unvented problems

[mjt]

Hi

I have been to look at an ALbion 200l Unvented (THE STAINLESS UNVENTED) cylinder today as it was discharging.

The water is cold so therefore i first looked at the inlet side of things - there is a pressure gauge just before the inlet goes in to the cylinder above the DOC and it reads 7bar!!! so i checked the mains pressure on an outside tap which read just over 3 bar. Therefore would it be logical that the gauge is reading high and is faulty but still indicating that there is problem with the reducing valve? the expansion vessel is an 18l white coloured ZILMET which is fitted directly to the top of the cylinder so would a failure of this cause warm water to discharge with it being sited on the warmer side of the system?

secondly the sealed heating side has a red ZILMET 18l vessel which is not holding pressure - have presses the schrader valve and water comes straight out so i guess the membrane has gone here. it is sited with the valve pointed down (upsdie down). there is no evidence of a leak in the heating system causing the pressure loss.

Just sounding off here chaps so your thoughts would be appreciated.

MJT

 

[diamondgas]

MJT .... It sounds like you've got 2 pressure vessel problems I'd say. On the UVC you can always disconnect the PressReliefValve's to see which one is passing. That's if there's more than one. Usually one on the mains in and a temp PRV on the cylinder. The pressure reducing valve is most likely doing its job and not allowing excess pressure from the mains through, however that allows pressure downstream to build up if the expansion vessel is faulty, which it sounds like it may need recharging. Regards the system exp ... water isn't a good sign ... sounds like it needs replacing!

 

[BLOD]

I'd follow diamondgas' advice and disconnect the discharge pipe from expansion valve to see if it's that.
Have seen quite a few ex.valves fail on unventeds, usually ones that have no charge in the ex vessel.

 

[mjt]

thanks guys - the place is right out in the sticks so just want to avoid the 'i wish i had that on the van' scenario and face a 25 mile round trip to the merchants!!!!

i guess in hindsight of course it points to the expansion vessel - but that presssure gauge showing 7 bar threw me little - its only dripping through the tundish so i guess it can't be that high!!!

Custard says it has never been serviced and its been in 8 years!!!

 

[diamondgas]

Well I'd take a foot pump for definite! And probably a system exp vessel .... Oh and some sandwiches! It's nice havin lunch in the sticks! lol

 

[mjt]

yeah thanks - the foot pump is always on the van.

might treat meself to something nice in my sarnies aswell!!!

 

[mjt]

went back and checked the vessel on the cylinder with my digital tyre pressure gauge and it read 2.55 bar however water flew out - new vessel?