PUMA 100e - SWITCHING OFF WHEN DRAWING HW

[wildweasel]

I hope you can help.

I've I potterton puma 100e boiler that I'm having problems with, symptons are:

Draw water either from the tap or a shower and the boilder makes a loud noise that sounds like a jet engine reversing, followed by a release of air and a click as the pilot light goes out. I've watched the temperature guage during this even and it rises by about .5bar returning to normal just after the light goes out.

The central heating seems to work fine although I don't have the temperature much higher than 20.

I had a new fan fitted recently after the last one packed in. Following this the boiler worked fine for a short while and stopped overheating, however now it happens every time water is draw and is getting increasing frequent.

It has been mentioned to me that scale maybe the cause and I do live in a very hard water area.

Any ideas?

Thanks
Colin

 

[Vic Spanner]

hw flowswitch fault...Do a search on (puma flowswitch) here has been discussed many,many,many,many times

 

[Agile]

What Poxi is describing is the cause of your symptom but only if the boiler does that immediately AFTER you turn off the hot water!

If it does it WHILE you are using the hot water then it will be another cause.

Tony

 

[wildweasel]

What Poxi is describing is the cause of your symptom but only if the boiler does that immediately AFTER you turn off the hot water!

If it does it WHILE you are using the hot water then it will be another cause.

Tony

Thanks Tony.

For example you could take a 10min shower and it works fine. The boiler makes the noise and 'trip' once the water has been switched off.

It re-lights immediately after.

Colin

 

[wildweasel]

I can be a little clearer about the problem, so I hope someone can help.

If the CH is off, drawing HW works fine and the boiler does not overheat and switch off.

If the CH is on, when drawing HW the boiler works ok although it does take a little while to heat. Once you stop drawing HW, the red light on the modulator board goes out, however the boiler flame seems to rise until the boiler overheats and switches off. Once the boiler is re-lit the CH fires up and the boiler operates as normal until the process is repeated.

The flow valve and switch seem to function ok given that the red light operates in unison with the HW being drawn. Also the fan seems to be working ok.

Please please can anyone help?

Thanks
Colin

 

[Agile]

I cannot immediately offer any exact diagnosis in that case as the DHW switch is opening if the red light goes out.

However if the burner is staying on then it would indicate an unusual PCB fault or a gas valve sticking on.

Since the latter is potentially quite serious, I would advise its checked by a competent CORGI asap !

Tony

 

[wildweasel]

Still having problems and reaching a point of desperation since I can't get hold of my plumber.

I still have the same symptoms as above except that now when the CH is on it fires up to heat the radiators for about 20 seconds and then switches off as if its reached temperature. The it fires up again and continues, sometimes it runs for longer than 30 seconds, i.e. for a few minutes before switching off. Does not appear to be overheating when operating only the CH.

Please can someone advise?

 

[Slugbabydotcom]

I've got a feeling that your fan might be stiffening up.
With the power off does it feel stiffish to turn? It should spin freely.
Try a drop of oil on the bearings

 

[wildweasel]

I've got a feeling that your fan might be stiffening up.
With the power off does it feel stiffish to turn? It should spin freely.
Try a drop of oil on the bearings

Fan was changes very recently since the old one packed up. It is interesting you mention the fan since the guy that fitted it was a bit dodgy and never had a PUMA 100 fan so fitted one off a PUMA 80. I remember reading something about the difference between the 80/100 fan. Would that add up?

 

[Slugbabydotcom]

Logic dictates that the 100 should run faster than the 80 fan

The part numbers are different
Part number/GC number
929502 379 343

929501 379 342


I would say we are on to something. Hopefully a potterton engineer will be on later to confirm this.

The part is either right or it isnt, and yours isnt so this has to be ruled out first

 

[ChrisR]

Puma 100 fan is beefier - although it's cheaper.

Sludge in the heat exchanger, sluggish(slow or sludgy) pumps and lazy diverter valves all conspire to make old pumas overheat.

 

[Agile]

Its normal for Pumas to fire up for a few seconds every minute or two when starting CH after DHW has been used.

This is a result of the odd diverter they use but after a few minutes the burner will stay on and heat the radiators.

It sounds as if the CH sensor may be faulty and keeping the burner on. Have you checked the resistance? Should be 10 K cold reducing to about 2 K hot.

Tony