Puma 100E CH too hot and outside timer

[Ollie_joe]

Have been experiencing problems with my Puma 100. The CH has been turning on when its not supposed to and then getting unbearably hot. Not the best problem to have given the current weather we are having? The problem tends to occur after using the hot water.

Does anyone have any suggestions as to what might the problem and how to go about fixing?

Many thanks

Ollie

 

[bengasman]

Has any work been done on boiler, timer, or roomstat?

 

[Ollie_joe]

New PCB was installed over xmas. It was also serviced shortly after. No work has been done on timer or roomstat in the 5 years we've been living with it.

Thanks

 

[petit_pablo]

Run the hot tap and see whether the boiler goes off as soon as you turn hot tap off. If it doesnt the microswitch is sticking, common fault.

Also the diverter or wax capsule is possibly faulty. To test this allow system to cool down. Run hot tap and feel CH flow pipe, i think its 2nd from right, it shouldnt get progressively hotter as the hw heats up

 

[Ollie_joe]

thanks for the info. I do seem to remeber the wax diverter valve/capsule being replaced a couple of years ago. I would like to think they would not need replacing again for a little longer.

I'll check the micro switch first.

thanks again

 

[Ollie_joe]

Have replaced the microswitch, but sadly no joy. If anything the problem has got worse. Everytime the HW is used the CH becomes extremely hot. Both the HW and CH dials have been turned down.

Is it possible I have installed the microswitch incorrectly? not screwed in tight enough perhaps...?

I have carried out the test suggested in the previous post and the CH pipe does get very hot. Does this mean the problem is with the wax capsule?

Any other suggestions as to the what cause of the problem might be....

Cheers

 

[Ollie_joe]

Another observation is that the pilot light keep going out and eveytime I use the HW for showers, kitchen sink etc. Ihave to re-light the pilot before taking it off of standby.

 

[DP]

Your boiler does not have a pilot light. 100E is fully electronic ignition i.e. it lights the burner on demand.

The microswitch atop the HW demand manifold is operating. Take one of the wires and see if boiler shuts down. 240 volts caution applies.

Possible this unit needs to be serviced.

Common problem where boilers are 'serviced' but working parts rarely see the service they merit. Usually it is a spring clean with a duster, nothing else. Service should be what the manual asks for.

 

[Agile]

It certainly sounds as if the DHW switch is sticking on after DHW demand.

You can easily see that by watching the red light on the pCB. It should go off immediately the DHW demand has ceased.

If so then another problem you may have is a failed sensor. With the boiler totally cold you need to measure the resistance of each sensor with the lead disconnected of course!

Tony

 

[Ollie_joe]

Thanks for the replies.
The red light on the PCB does stay on constantly once the HW has been used.

Sorry, I meant the ignition light keeps going out, sometimes while heating the HW as it did this morning, but more often once the boiler has been elft idol for some time.

IF the porblem is the DHW switch I take it that is something that can be replaced or will it need further work carried out. Should a service put all these problems right. As i mentioned the boiler was only serviced as recently as 6 months ago

 

[Ollie_joe]

Oh no.
Boiler just went bezerk. Started make a loud sort of overheating noise. That flames in the ignition window looked alot more ferociuos thatn usual. at that point i switch off at thje mains. It then sounded like there was some kind of leak. It has since calmed down and it appears the leak came from the auto air vent.
Was just about to replace the DHW flow switch.
Although I suspect the problem to run deeper than a faulty microswitch and flowswitch.

Any ideas?

 

[Agile]

The problem is probably only the microswitch.

Its not the switch but the adjustment or the shaft is seized.

I doubt that any parts will be needed.

The "too hot" may be another problem but might just be the boiler settings.

Tony

 

[Ollie_joe]

problem finally solved.
Replaced the dhw flow switch. Was a little tricky to get the hang of but managed to follow the service manual instructions I found on the web.
Thanks to everyone who helped out. Hopefully this thread will benefit someone else in the future.

 

[Agile]

Have replaced the microswitch, but sadly no joy.

Cheers

Thats interesting!


You had already replaced it before!

Tony

 

[Ollie_joe]

that was the microswitch i replaced before. this time i replaced the dhw flowswitch. apart from the auto air vent leaking water. It works fine. I have started a new post for that problem.

cheers.