Jet Range by Wolseley - DN20 Isolation Valve

[Trevor Rix]

Is anyone familiar with the Jet Range isolation valve DN20 which is operated by screwdriver? Does this valve have a known design fault causing it to fail?

During the retification of the leak in my other thread "Wear And Tear Causing Leaks?" (in another part of the system), the plumber approached this valve behind the boiler intending to switch off the mains cold water supply to the system in question. In doing so he removed the pipe insulation close to this valve so he could access the screwdriver slot. To his amazement, as a result of removing the insulation, the copper pipe popped out of one end of the valve before he was able to apply the screwdriver. Mains water pressure spurted out, causing the plumber to have to stop the 20mm flow with his thumb. He was alone at the time!

Some time later, I walked past the builing and heard a shout for help. It turned out that I could not help by turning off the mains water immediately because there was no other isolation valve in the area. I had to drive half a mile to the water meter at the entrance to my property to turn off the water at the meter there.

Anyway, although the plumber commented at the time that this valve was known to have a faulty design and was no longer on sale as a result, he wants to charge me for a new valve of a different type and for his time because the original valve was by now out of warranty. Is this fair?

 

[ShaunCorbs]

any pics of the valve ?

 

[Trevor Rix]

This is the valve in question.

 

[ShaunCorbs]

thats not a valve its a non return or check valve eg

Pegler Yorkshire -

and it would fail if its not installed correctly eg not tight enough

 

[Trevor Rix]

On your Pegler example, how does the copper tube connect to the valve? Is it the same as my photo in that the tube appears to be just inserted into the plain end then tightened?

 

[ShaunCorbs]

yea normally a brass olive in the bottom

 

[Trevor Rix]

So, would it suggest that the installation of this valve was not fully tightened?

 

[ShaunCorbs]

So, would it suggest that the installation of this valve was not fully tightened?

yes or mis installed eg not fully in or missing an olive etc or not installing a liner inside the alk pipe

doesnt let go for no reason if its the fittings fault i would expect to see the collar to pop / threads to fail etc

 

[Harvest Fields]

yes or mis installed eg not fully in or missing an olive etc or not installing a liner inside the alk pipe

doesnt let go for no reason if its the fittings fault i would expect to see the collar to pop / threads to fail etc

Or the engineer the other day did something wrong whilst there.

 

[DXCross]

I’m not even sure that’s an isolators with the screw driver slot? Isn’t it just a means of checking the NRV is working?

 

[Harvest Fields]

Or the engineer the other day did something wrong whilst there.

Either way. It would be to hard to prove and get compensation now. Unless it was fitted last week.

 

[Trevor Rix]

ShaunCorbs, You mention alkathene pipe. I am talking about copper pipe.

Is my valve in question suitable for use with copper pipe? Could that have been the problem?

 

[ShaunCorbs]

Dn is normally the dia of the pipe eg dn22 for 22mm tube

What size pipe was it fitted on ?

 

[Trevor Rix]

The valve is marked DN20. The inside diameter of the plain holes each end are 20mm, maybe 21mm. Don't know the size of the copper pipe each end without going and trying to measure it.

 

[Trevor Rix]

Copper tubing - Wikipedia

"In the plumbing trade the size of copper tubing is measured by its outside diameter in millimetres. Common sizes are 15 mm and 22 mm. Other sizes include 18 mm, 28 mm, 35 mm, 42 mm, 54 mm, 66.7 mm, 76.1 mm, and 108 mm outside diameters."

So how does 20mm fit in this scenario?

 

[ShaunCorbs]

Would need a pic

 

[Trevor Rix]

What pic would you like? Please see the two photos of the valve earlier in this thread.

 

[ShaunCorbs]

Where it was installed

 

[Trevor Rix]

In the yellow circle.

 

[ShaunCorbs]

That’s 22mm pipe so I would say not the parts fault the installers at fault

With it being 20mm it’s for alk eg watermains etc

What’s with the two flexis ?

 

[Trevor Rix]

So, are you saying that the installer is at fault for using a valve designed for use with 20mm alkathene on a 22mm copper installation?

I am guessing that the two flexibles pipes were used as an easy method of connecting the copper sections together? Looks rather Heath-Robinson to me.

 

[ShaunCorbs]

Correct it won’t fit as you’ve measured the hole is 20mm so must of been rammed in or something

Them flexis arnt rated for heating so best get them replaced

 

[Trevor Rix]

Thank you ShaunCorbs and everyone else who contributed. Much appreciated.

 

[Brambles]

Trevor,

DN20 is an ISO sized fitting for 3/4 inch pipe (26.66mm). It is not intended to be used with 22mm pipe. With respect to copper pipe it is intended for 3/4 inch outside diameter.

Normally if metric and imperial fittings are mixed up with 15mm and 1/2inch diameter pipe they generally work (not always). However the size difference between 22mm and 3/4inch is too great for success to be a possibility.

This would account for the pipe “popping” out - but I would be surprised that the pipe remained in place and leak free since the original installation - unless it had been “mumified” with ptfe tape!!

The Jet valve in question is a non return valve, the screw is for testing, it is not intended for isolation, there should be a proper (ball) isolation valve at the point of entry into the boiler house - the installer will have fitted one - he/she won’t have driven 1/2 mile to isolate the supply.

The flexibles look to be a makeshift filling loop. They should be replaced with the correct WRAS compliant ones.

If I were in your shoes, I would check out the system on a line by line basis, both for the design ( heat balance and flow calculations) and the specification of pipework and fittings / quality of installation work.

 

[Harvest Fields]

Trevor,

DN20 is an ISO sized fitting for 3/4 inch pipe (26.66mm). It is not intended to be used with 22mm pipe. With respect to copper pipe it is intended for 3/4 inch outside diameter.

Normally if metric and imperial fittings are mixed up with 15mm and 1/2inch diameter pipe they generally work (not always). However the size difference between 22mm and 3/4inch is too great for success to be a possibility.

This would account for the pipe “popping” out - but I would be surprised that the pipe remained in place and leak free since the original installation - unless it had been “mumified” with ptfe tape!!

The Jet valve in question is a non return valve, the screw is for testing, it is not intended for isolation, there should be a proper (ball) isolation valve at the point of entry into the boiler house - the installer will have fitted one - he/she won’t have driven 1/2 mile to isolate the supply.

The flexibles look to be a makeshift filling loop. They should be replaced with the correct WRAS compliant ones.

If I were in your shoes, I would check out the system on a line by line basis, both for the design ( heat balance and flow calculations) and the specification of pipework and fittings / quality of installation work.

So why could he not use a 3/4 olive?