Potterton Puma 100e - Overheat & Lockout

[xdee]

Hi There,

I have read several messages on this forum relating to a similar problem that I have but have yet to find a definitive answer.

I inherited a Puma 100e after moving into my property a couple of years ago - it was installed in 2000.

I have the following problems:

1) After using hot water, the flame light does not go out and the boiler overheats and "blows". On some (not all) occasions this causes a "Lockout". This happens frequently AFTER using hot water through a shower or tap (normally for at least 20-30 seconds but can be longer).

2) My central heating does not work properly at all. The heating upstairs comes on luke warm after 90mins but the ground floor radiators are freezing. The radiators were balanced not long ago.

I can think of no particular events that have caused this to happen. I can tell you three things that have been changed while this problem has been occurring:

1) The descaler burst. (i think thats what its called - purplish rectangular "thing" that connects to pipes and is supposed to descale the water?). This has not been replaced - a pipe was simply used to connect everything back up.

2) The electronic timer was not working for the heating. This was replaced by pottertons own mechanical timer, which seems to work.

3) The valves on virtually all the radiators were changed as they were quite old.

The radiators have been bled.

I have noticed that if you put a cold water tap on immediately after using the hot water then the boiler is less likely to blow.

Can anybody provide a list of solutions?????

Thanks in advance - i'm ready to try anything as i need the heating before the winter really kicks in!

xdee

MOD

please see item 17

post has been split

 

[DarkInferno]

flowswitch is sticking/blocked.

 

[meldrew's_mate]

I agree the flow switch is causing the overheat.

2) My central heating does not work properly at all. The heating upstairs comes on luke warm after 90mins but the ground floor radiators are freezing.

First use of the 'f' word this season. The puma has a wax thermostat based diverter which often causes problems and may be the cause of your heating woes.

 

[bengasman]

The Pumas have indeed a really problematic diverter valve, unreliable and expensive. You can get repair kits though that save a lot of money. It sounds like the flow switch or the valve are faulty. This is often caused by corrosion or limescale. If your radiators downstairs are cold you could well need a good flush. If so, a powerflush is te only thing that will get all dirt out. Try closing all the upstairs radiators and see if any downstairs heat up at all. Feel the bottom of the radiator and if the middle is colder than the sides, a powerflush is the answer. If you replace the valve and leave the dirt in, it will sooner or later fail again. Probably sooner.