expansion vessel

[KEITHBLACKWOOD]

i have had my new worcester 28i junior for four years and had to replace the expansion vessel 3 times, anyone any ideas why, it is an 8ltr only running 7 rediators

 

[Bernie2]

Depends on a few things.

Is your system water very aggressive?

Is it a membrane expansion vessel where the water is in contact with the expansion vessel walls?

Is it a bag expansion vessel?

Try a pH test to find what is in the system water.

 

[stevetheplumber]

are you replacing it because it leaks ? normally all they need is pumping up

 

[Puddle]

yes.why are you replacing expansion vessel?

 

[KEITHBLACKWOOD]

I am changing the expansion vessel as each time i turn on the heating the pressure goes way over scale and lifts the relief valve therefore shuuting down the system with lack of pressure

depends on a few things.

Is your system water very aggressive?

Is it a membrane expansion vessel where the water is in contact with the expansion vessel walls?

Is it a bag expansion vessel?

Try a ph test to find what is in the system water.

the water is fine and yes it is a diaphram vessel

 

[david williams]

what makes you think it is expansion vessal at fault.i thought on this boiler it was a 6 ltr expansion vessel charged to 0.5 bar fot static head of 5 mtrs

 

[Bernie2]

Hmm!

As you did not say the problem was pressure related I supposed it may have been corrosion. In the diaphragm vessels the water expands into one half of the vessel and so comes into contact with the walls of the vessel, hence asking if the water was very aggressive and attacking the walls of the vessel causing holes.

I asked about the bag expansion vessel, because the water expands into a bag inside the vessel and so doesn't touch the walls. Which would indicate it wasn't an aggressive water problem.

The pressure rise sure sounds like a faulty expansion vessel, but as others have said "Is it the right size?"
"Is the charge pressure okay?"
"Is there water coming out the Schroeder valve when you press it?"
"Can you hear air going into the system water when you pump the vessel up?

If, as no doubt you have done, find that the expansion vessel is faulty and its a diaphragm fault the only obvious conclusion that seems open to you, is that the vessel would seem not to be of high quality, that is not to say they don't meet the minimum standard.

 

[KEITHBLACKWOOD]

Hmm!

As you did not say the problem was pressure related I supposed it may have been corrosion. In the diaphragm vessels the water expands into one half of the vessel and so comes into contact with the walls of the vessel, hence asking if the water was very aggressive and attacking the walls of the vessel causing holes.

I asked about the bag expansion vessel, because the water expands into a bag inside the vessel and so doesn't touch the walls. Which would indicate it wasn't an aggressive water problem.

The pressure rise sure sounds like a faulty expansion vessel, but as others have said "Is it the right size?"
"Is the charge pressure okay?"
"Is there water coming out the Schroeder valve when you press it?"
"Can you hear air going into the system water when you pump the vessel up?

If, as no doubt you have done, find that the expansion vessel is faulty and its a diaphragm fault the only obvious conclusion that seems open to you, is that the vessel would seem not to be of high quality, that is not to say they don't meet the minimum standard.

thanks for your reply, it is pretty much what i thought.
I am going to fit an external unit and put inhibitor in the system, see if i have any more luck

 

[david williams]

have you been fitting worcester parts ,is this vessal external to boiler

 

[KEITHBLACKWOOD]

have you been fitting worcester parts ,is this vessal external to boiler

THE PREVIOS PTS WERE WORCESTER BUT THIS TIME WILL FIT EXTERNAL.
have dumped the water pressure and charged the EV and showing pressure back on system so reacon it is leaking past diaphram