Isolating a CH pump - I'm not sure

[Clive]

Hi,

My CH pump is easily accessible and has isolating valves above and below. The isolating valves turn easily with mole grips and I believe I shut them off by turning them clockwise and seeing the spindle go into the body of the valve. I undid with a wrench the large nuts holding the pump in place - they undid easily. I had put down plenty of old curtains and cloth around the pump and I wiggled the pump slightly. Water started come out round the seals on the pump inlet and outlet. I let the water run around the seal for a minute (maybe it was only 30 seconds) and then I lost my nerve and refitted the nuts. I'm really concerned that if I remove the pump and I haven't actually closed the isolating valves that I will get a deluge of water that I can't stop. How long should I expect the water to flow out of the pump so that it empties and I can feel confident the system is actually sealed?

The pump is in an upstairs room so I have visions of flooding the room below and bringing the ceiling down.

Separately, if other valves on the system with "old style" tap heads or "gate valves" are seized (yes, that old one !) what is the risk of the valve "falling apart" if I try to free them using some kind of wrench? Is there some "miracle" penetrating oil that will help free the valves or is it best to drain down and have them replaced - then use them every six months to stop them seizing?

Thanks

Clive

[Harry Bloomfield]

Clive formulated the question :

Expect about a litre to come out, but keep in mind these are gate valves which never fully seal the flow. Clock-wise looking at the valve from the spindle is off and the spindle should also wind into the body.

If the valves turn so far, then stop fairly solidly, that is a good sign that the valve is tight shut. You might lay some plastic sheet down to catch most of it, with something suitably absorbent on top.

Undoing the top nut only and allowing that to drain first, means you can get a better idea of how much water is passing the two valves. That way you are dealing with less initial bulk of water escaping.

Don't over tighten the valves with the mole grip - they are only intended to be closed with a small hand wheel and could be damaged.

[Simon]

When I tried to replace my CH pump, I found that the 20-year-old gate valves did very little isolating at all, with large quantities of water flowing through them even when "closed". In the end, I had to drain the system. I replaced the gate valves with ball valves, which are supposed to perform better.

[Fred]

In this case he can turn all the upstairs radiators off and part drain the system to the level of the pump. Sounds a far easier afair.

[TheOldFellow]

Close and open all valves, gate or ball, throughout the system once every six months or so. That way you dislodge any scale, and other muck, before it gets too thick.

Ball valves can be sealed open with scale. And gate valves can have their gates filled with almost anything - then they jam.

R.

[Dave Plowman (News)]

Fact of life with gate valves in a hard water area - the seats get clagged up and no longer shut off the flow fully.

Best to drain down the system - the inhibitor could probably do with a change anyway.