Our Puma80 boiler developed a DHW problem last week. It heats water up but then only maintains a lukewarm flow, which is not a lot of fun in the shower! So far, changed the DHW temp sensor, DHW limit thermostat and recently had a plumber out who changed the diverter valve. Nothing has worked, CH is fine but DHW still lukewarm. Potterton response was we can arrange an engineer to visit. Thinking about getting a new boiler but wondering if there is something obvious that we've missed? Any ideas from anyone would be most appreciated!
Potterton Puma80 DHW problem
- Thread starter Spanners
- Start date
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Are you in a very hard water area? Limescale wouldn't go critical in a week I know, but ?
Pump could be on a go slow. Does the boiler cycle on and off (or does a puma go hi-lo?) when you open bath hot tap fully?
Pump could be on a go slow. Does the boiler cycle on and off (or does a puma go hi-lo?) when you open bath hot tap fully?
Cheers for your suggestions.
Bripl - gas pressure appears fine as boiler happily heats the whole house nicely, but I'm not an expert so how would I check this?
ChrisR - I'm in a hard water area. I added a load of Fernox products to the CH a couple of months ago but how would I descale the DHW pipes? I assume these are on a separate circuit to the CH as we weren't washing up in fernox stuff, so how do I get to the DHW circuit? I've read about powerflushes but is there anything simple like adding a descaling solution as you would with a kettle/iron?
Bripl - gas pressure appears fine as boiler happily heats the whole house nicely, but I'm not an expert so how would I check this?
ChrisR - I'm in a hard water area. I added a load of Fernox products to the CH a couple of months ago but how would I descale the DHW pipes? I assume these are on a separate circuit to the CH as we weren't washing up in fernox stuff, so how do I get to the DHW circuit? I've read about powerflushes but is there anything simple like adding a descaling solution as you would with a kettle/iron?
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Gas - Turn HW taps on full and time the flow at the gas meter. If it's imperial time for 1 cu ft (one rev of the dial usually), if metric measure flow in cu metres in 2 minutes. COme backa nd we'll judge.
I'd still want answers to the other q's I asked.
Descaling your tap water side pipes needs pump etc you won't have. It isn't like powerflushing.
I'd still want answers to the other q's I asked.
Descaling your tap water side pipes needs pump etc you won't have. It isn't like powerflushing.
you sure about the time 
78 secs gives 14.07 kw
well down
78 secs gives 14.07 kw
well down
You may be able to tell by careful listening or by watching the dial on the meter.
If it's on-off, it would be on longer when first turned on so give it half a minute start.
If not on-off then its gas valve dept(corgi)
If it IS it's either
Sensors
pcb
sludge/scale
Slow pump.
Which I'd diagnose by measurng temps, testing pump, measuring sensors. May then try swapping pcb. (have plenty!)
And here was I looking forward to a nice quiet Sunday watching the bike racing with a few beers... no seriously, cheers for all your help.
Here we go:
Timing is correct. Tested again with bath hot tap on full and 1min 18s to do one full turn of dial. Should I have all taps on? Or does it not matter?
On off malarkey. Gave boiler 30s head start and couldn't detect any change to how anything was running. Checked dial and needle went round at a consistent rate. Gas valve maybe, any ideas as to costs for replacing these? Sensors are all new. Pump was changed and system drained by a plumber Feb02 at a cost of £481! Then new PCB in Mar02 at a cost of £350! That was not funny and seriously damaged my finances.
Can't test whether pipes get hot as had heating on most of day so all pipes too hot to play with! Will try this tomorrow once heating has been off for the day. Will be well unhappy if any problems in diverter valve area as forked out £200 for a new one last Monday.
We're thinking off getting a new non Potterton boiler now and sticking this one where the sun doesn't shine.
Here we go:
Timing is correct. Tested again with bath hot tap on full and 1min 18s to do one full turn of dial. Should I have all taps on? Or does it not matter?
On off malarkey. Gave boiler 30s head start and couldn't detect any change to how anything was running. Checked dial and needle went round at a consistent rate. Gas valve maybe, any ideas as to costs for replacing these? Sensors are all new. Pump was changed and system drained by a plumber Feb02 at a cost of £481! Then new PCB in Mar02 at a cost of £350! That was not funny and seriously damaged my finances.
Can't test whether pipes get hot as had heating on most of day so all pipes too hot to play with! Will try this tomorrow once heating has been off for the day. Will be well unhappy if any problems in diverter valve area as forked out £200 for a new one last Monday.
We're thinking off getting a new non Potterton boiler now and sticking this one where the sun doesn't shine.
is the dial 1 cu ft or 2
You've been stung a bit with the bits you've had. I just hope the diverter valve change was the whole thing and not just the capsule on the front end of it he changed. Any idea?
Hmm, Presumably if you turn the tap down to half flow it gets hot?
New gas valve likely to be thick end of £200.
But then you'll have changed most all of the bits on the boiler.
Where are you? One of us might be local and take pity.
Hmm, Presumably if you turn the tap down to half flow it gets hot?
New gas valve likely to be thick end of £200.
But then you'll have changed most all of the bits on the boiler.
Where are you? One of us might be local and take pity.
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