Potterton Combi 80 DHW Issue

[ttj]

Have a issue with the DHW control on Combi 80 boiler. When we turn on the hot tap the plunger which operates the micro switch deos not seem to move much, have changed the diaphram inside the housing this was not new but an old unit that was given to us by a friend and greased the little plastic stick which connects to the metal head, this seems to move freely enough. The old diaphram was really knackered and in bits. The tap has to be on nearly full before the boiler operates. There has been no improvement or difference in operation since changing the diaphram. Central heating works fine.

Any ideas very welcome.

 

[Beerlover]

You have a rebadged Puma 80 - not a bad boiler though. Anyway my best guess is that the 'new' diaphragm flow switch is also duff or the microswitch is not adjusted properly.

When you turn the tap on and off does the pin move out about a ¼" ? If yes wind the microswitch in until it just touches the piston and try the water again. The red light on the pcb will confirm the switch activation. Make sure it turns off promptly or you will get overheat problems.

If not a new flow swicth and microswitch is not an expensive repair

 

[kevplumb]

View media item 15622
might help

 

[ttj]

Beerlover, Kevplumb

Many thanks for the advice,

The pin only moves about a couple of millimetres nothing like a ¼ inch, would you think it is definately the flow switch that is faulty

 

[Beerlover]

Yes