I want to drain my central heating so that I replace a faulty mid-position
motorised valve.

Now I have found two drain cocks in the system.

i) On the bottom of a downstairs radiator - lowest point in the system
ii) On the return pipe to boiler. This is about 6.5 feet so is above
downstairs radiators

Now I have questions about them both.

The low drain cock (i) has a square drive the same dimensions as a radiator
vent. However, it is in a recess which is circular but with one flat edge.
This means you can't get a vent key into it. At first I thought the flat
was where it had been bashed by the installers but on closer inspection it
has been manufactured like that. Is there a special tool to operate this?

The high drain cock (ii) can be opearated easily but I don't see how this
will drain the system. Is this because it is only meant to drain the
upstairs or are you meant to have the pump on so that the water is pumped
out. If you are meant to use the pump, how do you get it to operate without
the boiler on.

Thanks for any advice.

Cheers,

Nigel

On Mon, 8 Sep 2003 19:18:19 +0100, "Nigel"
wrote:

I want to drain my central heating so that I replace a faulty mid-position
motorised valve.

You may not need to drain the system. With some motorised valves the
actuator assembly comes off the valve head and can be replaced without
undoing the pipework. If it is one of those then you may well find
that it is the actuator assembly that is at fault, not the valve
itself. Makes it easy to replace the faulty component.

Have you tried taking the head off the motorised valve to see?

PoP

Thanks for the useful advice. No this valve burns a motor head out in a
couple of months. (it's had three heads in the last year!) With the
actuator off, I tried turning the spigot with a spanner. It was very stiff,
so i reckon the valve itself needs replacing.

Cheers,

Nigel