Puma 80 pilot goes out

[radio_engineer]

I have had no end of problems with my Puma 80 recently. First water pump failed, and I replaced the head. Boiler was fine for more than a week after but then fan failed. After the fan was replaced, I decided to add some sludge cleaning chemicals as during pump change week earlier I have noticed corroded bits in CH water. I also did try to flush system using mains pressure as explained on some posts here, fed via filling loop and released on drain off point. I was careful not to have more than 2.5 bar pressure.

Once boiler was fired up it started having problems with pilot flame going out after 3o minutes or so on CH. Also radiators appear to take bit more time to get hot but they do get hot. I have reduced flow through bypass valve to improve flow in rads and it helped radiators getting hot but pilot light still goes out. What could be problem here., I have searched this forum but many examples do not make much sense to me, especially this series of faults.

Is it possible I had done something to disturb pilot flame (it is fine all time if boiler is on standby mode only problem on CH mode) I suspect some sort of overheat protection kicks in. I have removed wires from DHW temp sensor and DHW limit sensors and have put them back on. Could something be disturbed by flushing or stuck after sludge got disturbed?

Other than pilot flame it all looks fine, no leaking hot taps, pump works fine set on 3 as advised on this forum. I believe I have purged air from boiler and all radiators, AAir Vent cap/screw is loose. Only difference is slight noise as CHW is pumped it appears to be some dirt in there.

Any help please. sorry for long description.

 

[corgiman]

Is the water circulating cos the old wax diverter valves on the pumas are buggers for failing?

 

[radio_engineer]

how could I check if Puma diverter valve failed? would this result in pilot going off

thanks for advice

 

[corgiman]

Could do cos if you turn the heating on and the valve dont open the boiler will over heat and whack off the pilot

look under the boiler you will see on the right hand side two 22mm diameter pipes with isolators on them, one with a red top and the other with a blue one, turn on boiler and central heating and put your hand on the pipe with the red top, be careful cos the valve is liable to open and send really really hot water down that pipe all of a sudden (if it is workin) if not the its the valve

Edited by me cause I didnt get a tick from softus lol

 

[Softus]

...two 22mm diameter pumpms with isolators on them...

Did you mean pipes? Not being critical, just didn't want the poster to go looking for two pumps...

edited because my bold tag was missing

 

[corgiman]

fair enuff softus I did means pipes

and it is 1 am!!! give a hard working chap a break

 

[Softus]

8)

 

[corgiman]

all right all right dont rub it in

do you think radio has left us am only staying up to help him lol

 

[Softus]

He's still showing as logged on, but doing what we just don't know...

 

[corgiman]

hopfully not getting third degree burns by following my advice

 

[radio_engineer]

Thanks,

I presume you mean two 22m pipes for CH flow with valves just below boiler casing then these two do get worm as the boiler is turned on. The boiler works for 30 minutes and radiators do get hot.

 

[corgiman]

mmm not the diveter valve then.


possible the over heat stat is fault, not much i can say about that as defo CORGI job

sorry radio

 

[radio_engineer]

Can I test this before I get CORGI man out to replace the overheat termostat, this is third failure with boiler in less than 3 weeks !!! I may skip the lot!

 

[ChrisR]

You have found that SOME heat goes to the ch in ch mode, but how much...

If you follow the pipework in the boiler you can work out which pipe should NOT get hot in ch mode. It goes up from the diverter valve to the heat exchanger. See if that gets hot.

Could also be a simple pilot starvation thing - pilot reduces when main burners are on and thermcouple cools. Hard to see anything on a puma, and all different with the cover off so not relevant. Often need new thermocouples and sometimes pilot assemblies cos they don't come apart for cleaning. All corgi stuff though. You would expect it to happen on HW too.

 

[radio_engineer]

Thanks ChrisR,

There are two pipes going up from diverter valve , one is 22mm and is at the back end of valve and goes up and to the right side of boiler, it follows the pipe where the pump is on. Another pipe going up is 15mm and goes up from the front of diverter valve and bends to the left side of boiler.

Presumably only 22mm pipe should get hot in CH mode only is this correct?