Replacing 15mm Stopcock

BennyC

BennyC

BennyC

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Joined
25 Sep 2006
Posts
14,453
Morning,

I'm fairly certain the Stopcock for my garden tap has had it. It's always leaked very very slightly (8 years) or so from the actual turn assembly so has regularly been turned on/off each time the garden tap has been used.

Water pressure to the house today is fine and the garden tap is only a few months old and of decent quality so I think that perhaps the stopcock is no longer opening fully?

(There is flow to the garden tap but it is probably about 50-60 of normal. I was using the sprinkler moments before, turned the stopcock off and then back on and flow was reduced - tried several times)

I have a new 15mm fitting, plumbing for the most part intimidates me despite being a reasonably competent DIY'er, practical and quite hands on.

Armed with a set of adjustable spanners, PTFE tape, towels a box full of swearies and of course the knowledge to turn the mains stopcock off first :p is there anything else I should know? or any tips?

Will watch a few guides at lunch today but I'm thinking the process is along the lines of:

  • Turn off mains stopcock
  • Open garden tap to allow anything to drain.
  • Holding the stopcock in place, to stop it spinning, loosen each nut in turn.
  • Remove stopcock, olives and nuts.
  • Slip nuts & olives on to pipes.
  • PTFE threads on stopcock (if required?)
  • Position stopcock, hold in place, tighten nuts.
  • Turn mains back on.
  • Check for leaks.
Thanks,

BennyC
 
Yep that's all you need to do, you'll find after doing a few plumbing jobs it's not as intimidating as you think, I actually quite enjoy it, plumbing tasks always takes longer than you expect though!
 
Plan sounds reasonable to me and definitely put PTFE tape on both compression threads (wrapping the same direction that the nuts will turn when you tighten).

Personally I would consider fitting a 15mm isolator valve before the stopcock in case you need to service it again in the future, so you'd only need to turn off the supply to the garden tap, rather than the whole house.

Apart from that just have all the bits ready, because you'll obviously have no water to the whole house for the duration of the job.

Do you have a 15mm pipe cutter and something to deburr the copper, just in case a) the stopcock doesn't fit in the existing gap and / or b) you decide to fit an isolator?
 
Fireskull said:
Yep that's all you need to do, you'll find after doing a few plumbing jobs it's not as intimidating as you think, I actually quite enjoy it, plumbing tasks always takes longer than you expect though!
Click to expand...

I think it's just the prospect of it going Pete Tong and needing to call for backup :p Water everywhere etc


Participant said:
Plan sounds reasonable to me and definitely put PTFE tape on both compression threads (wrapping the same direction that the nuts will turn when you tighten).

Personally I would consider fitting a 15mm isolator valve before the stopcock in case you need to service it again in the future, so you'd only need to turn off the supply to the garden tap, rather than the whole house.

Apart from that just have all the bits ready, because you'll obviously have no water to the whole house for the duration of the job.

Do you have a 15mm pipe cutter and something to deburr the copper, just in case a) the stopcock doesn't fit in the existing gap and / or b) you decide to fit an isolator?
Click to expand...

Thanks, noted to wrap the PTFE in the same direction!

That's a good shout though I don't have a cutter or too much room between where it comes off the main riser and then bends 90 degrees in to the wall & heads outside. There is a 'one-way' flow valve fitted there for some reason, after the stopcock. I recall the plumber/house builder mentioning it but it was 8 years ago...

Fortunately it's just me at home but I will run a few litres through in case I do end up waterless in the worst case eventuality.

The stopcock I have looks to be identical so hopefully a straight swap... (famous last words).
 
Participant said:
Plan sounds reasonable to me and definitely put PTFE tape on both compression threads (wrapping the same direction that the nuts will turn when you tighten).
Click to expand...
Compression fittings don't seal on the threads so there's no reason to add PTFE tape.

They seal on the olive. If that's clean and compressed correctly it won't leak.
 
If everything is clean and round a compression fitting will work without any additional help.

I do tend to put a smear of petroleum jelly on the threads as that makes tightening them down easier.
 
bremen1874 said:
If everything is clean and round a compression fitting will work without any additional help.

I do tend to put a smear of petroleum jelly on the threads as that makes tightening them down easier.
Click to expand...
I have don't that before to aid tightening up.
Plumbers mate would be preferred to PTFE imo of you wanted to use something.
 
Great success but the low pressure to the garden tap seems to be persisting.

Initially I removed the garden tap prior to changing the SC, to isolate whether it was the actual issue. Came out under the same pressure as before. No change after fitting the new SC and opening both the main SC and SC for the garden tap fully.

It was whining very loudly. Turned off and on again and it disappears. Wondering if the NRV could be an issue or if perhaps a blockage. Mains pressure is fine. Any suggestions?

Edit: Turns out that air in the system might have be the issue, ran the taps upstairs & flushed the toilets etc and pressure to the outdoor tap shot up. Weird. Would using the SC/Garden tap simultaneously/alternatively caused a potential air issue?

For those a little more experienced, I wasn't actually able to get the original olives off the existing copper, they seemed pretty well stuck. So (perhaps to some horror) wrapped them a few times in PTFE and tightened up.

The new stopcock looked to be marginally shorter and it *touchwood* is sealed but think maybe the olives should be a bit further along each section of pipe to make up for the shortfall.

Would you suggest replacing those copper sections with new pipe and using new olives? Or will tightening the nuts have moved them along the pipe to the same effect?

Also those look to be push-fit fixing on the remainder of the riser but they didn't seem to want to come apart like I would expect.

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