hello can you help modena 102

[leakstop]

hi all i got a modena 105 runs ok in dhw.
but will only run for 20sec in ch.

boiler sounds like it steaming in ch and then locks out
if i then run the hot tape it spits and steams then run cold for about 15sec then boiler runs ok in dhw .
back to heating runs sounds like its steaming and lock out

thanks

 

[Millsy 82]

You need a GSR as you have a circulation problem.

When did you last use the heating?

 

[Bubblecraft]

Hi & welcome!

 

[leakstop]

4 months ago the landlord had it running
got to the job this morning ch pressure gauge was rising up then blowing off at prv.
so fitted new expansion vessel. boiler run for about 15mins all good then stopped and started steaming.
sorry whats a GSR.

THANKS
and hello Bubblecraft and millsy 82

 

[Dotty]

Hello Leakstop and welcome. A gsr is a Gassafe registered engineer. Because of boilers being what they are it's illegal for non competent people to work on boilers. This actually includes taking the casing off because the seals could be damaged. Strictly speaking, unless it was an external one, changing the expansion vessel was illegal. Whereabouts are you mate?