Potterton Puma 80e - Hot Water, no CH

Puma80e · 1 Nov 2004

Hello,

I have an 8 year old Potterton Puma 80e - and it appears to have decided to have a problem when the CH demands hot water. I can hear the pump running, but the flame does not light to give the hot water. So I have just switched the CH switch to off, pending some assistance hopefully from yourselves!

When I switch on a hot tap, the pump runs and also the flame lights - so I have no problems with hot water. I fear however that if the CH is not working, I am probably likely to have no Hot water soon.

I don\\\'t get a very good flow rate of hot water, but I don\\\'t expect great performance from my combi. It is worth noting that I live in a quite high limescale area, however I have an electronic device which removes limescale from pipes - so hopefully the heat-exchanger is not limed up. I would say over the last few weeks the boiler has \\\'locked-out\\\' on occasion (once every 3-4 days at around 8am).

From other posts here - it sounds like the Hot water Demand Switch could be at fault? What are your thoughts.

Many thanks.

just_thinking · 1 Nov 2004

does burner light during an ignition attempt,pump could be in over run mode so try.heating with boiler cold.

Puma80e · 1 Nov 2004

Burner does not light during ignition attempt when switch CH on. Just noticed only have 0.5 bar pressure - would that have something to do with it???

kevplumb · 1 Nov 2004

so pressure to 1 bar and re post

Magnum · 2 Nov 2004

Got the exact same boiler with the same problem... Pressure is correct at 1 bar, but the central heating locks the boiler out when it comes on.

It's happening once a day now - help!!!

ChrisR · 2 Nov 2004

Magnum it's best if you start a new thread, your problem might be slightly different and it'll get confuddlling.

Puma 80e, are you sure the boiler does not light for CH even if it's cold - well cool anyway. It it heats up and turns off - and stays off, that's not the same as not lighting at all.

There's no risk in using the HW, but DO tell us if it aver fails to light for HW.

HW flow switch is NOT a suspect for these faults.

ChrisR · 2 Nov 2004

Both of you, are you sure the pump's running, it should be near-silent, but you WILL hear the fan. Way to find out is to remove the big screw thingy in the end, while you think it's running, and pull slightly - you'll feel it turning. Or if said thingy comes right out, put a small screwdriver through the hole , which will contact the end of the rotating shaft.

Puma80e · 2 Nov 2004

Haven't got round to pressuring to 1 bar yet - but to answer your question; when cold, and I switch the CH to constant, I hear the (quiet) sound of the pump - but the boiler does not light at all.

I am thinking there must be some kind of trip switch kicked in, as I am sceptical if the boiler will light after I pressure to 1 bar. I'll let you know what happens later when I get home.

Thanks.

ChrisR · 2 Nov 2004

Did you try the reset button

But then it shouldn't have worked for HW. COuld be CH temp semsor - can you measure its resistance? I think everything else would be common to both CH and HW.

If the low pressure light ain't on it ain't low pressure. Again its common.

Puma80e · 2 Nov 2004

I have now pressurised to 1 Bar (and a little bit). Same result, no CH working. I have measured the resistence across the temperature sensor to be 720KOhms, (seemed to fluctuate a little bit +/- 10K Ohms - probably because I had the hot water going a few minutes previous.)

Does this sound okay?

I have a suspected feeling that the CH Overheat Thermostat may be the issue, as a quick inspection on the top of the boiler leads me to beleave a small amount of steam may have come out of the Automatic Air vent - i.e. boiler overheated perhaps at some point? Does this sound reasonable or nonesense.

Many thanks for you help so far. I can feel that this is in reach of being sorted!

(Oh, and I have hit the reset button many times - even though the boiler has not locked out since the CH went wrong.)

kevplumb · 2 Nov 2004

if the overheat stat trips you wont get anything

ChrisR · 2 Nov 2004

Just measured a new temp sensor for a puma - 9kR at room temp and 1kR at near boiling. So oi finks oi woz roight.

Puma80e · 3 Nov 2004

Thanks ChrisR - certainly seems like the temp sensor needs replacing. I will see if I can get one ordered today.

I'll let you know if this is the problem when I have it replaced.

Thanks again.

ChrisR · 3 Nov 2004

COUld have sent you one for a tenner inc p&p. Never mind, measure your new one and see if mine match!

If I'd had brain in gear I'd have suggested you compare it withthe HW one, which is the same part.

kevplumb · 3 Nov 2004

arkright
behave

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Potterton Puma 80e - Hot Water, no CH

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