boiler over pressurising

[muso58]

Hi all odd one here.
Firebird enviromax boiler . was gaining pressure up tp 3 bar . to point where safety valve was opening.
Fitted new expansion vessel 12 litre same as original.
Still happening . dropped pressure back to 1bar via safety valve still keeps rising
Thought maybe fill point valve was defective so ive even clamped off flexi hose from fill point outlet.
Any ideas totally mystified .

 

[CBW]

Was the communication pipe up to the vessel checked for a blockage?

 

[muso58]

Hi yes did that this morning

 

[CBW]

Was the new vessel checked for correct charge? Is it rising without use?

 

[muso58]

Hi charged to 1bar before fitting. i wonder if it could be heat exchanger ?

 

[CBW]

Hi charged to 1bar before fitting. i wonder if it could be heat exchanger ?

Could be the plate heat exchanger if it has one. Isolate the cold into the boiler and see if it stops rising

 

[muso58]

Ive isolated heat exchanger .it has a valve just before exchanger on water inlet .
Had heating on for 2 hours and its steady at 1.2 bar .I think its heat exchanger !
live and learn .
Thanks for all the replies

 

[muso58]

heads up. it was plate heat exchanger.
symptoms sounded like expansion vessel . live and learn