Had this before with a Baxi

[PEDANTICVINDICTIVEMAN]

And never got to the bottom of it-

This time it's an Alpha 240p.

Gas rate fine, modulates fine, new DHW sensor even though ohms ok on old one but changed it anyway, flushed out plated exchanger twice with drain cleaner, it's def clean, diverter not passing, but at 9lts a min only getting approx 44deg at the tap, it's only feet away so not losing in distance, cold coming in at approx 12deg so temp rise only approx 32deg.

Did find why rads a ******* to heat, CH filter badly blocked, I'm wondering if the main gas to water exchanger is dirty ?

 

[muggles]

According to the manual it only passed 9.5l/min @ 35ºC rise when it was shiny and new all those years ago, it's not lost an awful lot of performance...you may just be expecting too much of an oldish boiler, depends really how much your custard wants to spend attempting to extract that extra 3º and half a litre a minute while you strip it down more and more...

 

[PEDANTICVINDICTIVEMAN]

Thanks for the reply, I didn't have any MI's to look at so wasn't sure whether it was rated at 35 or 40 deg, thanks.

 

[namsag]

Auto bypass at back of divertor probably stuck partially open and robbing the water going to the plate . Boiler circuit heating up and cutting off quicker than it should

 

[PEDANTICVINDICTIVEMAN]

Got some MI's on it now, is the byepass valve "cleanable" or do I need to replace diverter valve ?