Unvented cylinder over pressure

[AndyPRK]

I have a fairly new unvented cylinder.

About 6 months ago I noticed a change in behavior of the hot water tap pressure and the gauge reading 3.5 bar (normally 3)

Recently I happened to noticed 8 bar and the turndish dripping.

I've had the installer in to look at it, who hasn't been very helpful.

What could the problem be ?

 

[Mottie]

The installer!

Edit: I’m not a plumber but it could be the expansion vessel or, and my mum had this, she'd slightly knocked the fill valve lever under the sink so it was constantly pressurising the system.

 

[AndyPRK]

It’s not the fill valve.

Pressure vessel is all built in

 

[Mottie]

Pressure vessel is all built in

That’s another thing my mum had go on her old boiler - the internal expansion vessel on her combi boiler needed replacing.

 

[BoilerBob]

Whoever you get to look at it needs to be certified to work on unvented cylinders. Bob

 

[AndyPRK]

They are! I’m not sure that Helps though lol

 

[muggles]

Sounds like it just needs the expansion vessel or air gap recharging. Pretty basic stuff for a qualified engineer. When was it last serviced?

 

[Mottie]

Sounds like it just needs the explanation vessel

Could you expand on that....

 

[Madrab]

It really needs looked at by a qualified chap who knows what he's doing. If the installer isn't much help then he doesn't know what he's doing and shouldn't have installed it in the first place. The fact that the cylinder is getting to 8 bar is worrying, the pressure relief valve on the combination valve should have opened @3bar and should be flowing quite significantly @ 8 bar, not just dripping.

Is it a Megaflo? Can you give us pics?

 

[ianmcd]

A pic of your setup would help, it is unusual to have a pressure gauge on the DHW side ,you will always have a gauge on the primary water side, but on either side 8 Bar is a bit worrying, a pic is worth a thousand words so would be better

 

[AndyPRK]

It’s a Jet tank.
Pressure relief on tank is 10 bar. So that is why that bit is only dripping.

How do you recharge it?

Do U drain the whole tank and then refill.
As that is what he is saying. As well as other things

How often are they meant to be recharged ?

 

[JimCrow]

Here, page 16 in the Users Instructions,
https://www.wolseley.co.uk/wcsstore...lang.all/on/ly/Jet_Issue_03_Indirect_Only.pdf

 

[AndyPRK]

I guess you press in the relief valve to open it

The air volume within the cylinder will periodically require recharging to ensure any expanded water is accommodated within the unit. A discharge of water INTERMITTENTLY from the pressure relief valve will indicate the air volume has reduced to a point where it can no longer accommodate the expansion. To recharge the air volume:-
i) Turn off the heat source to the cylinder via programmers / immersion isolation switch(es).

ii) Turn off the water supply to the cylinder by turning off the isolating valve at the cylinder, if fitted or the main incoming supply to the house.

iii) Open the lowest hot tap supplied by the cylinder.

iv) Hold open the temperature and pressure relief valve until water ceases to run from the tap and gurgling noise at the valve stops.

v) Close the temperature and pressure relief valve.

vi) Turn on the water supply to the cylinder

vii) The air volume will be automatically recharged as the unit refills. If after following the above actions water still discharges from the pressure relief valve, further advice should be sought from a competent installer or Technical Support

 

[JimCrow]

Twist it to open.

 

[muggles]

How often are they meant to be recharged ?

It should be done as part of the annual service