Potterton performa 28 combi boiler

[londondave]

Hi all,

potterton performa 28. Just started job. Boiler is not generating enough heat for the bath water. I notice the scale goes upto 80 degrees on the front then the boiler flame goes out and switches off. It seems like heat isnt getting out of the boiler circuit into the DHW coil.

About to check for blockages, but any advice would be greatly appreciated ! thanks Davce

 

[Zorro]

how old is the unite?

 

[londondave]

this unit is 7 years old.

Am suspected a blockage in the heat exchanger. theres a nut that looks like it could be an inline filter so I am going to check it out to see if it is a blocked filter.

Gas pressure 18mb at inlet

 

[Zorro]

maybe heatexchanger has scaled up? ive had that with a halstead

 

[Billy Bob Bob]

check dhw thermistor,diverter valve for dumping down or sticking and the plate heat exchanger

 

[wnjswozo]

also gas rate it ,to make sure no issues with gas pipe sizing

 

[londondave]

Took out the heat exchanger found it to be full of black ferrous bits from the radiators. Tested sensor with green wires and found it to be 9.9 ohms at room temp.

Bought new sensor (also 9.9 ohms so didnt fit) and new heat exchanger.

Changed heat exchanger and boiler now runs fine. Very hot water and no need for gas to switch on and off due to first circuit over heating like it did before.

Thanks for advice.

Dave