Unvented Cylinder & Expansion Vessel Location

[Mike Clements]

Just after a sanity check. Replaced the EV at the weekend, water coming out of the valve at the top. Drip still present in the tundish drain. Confirmed it's not the boiler or tank PTRV, it's coming from the combination valve unit PRV. Before I replace the PRV, I'm unsure that the EV is in the right place. The system was installed by a professional in 2011. I understand the EV has to sit on the cold supply to absorb any expansion and back pressure to the mains, however if the combi valve unit has a check valve installed, and I think it has, the expanding water won't get to the EV in this current set up.

Appreciate any advice here.

 

[muggles]

Are you G3 Registered? If not, you shouldn't be working on this

 

[ScottishGasMan]

You shouldnt be working on a unit like that without the proper qualifications for it, ones that I doubt the "proffesional" had either. Buy you are correct. the Expansion vessel is doing nothing for the system where its currently located, due to the non return valve in the safety group

 

[Mike Clements]

Thanks for the reply. Thought it would be ok to change the EV as I'm not working on the boiler, gas supply or heated side. Did not know you need qualifications to do this task. I've had the boiler serviced every year, initially by bosch worcester and then by a local firm, can't understand why this has not been pointed out previously. Am I right in stating the EV should be on the LHS of the safety unit. The system has worked as expected for nearly 10 years.

 

[ScottishGasMan]

Yes, should be on the left side on the insulated pipe, theres sometimes a specific fitting on that valve set to plumb it to.

They call it G3 qualification as if installed incorrectly and theres a failure they can blow up with the same force (if not greater) than a gas explosion.

It's incredibly rare (in this country anyway) but it's possible and has happened

 

[ianmcd]

You need a G3 qualified pro in , there are a few things wrong with that install that need addressing

I've had the boiler serviced every year, initially by bosch worcester

But did they service the unvented cylinder? this should be done every 12months too,just because they serviced your boiler does not mean they were G3 qualified, not every gas engineer/plumber is

 

[Mike Clements]

Thanks for the reply. I've not asked specifically for the cylinder to be serviced. No one mentioned the requirement previously. Understand its up to the home owner to arrange these things but I thought I was doing the right thing getting the boiler serviced every year. Can you elaborate on the few things that you see are wrong. I will look into a G3 registered tradesman near me. As this system is nearing 10years of age was it ever a correct installation? Has the specification and standards changed since the install in 2011. Appreciate the help.