vaillant turbomax plus 824e expansion vessel replacement?

[Johntheo5]

Yes, it was I said that and yes I have read of the PHE causing this problem.

 

[Hackett123]

Yes, it was I said that and yes I have read of the PHE causing this problem.

Ok that's great and thank you for your help. Just so I can get my head around it all does this sound the right way of check the PHE out. turn off the mains water, disconnect the loop fill at the tap end, open the valve and in theory if the PHE is leaking across then the boiler pressure will cause it to leak back the other way and come out of the open tap? hope this makes sense. I'm not a heating engineer by trade but have been a time served engineer for 35 years so not afraid of trying to fix the water side of the boiler. Just trying to help my parents say a little money

 

[Johntheo5]

No, these two potential problems are unrelated
If the EV diaphragm is failed then water will eventually fill the air space and the PRV will lift at 3 bar, to check, just depress the schrader valve pin, if you now get water emitting then the diaphragm has failed but even if no water I would suggest keeping the valve pin depressed until the diaphragm is up against the air end. If no water then just pump the air end up to give the same pressure as at the water end was before you commenced the test.
if OK run the system for a few more weeks with the filling hose disconnected.

 

[Hackett123]

No, these two potential problems are unrelated
If the EV diaphragm is failed then water will eventually fill the air space and the PRV will lift at 3 bar, to check, just depress the schrader valve pin, if you now get water emitting then the diaphragm has failed but even if no water I would suggest keeping the valve pin depressed until the diaphragm is up against the air end. If no water then just pump the air end up to give the same pressure as at the water end was before you commenced the test.
if OK run the system for a few more weeks with the filling hose disconnected.

Thank you again. yes sorry what I should have said was if the EV proves to be ok then is there a way of checking the PHE to see if it is leaking across between the primary and secondary. I will disconnect the filling hose tomorrow and leave off for now.

 

[Johntheo5]

Don't really know of any easy method except removing it and pressure testing but hopefully it's not that.

How much water roughly did you get from the schrader valve originally?

 

[Hackett123]

Hard to tell really. I don't think my parents had the boiler service recently so EV pressure may never have been topped up. When I pressed the schrader valve originally and some water (i didn't press it for long) came out I just assumed the EV had gone. Another contributor on here suggested it was still worth pumping up to check and explained about dropping the boiler pressure first, then pumping to 1 bar, and re-pressurising the boiler afterwards. the EV looked to be holding ok. The problem now is that my dad recons he has to drain a couple of litres a day off a radiator to drop the pressure again back to 1 bar. must be coming rom somewhere so my guess is if the fill loop is disconnected at least that rules one thing out.