glow-worm G.C. No. 41-047-71 38hxi heat exchanger

[Simon F]

I replaced the pump on this boiler a few months back.
It was cutting out, flow a lot hotter than return,
radiators not performing well, figured a circulation issue.
The new pump did help no longer going to lock out,
but there is still an issue,
fires up temp rises about 10 degrees quite quickly then burner stops / starts.
this keeps happening and gradually things start to warm up,
flow is a lot hotter than return.

So I am thinking the heat exchanger is scaled up, boiler is est 10+ years old??
although the system is very clean.

could it be something else?

if it is the heat exchanger they are priced 400-600 depending which supplier.
doesn't look an easy swap, is it recommend new boiler,
or is there an option to dose with scale remover and flush?

 

[Leo21]

Could be like this, looked clean this one.

 

[smtplumbing]

Simon f not try to take work away from you at this point and if the customer wants it done call glowworm out as all your going to do is give Yourself hassle