Gate valve problem

[Miathert]

Hi

I changed a shower pump as the old one gave in. I turned off the gate valve at the hot water cylinder and the gate valve at the cold water tank in the loft for safety. I can't remember how much of a turn the gate valve for the cold tank took to close. The hot water was multiple turns - which I think is normal? Shower pump replaced - gate valve at hot cylinder was multiple turns back on. Gate valve in the loft is only a quarter turn back open - doesn't seem right? Pressure from the shower now fades after running a few seconds and (with pump on) and water is pretty non existent with pump off (previously was working ok but not with usual pressure naturally with the broken pump.)

My questions really are - am I likely to be right in terms of the gate valve is bust? Can I force it open somehow or is it a replacement job?

Also - hitting some problems trying to install the pump I thought I'd change the existing pipe connectors. Using the valve on the connector I tried to drain the hot water feed from the tank - expecting minimal water from gate valve (supposedly shut off) and the shower connector - ended up with a massive bucket of water. Now reading that gate valves are useless. I'm assuming this valve was bust also and probably needs replacing too? Is the assumed fault valve here likely to be causing a pressure problem - even though it's bust open and not closed like the cold one? I guess what I don't know is how much bust open - fully or partially closed!

Sorry - long question and maybe stating some obvious points but trying to figure things out with no real plumbing background.....

Many thanks for any help you can provide.

 

[HERTS P&D]

First thing to do is turn off your water mains, drain down your cold water storage tank. Then remove both gate valves. (get a wet vac in case of any extra water) Then fit 2 lever valves- full bore.

http://www.screwfix.com/p/full-bore-lever-ball-valve-22mm/30584
Turn on mains and remove air locks.

Andy

 

[Hugh Jaleak]

Gate valves are fine when new and for about a month afterwards. Unless they're kept free by turning on and off on a weekly basis they do have a habit of seizing, letting by (a lot), and/or shearing off, usually in the wrong position....

I'd follow Andy's advice, drain down once and fit new valves as he suggests, these are far superior and should outlast gate valves by a long margin.

 

[Miathert]

First thing to do is turn off your water mains, drain down your cold water storage tank. Then remove both gate valves. (get a wet vac in case of any extra water) Then fit 2 lever valves- full bore.

http://www.screwfix.com/p/full-bore-lever-ball-valve-22mm/30584
Turn on mains and remove air locks.

Andy

Thanks Andy - appreciate the response. Supplementary daft question if you don't mind - how do I ensure no air locks? Thanks.

 

[longdogs]

Purge the new pump by running water through it into a bucket with the electric off. Unless you have any high spots in the supply, it should be fine.