Water dripping through Tundish after 2 PRV replacements

A

Alex Burton

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Hello,

Wonder if anyone has any ideas or thoughts, i've even spoken to a plumber who is a little confused.We have a unvented Stelflow cylinder which in the past year has had 2 PRV replacement and a temp pressure release valve to. While this stopped the dripping through the tundish initially, after a few months the issue has just come back.

Does anyone have any ideas what else that could be causing this?!

I have a water softener and have had a pressure reducing vale (5bar) fitted to the house to. If anyone has any ideas what to check that would be great
 

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Where is your pressure vessel? It should tee between the combination valve & the cylinder cold feed. Why is your hot water set to 65degrees. The water at the top could be as hot as 85 degrees.
 
Plus, your other PRV should be at 3 bar. That’s what the cylinder one (in the wrong position) would be at.
 
Also make sure the water softener is bypassed when filling heating system. Boilers etc font like softened water.
 
Thanks for all the replies, ill do my best to answer -

Where is your pressure vessel? It should tee between the combination valve & the cylinder cold feed. Why is your hot water set to 65degrees. The water at the top could be as hot as 85 degrees. - The expansion vessel is above the tank, i'll grab a pic. The water has always been set like that but its never really hot hot as such. We moved in last year so have mainly just left things as they are. I had an electrician come fit a hive last year and he didnt actually think that thermometer was doing anything.

Plus, your other PRV should be at 3 bar. That’s what the cylinder one (in the wrong position) would be at. - From looking at the PRV its a 3bar for cold and 6bar for hot ( i think)

Also make sure the water softener is bypassed when filling heating system. Boilers etc font like softened water. - As far as i know its bypassed. We had the first issue before we had a softener installed in October but the previous owners had a long term softener installed. The water in the tank is softened as far as i know.
 

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That's a really poor installation that doesn't fully comply with the G3 regs. specifically the safety valves and tundish arrangement.
I suspect there may be other issues leading to the problems you have.
It's best practice to locate the pressure reducing valve set above the cyclinder to ease maintainance and avoid a cylinder drain down when repairs are necessary.
Needs a G3 licenced installer to check it out and rectify the faults.
Download the cylinder manual and check if you have a balanced cold takeoff and whether there's a chance some cold taps are back presurising the cylinder via the hot pipework.
 
PRV - pressure reducing valve. Sorry.
Could you get a photo low down showing the combination valve side on?
The vessel “might” have been taken from the balanced cold connection & may be the wrong side of the non return valve.
 
Here you go
 

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If you tap the expansion vessel, does it sound hollow or is it a dull thud, like it is full of water?
 
Sounds like it’s full to me. I tried to upload a video but appears the forums don’t allow videos
 
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