• Potterton Powermax Boiler

    The Potterton Powermax boiler for some reason seems to frighten gas safe engineers away.

    As soon as the name Powermax is mentioned no one wants to know.

    But why? The Powermax boiler was made by range before Potterton took the boiler over.

    The boiler was based on an excellent concept it’s a shame the implementation was so flawed. 

    The idea for the Powermax boiler was conceived back in the days when mains pressure hot water cylinders.

    Otherwise known as unvented hot water cylinders were not permitted under the Building Regulations.

    The only way to get high-performance showers was by installing pumps.

    The Powermax boiler idea was to combine a boiler and hot water cylinder into one unit.

     An integrated device that was capable of delivering both central heating and mains high-pressure hot water.

    This was using the ‘thermal store’ principle, so high-pressure showers could be fitted in flats especially without the use of those expensive and noisy pumps. 

    So how did the Powermax boiler work?

    A tank full of water was heated not by a separate gas boiler, but by an integrated gas burner.

    That squirts flames down several tubes running straight through the water tank. 

    The tubes heated the thermal stored water, which was then pumped or circulated the radiators for the central heating side; the best part was the way the mains pressure hot water was produced.

    Cold mains water was fed into a coil of tube suspended inside the heated water tank, and the cold water was heated through the wall of the coiled pipe in real-time as it flowed through the coil on the way to your hot tap or the shower. 

    Mains pressure hot water at high flow rates with no pump, in full compliance with the Building Regulations of the day! Great. 

    So Why Do Service Engineers Walk Away?

    The Powermax boiler suffered many problems; one of the problems was with the twin-pipe flue. 

    The boilers were so efficient that when they had long flues fitted they would start to condense, and as we know condense is acidic.

     With the flues being made from aluminium, they would start to corrode and release Carbon monoxide. 

    Another problem is the gas valve and the burner gasket. 

    The clever new type of gas valve does not take kindly to being fiddled with by service engineers without the use of a flue gas analyzer to measure the effect of the adjustments being made.

    Carbon monoxide is produced in large quantities. 

    This problem perversely combines with the fact that the main burner gasket is prone to leakage. 

    Always make sure that a new gasket is always used every time the burner is removed for servicing, this is the advice from Potterton technical support

    Not many service engineers carry these burner gaskets in their van. 

    The engineers who see no point in replacing the burner gasket are possibly the same engineers who do not have use of a flue gas analyzer.

    This has to lead to CO from poor combustion leaking from the burner gasket and has lead to the deaths of several users of Range Powermax boilers in the past.

    This is one reason for the bad reputation of the Powermax boiler and the reluctance of service engineers to work on them. 

    If you come across a Powermax boiler on your travels, don’t be put off by them; you can download all the installation and serving instruction from the Internet.

    Just type into Google, Powermax boiler and the model number, and you will find all the information you need. 

    Potterton has since updated the Powermax boiler, today’s version is the HE model,

    HE being the Highly Efficient condensing version. 

    The new version on the Powermax boiler is a boiler and cylinder joined together as one. 

    High-pressure hot water and pressurized central heating system

    In general, the Powermax boiler is not as bad as people think.

    Parts can be very expensive should you need them, but then that’s normal for something different.