Megaflow Cylinder - Failed pressure relief valve on water inlet

[SithLordHood]

Hi,
I have noticed a leak on my Megaflow cold water inlet pipework, after the isolator, before the cold inlet to the bottom of the cylinder. It is leaking between the nut and the base of the 8bar pressure relief valve. It is loosing about 1 drip a second so cant stay like this.
I isolated the input supply then removed the tee piece and tried to make the connection good to the pressure relief valve but to my surprise there is no evidence of any gasket fitted, it just seems the plastic base of the pressure valve sits inside the nut that screws onto the t-piece. Perhaps the plastic is worn? But it still does not seem like a good design if its designed to withstand 8 bar of pressure..

Until i can get another replacement 22mm tee and pressure relief valve part i hae capped off the tee for the pressure relief valve using a 22mm blank.
Am i ok to do this as a temporary repair (5 days?)

The only slight worry i have is whe the cylinder is being heated, the water pressure will increase as it gets hot and as the t-piece features a non return element, to prevent the hot water lowing back into the supply pipe the pressure will build up. Not sure in practice if this will be an issue, i cant imagine it would get anywhere near 8 bar but i dont know to be honest.

Perhaps i can turn the temperature down on the megaflow so the water wont be heated as hot for the interim period?

Thanks!

 

[cross thread]

No it’s not ok

 

[trojanhawrs]

There's a reason it's set at 8 bar. If your ev fails it will get much, much higher than that until it springs a leak/explodes something catastrophically. The fact it's leaking there is not a good sign, makes you think it has seen flow which it shouldn't under normal operation. Turn your boiler off and let your system cool before you touch anything. Put it back on with some ptfe tape around the plastic shoulder to try and plug it a bit for the mean time.

 

[cdbe]

Put it back on. Looks like a flat o ring. The drip is fine for a few days and might stop your house blowing up.

 

[SithLordHood]

Thanks or the advice guys, appreciated.

Found the replacement 8 bar expansion relief valve to fit direct onto the t-piece.
Boiler off until it arrives and is replaced.

 

[Madrab]

The valve seals with the bottom O-Ring. Silicone grease new one before fitting



TBH though, this is a perfect example of why these appliances should not DIY'ed!! They are a regulated piece of equipment, covered by legislation, therefore a person needs to be qualified to work on them, especially their safety devices! The fact that the PRV was removed and capped and the appliance still used is a perfect example of why a person needs to be qualified, they can be very dangerous and ultimately take the roof off the house.

This is obviously worst case but all they did was cap both safety devices and then had a run away electrical heating element - watch from 2:10

 

[SithLordHood]

All fixed, new pressure relief valve fitted.