Potterton Puma 100e not firing up

5 Nov 2009
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United Kingdom
Hi, wonder if anyone can help I have a Potterton Puma 100e which is a few years old and has always given problems. My latest is that I cant obtain any hot water or central heating. When a hot tap is opened a restricted flow is heard through the boiler but isn't followed by the boiler firing. I followed the fault flow chart which suggests faulty fan but the fan can be heard running when a call for c/h is made. I have changed the DHW flow switch and micro switch but still no joy
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Little point in changing random parts in the hope it will solve the problem.
If there is neither ch,nor dhw, and you have verified that the gas is on, the boiler has power, and the pressure is around 1 bar, it is almost certainly a fault outside the diy sphere.
Hi Thanks for the replies, the mains light is on and the red light on the electronics board also lights when a hot tap is opened. All the voltages are correct as referred to in the fault finding chart and the relays open and close when boiler is switched from standby to on. But the fan will only run with a call to c/h and the pump is running but wont fire up. Any thoughts would be appreciated. I have also bench tested the fan and it definatley works.
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try checking air pressure switch and tubes going to it, sometimes you get a crack in the tube, which will stop boiler firing.
Removing the fan and working on an APS is the province of a registered gas engineer and we should not be gining DIY advice on gas work.

Could be a faulty main PCB but I would wonder if the DHW flow switch is correctly fitted/connected. Also worth checking the sensor resistances.

Best to call an RGI !


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