Changing Main Stop Cock

[vetinry]

I'm currently installing a new kitchen in our house, and have noticed that the existing main stop cock is leaking a little.

The pipe entering the house is blue MDPE and measuring roughly, I assume that it is 32mm (house was built in 1987)

The current stop cock joins directly to the 32mm pipe and then 22mm pipe appears from the other end.

I cant quite work out exactly how the reduction is working becuase there is an earth clamp which I need to remove.

What is the best way of reducing from the 32mm MDPE into the 22mm copper pipe.

I was planning to use a good quality 22mm stop cock and reduce the 32mm pipe down to 22mm using a coupler.

But I can't seem to find exactly what I need - most of the couplers seem to be for joining 2 pieces of MDPE together eg 32mm to 25mm.

Please can anyone help tell me exactly what I need to do this?

Many thanks

Steve

 

[JohnD]

measuring roughly, I assume that it is 32mm

Please measure it precisely to make sure. Or it may be printed on the side of the blue pipe.

if it is 32mm blue MDPE it must be quite new, I am surprised it is leaking. Where is the leak coming from? The spindle, or one of the pipe connections?

 

[vetinry]

Hi John

I'm guessing the pipe has been there since the house was built in 1987.

It's not very easy to see where the leak is coming from but I think it's coming through the spindle - is it ok to try and gently tighten?

Steve

 

[JohnD]

a photo will help a lot.

//www.diynot.com/forums/viewtopic.php?t=129539

Many better-quality brass taps have a gland nut round the top of the spindle that you can tighten. Slight spindle leaks tend to seal themselves with limescale unless they are turned often

 

[kevplumb]

stop tap parts

• kevplumb
• 23 Sep 2010
• 2

tighten number 5

 

[JohnD]

good pic

 

[TicklyT]

If the gland nut doesn't respond to nipping up , unscrew it, twist a length of PTFE tap into a round 'string' and pack that around the shaft under the nut.

 

[londonboy]

If the gland nut doesn't respond to nipping up , unscrew it, twist a length of PTFE tap into a round 'string' and pack that around the shaft under the nut.

I've done this a few times with some success, what exactly does the PTFE do?

 

[kevplumb]

when you tighten the gland nut it packs it down and seals the spindle

if you think of it being in a round box with the spindle in the middle

it cant go down up or sideways so it goes inwards

 

[vetinry]

I've taken some pictures which hopefully might help.

You can clearly see a water drop on the bottom of the spindle.

Also, it's pretty glued up with limescale. If I didn't have to replace, that would be fantastic. Are there user servicable parts inside the stop cock?

Thanks for the ongoing advice

Steve

Untitled

• vetinry
• 29 Sep 2010
• 1

Untitled

• vetinry
• 29 Sep 2010
• 1

Untitled

• vetinry
• 29 Sep 2010
• 1

 

[kevplumb]

give the gland nut a nip

and hold the body with another wrench while you do 1/4 turn should do it

 

[vetinry]

Fantastic

Thanks as always for all the great advice. Hopefully I won't need to replace it after all

Cheers

Steve

 

[JohnD]

If the blue pipe is running upwards, it looks to me like most of the leak is from the upper compression joint (unless it is dripping from the joint above). Undo it, clean all surfaces with wire wool or green kitchen scouring pad, put PTFE tape round the olive, and reassemble. PTFE tape is very good at making compression joints watertight. Some professionals don't use it because they claim their joints never leak...

If you scour all the copper pipes bright, you will easily see the marks of any remaining leaks in a week or so.

 

[vetinry]

Thanks John

Yes, the blue pipe is running upwards - sorry - should have rotated the photo.
But I don't think that any of the marks on the main body are new - ie I think that the top compression joint is ok - I think it's only the spindle that is leaking.

Cheers

Steve

 

[TicklyT]

If the gland nut doesn't respond to nipping up , unscrew it, twist a length of PTFE tap into a round 'string' and pack that around the shaft under the nut.

I've done this a few times with some success, what exactly does the PTFE do?

The gland nut squeezes the gland packing against the valve spindle in the same way a compression joint squeezes an olive onto a pipe.

The problems often start when you close a valve for the first time in years. As you wind the spindle down,all the bits of limescale and other crud stuck to it tear chunks out of the soft packing in the gland, so it leaks when you turn it back on. The PTFE replaces the lost packing material, so there's still something for the gland nut to squeeze onto the spindle.
Traditional packing materials included hemp and tallow, and asbestos fibres in graphite grease

A piece of butchers string coated in candle wax works well too.

Setting the gland is often a compromise between achieving a perfect seal, and still being able to turn the valve spindle. I often err on the tight side for a rarely used valve, as I'm prepared to slacken off the gland nut a tad if I need to operate the valve.