Rafal Kaczynski
Hi Julia Yes Powermax boilers can cause a lot of problems and are very difficult to service. I will try to respond and give you advice as much as my knowledge abou fault is. 1) Central heating failure while hot water continues to work as normal. The immediate cause is the central heating pump not running. The two common causes of this are timer/programmer failure and a seized or failed pump. The seized pump can be diagnosed by measuring for mains voltage on the input terminals. If voltage is present and the pump is not spinning, the pump needs freeing or replacing. If voltage is NOT present at the pump, check the programmer. This is notoriously unreliable. Testing for mains voltage on the output terminal of the central heating channel when heating is selected. No voltage means programmer failure. This is quite a perverse fault as it often occurs immediately the electricity supply is restored after being turned OFF for servicing or another repair. This leads to the technician (or the customer!) wondering if they may have misdiagnosed the original fault or caused the programmer failure by doing something wrong... but this is not normally the case. The failed programmer has to be replaced. New programmers are expensive but if you are competent with electricity and capable of diagnosing and replacing your own programmer there is a cheaper alternative. 2) Hot water runs hot initially then cools down. Most commonly caused by a failed thermostatic blender valve. A new valve fixes the problem. Less commonly the cause can be water scale. If the Powermax has an external plate heat exchanger this can be replaced quite easily and hot water is immediately restored. Many Powermax boilers have an internal domestic water heat exchanger and chemical descaling will be necessary. Not especially difficult but time-consuming and invasive. Involves bringing chemicals, a descaling pump, hoses etc into your house. I hope this will help Best regards Rafal
