spindle.
If it is leaking at the coupling to the pipe, tightening
the nut gently may be all that is required. If that proves
unsuccessful, then drain the radiator. Then undo the cap
nut, take off the fitting and replace the olive. Either
smear the olive with silicone sealant or wind some PFTE
tap around the olive before retightening the cap nut.
If the leak is caused by corrosion, a new radiator
needs to be fitted. In an emergency a temporary repair can
be made using a plastic resin filler. To replace the radiator,
turn off the valves at each end. Remove the cap which holds
the lockshield in its position, then fit a key on the top.
Turn off the manual valve at the other end. Now the radiator
can be removed and replaced. Use wire wool to clean corrosion
from the threads of both adapters and blanking plugs and
either smear with silicone sealant or wrap PFTE tap around
the threads. Check that the wall brackets are secure before
replacing the radiator. Connect the valves to their adapters.
To help with any future corrosion problems, flush out the
existing system with clean water and add a rust inhibitor
to the water.
If you need to repair the valve, you will need to
drain part, if not all of the system. Check that the replacement
valve is the same type as the one being removed. A different
kind of valve may not align with the water pipe. Use an
adjustable spanner, unscrew the cap nuts connecting the
valve to the water pipe, while holding the body of the valve
with a wrench. Unscrew the cap nuts holding the valve to
the adapter in the end of the radiator. You should now be
in a position to remove the valve from the site. Remove
the valve adapter from the radiator by unscrewing it. Clean
the threads in the end of the radiator.
Wrap PTFE tape round the threads of the new adapter and
screw it into the end of the radiator, tightening with a
spanner. Next slide the valve cap-nut and a new olive over
the end of the pipe and fit the valve. Using a similar method
to the dismantling of the old valve - hold the valve with
a wrench and align it with the adapter. Then tighten the
cap nuts holding the valve to the adapter and the cap nuts
holding the valve to the water pipe. The system should now
be ready for refilling with water. The site of the fitting
should be carefully checked for leaks. If necessary, tighten
the cap nuts a little more.
Once the system has been refilled the radiators will need
to be 'bled', this is done by undoing a screw at the top
of the radiator with a special key (usually supplied), this
allows any air in the radiator to escape and the radiator
to fill completely with water. When bleeding a radiator
you should not unscrew the plug completely, just enough
for the air to escape. When water starts to some from the
screw, the radiator is full and it can be closed. If the
whole central heating system has been drained for the repair
then all the radiators have to be 'bled' to allow them to