Type of Pump Isolator Valves to use ?


Postby egeoffreydavies » Thu Dec 09, 2010 1:23 pm

Hi all, first post.
I have solid fuel central heating and the grundfos pump has started making noises after 14 years. I have bled the pump but to no avail. Having acquired a replacement, I tried to turn off the isolator valves ( the 90 degree turn ball type) but they immediately started leaking at the screw. I managed to fiddle the screw around to stop the leaks and decided that the best way to proceed is drain down the system and replace the isolator valves at the same time as the pump. I have bought 2 new ball type isolators, but after reading some of the forums also got 2 gate valve type isolators which I intended to use. Only thing that troubles me about these is that the internal bore is much smaller than the ball type, and that the "gate" doesn't retract quite fully. Will this mean restricted flow ? The existing system is excellent on gravity feed with all the upstairs rads being HOT. Should I replace like for like isolators or go with the gate valves ?
Thanks for any advice, Geoff
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Postby plumbbob » Fri Dec 10, 2010 1:05 pm

I can't see that it matters which you choose. Just be guided by which give the best in bore size.

Gate valves don't absolutely open fully, and do have the smallest piece of the gate still protruding. This does not effect the performance.
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Postby Whitcop » Fri Dec 10, 2010 3:57 pm

I would recommend pump Gate valves available in 28 & 22 mm sizes. They dont restrict the flow when fully open.

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