Unvented cylinder inspection

Plumb Tidy · Mar 4, 2021

Hi Lads/lasses just wanted some advice on unvented cylinder inspection. I just took on what seems to be a contract for a block of flats all with direct heating via immersion. The way they have been installed seems a bit off as there is no check valve on the supply to the cylinder. It goes,
Stop tap
Double Check valve
PRV
then tee's off to the cylinder feed and cold water supply for the rest of the apartment.
When draining i noticed if i opened up a cold tap downstairs and opened the TPRV hot water came out the cold tap.
I explained to the customer what's going on and she said she has noticed she has to draw off a bit of hot water out the cold tap before filling a glass of water and thought it was normal.
The cylinders haver been installed in 2004 was the water regs different then? as they didn't require a DCV?
Can i carry out a cylinder safety inspection in this current state?
I have only been doing unvented for around 6 months now so I'm still getting to grips with the certs. I have a picture but my phone won't upload as of yet.

Plumb Tidy · Mar 6, 2021

Ricky said:
Interesting way of installing the cylinder,
Have they sent you the orignal fitting instructions?
Why would you put the pressure gauge before the pressure reducing valve, it doesn't tell you anything helpful, ie is the pressure reducing valve shutting off at correct pressure.
Most cylinders have multiblock inlet valves, where you take the cold supply from, did some plumber fit what he thought was correct?
As Scott asked where is the expansion tank connected, I have always installed the expansion vessel on the inlet, again its to do with Legionella etc you don't want that amount of possible stagnant water on the outlet where it can get warmed up.

Yeah thats it, its to great having the expansion vessel o the to of the cylinder but it is subject to legionella killing temperatures. I guess thats why they have changed the design now on the ultra steels and started making valve blocks so people cannot finesse there way through an install. I have the manufacturers instructions and it has to been installed properly. As you mentioned why would the pressure gauge be before the PRV this is telling you your supply pressure to the house but not the cylinder, maybe worth moving this swell if i want to get fussy.