Potterton Puma Combination Boiler

[Terry]

Hi Guys appreciate some advice.
My father has a 12 year old potterton Puma combination boiler on a support contract, the attending engineer reports that the heat exchanger is scaled/sludged up and requires descaling/replacement.

Boiler works fine for domestic hot water operation, but it struggles to heat up the central heating circuit.
Flow pipe from boiler gets hot but there appears little flow, so boiler cycles.
Attending engineer says pump is ok?

My questions are as follows:
1. Does this diagnosis seem ok, I would have thought the HW circuit would sludge up before the CH circuit
2. Is a descale of the heat exchanger viable on a boiler of this age, would it be better to change the boiler
3. Is there any way of testing the pump for flow, not just feel that its running
4. If we have to change the boiler any preferred brands

thanks

 

[GrahamM]

Sticking wax capsule divertor been ruled out? Very common issue on these.

 

[P J F PLUMBING]

It depends what you want to spend the boiler won't be as efficient as it could be you could spend ££ on fixing it but something else could break in a few months but it could be a descale ect and its fixed

 

[pobsdad]

Make sure there are no hot taps dripping.This will cool the wax stat and stop the heating working.

 

[Terry]

Another plumber came round and changed pump, everything appears ok now.
Who to believe!

 

[AWheating]

pump on the puma is pants and is a common fault. Had alot of them fail even when new.

 

[vern]

pump on the puma is pants and is a common fault. Had alot of them fail even when new.

Yep good old Myson CP61, replace with CP63, impellers also shear off, and spindle goes round fast so you think pump is ok, when the impeller is not even turning!