On Tue, 18 Dec 2012 08:48:51 -0800 (PST), harry
wrote:

*Usually the screw slot in the valve stem is lined up with the hole/
port inside the valve. So you turn it so that it is *at 90deg to the
pipe run to shut off.*And parallel with the pipe to open fully.

Understood.

BTW. If a new pump becomes necessary, Check the face to face
dimensions ie between the flange faces that they are the same.
In days of yore there was some variations between pump manufacturers.

Ok.

Nowadays they seem to be standard.

Good news.

Be sure to clean up the flange faces on the valves to a good standard
without scoring/marking them.

I did ...


When undoing the big nuts, try to avoid putting any strain on the
pipework. ie get someone to hold the pump body against the torque.

What I actually did in the end is initially use two pairs of pump
pliers in opposition on the big nuts (watching the pump carefully as I
did so) till one 'gave', then I nipped it back up again. Then I held
the other isolator valve across it's flats and undid the associated
nut whilst the Mrs held the pump body still. The second nut was a bit
harder than the first (as would be expected).

Then pump came out easily, complete with (fibre) washers.

I then dressed both valve surfaces with the fine file on my
Leatherman, till they felt nice and smooth (it was a bit awkward as
both valves were seeping quite a bit and couldn't be improved by
tweaking their position).

I lightly silicon greased both pump threads, put the rubber washers in
place and slipped the new pump in and nipped up the nuts.

(For your second reply)

"Oh and make sure you install any new pump in the same way round as
the existing, ie pumping the water the same way."

Before I removed the old pump I noted it was pumping downwards. The
flow came from the boiler below and up to above the pump where it T'd
across through an air trap and then back down to the input of the
pump. From there to the motorised valve, HW / CH.

It all fired up ok and soon after we were rewarded by a fried 'brunch'
and a nice cup of tea (in the warm). ;-)

Thanks for your advice. ;-)

Cheers, T i m

p.s. Apparently the system hasn't been drained / re-inhibited for some
time so maybe we could do that for her in the spring.