Dave Liquorice wrote:

On Wed, 28 Dec 2005 12:30:32 +0000, Andy Hall wrote:

It should be possible to replace the pump without draining the
system provided that the isolating valves can be turned.

And actually isolate well enough. If they are the gate type the
chances are that they won't close fully and you'll have leak a nasty
black stainy stuff under 10 to 30' head of pressure.

Even if they do shut and isolate you then have the problem of the
flanges not wanting to part company with the pump.

Changing a CH circulator should be a 30min job tops, it rarely is...

I had exactly the same problem about a month ago. I bought a lovely
Grundfos pump, but then discovered that I didn't have big spanners
suitable for undoing the nuts on the flanges.

I contacted a local plumber and assured him that there were isolating
valves, I had the whole job prepared and he only needed to do a bit of
spanner work. He called in on his way home, asked for £25 in cash and
was on his way in well under twenty minutes.