potterton puma 100e: No heating

[Boiler32]

Hello

Hope you can help.

Hot water is working but central heating only comes on sporadically (usually for 20 minutes then switches itself on and off but the radiators go cold).

British Gas and my plumber have tried the following without success:

1) Replaced divertor and pump. Did not work suggested power flush
2) Powerflush. Did not work
3) Replaced divertor again and PCB. Did not work.
4) Discovered that turning of hot water tap on boiler allowed the heating to work perfectly.
5) Discovered that isolating hot water to shower (turning off valve) allowed heating to work perfectly.
6) Some limescale on shower thermostat cartridge indicating a leak. No other leaks visible. Cartridge replaced, heating still does not work if hot water valves are on.

Hope this makes sense. Does anyone have any suggestions as to what the problem might be - BG and an independent plumber/heating engineer have been at least 10 times in the last couple of months and are stumped. We have a Potterton Puma 100e boiler and a shower from Bathstore. The pressure on the boiler is fine.

Many thanks

 

[sooey]

There's a leak on your hot water somewhere, if isolating the shower allows the boiler to work properly then that's where it has to be. Also there is an adjustment on the flow switch on these which should be checked.

 

[Boiler32]

Thanks for the reply. How do I go about checking the adjustment on the flow switch?

 

[sooey]

Have you got the instructions, there's a diagram in there. It should be 5-6 mm and has a locknut to slacken for adjustment in and out.

 

[Boiler32]

Thanks - I will check that.

 

[sooey]

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