Potterton Puma 80e - DHW going hot/cold/hot/cold
- Thread starter Crazi
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i would say most likely to be the temp thermistor but could also be down to the fact that the h/exch is scaled up whats the flow like through boiler ?
Crazi, I think you need to be more precise about hot water flow rate. Open hot tap fully, time how long it takes to fill a container of known capacity (e.g. 1 litre bottle, 5 litre bucket, etc.). Then post these figures, from which we can calculate flow in litres/minute.
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Just been having a look - when the heating is on and we request DHW - the water remains hot. The machine fires up and everything works fine. However as soon as we switch the CH off the water goes back to hot/cold/hot/cold.
ie.. when requesting water in "Winter" mode the temperature seems to stay constant but in "Summer" mode it goes hot, cold, hot cold.....
ie.. when requesting water in "Winter" mode the temperature seems to stay constant but in "Summer" mode it goes hot, cold, hot cold.....
Chris - So my flow rate is at best crap 
.... Could this be making the thermostat act wonky? ie.. it's not switching back on fast enough because the flow rate is way too low so it's sensing the temperature difference too late?
I forgot to mention that I replaced the Limiter last year because pressure seemed to be dropping and this didn't help. Could the flow switch be faulty and making the limiter stop the flow? or am I being a silly female ...lol
Gaz - you are a local Potterton engineer. How much to get someone to service/clean the heat exchanger and how do they clean it properly so I can watch and make sure they are doing it? I am worried about paying for a service and the guy just takes the usual meter measurements, leaves and says "that's all normal"....
PS... Someone has mentioned the wax capsule head and wax capsule to me - What do they do? Looking at the diagram they look like they are just switching the diverter CH so i don't think they have much to do at all with my DHW pressure?
Appreciate you guys patience
.... Could this be making the thermostat act wonky? ie.. it's not switching back on fast enough because the flow rate is way too low so it's sensing the temperature difference too late?I forgot to mention that I replaced the Limiter last year because pressure seemed to be dropping and this didn't help. Could the flow switch be faulty and making the limiter stop the flow? or am I being a silly female
...lolGaz - you are a local Potterton engineer. How much to get someone to service/clean the heat exchanger and how do they clean it properly so I can watch and make sure they are doing it? I am worried about paying for a service and the guy just takes the usual meter measurements, leaves and says "that's all normal"....
PS... Someone has mentioned the wax capsule head and wax capsule to me - What do they do? Looking at the diagram they look like they are just switching the diverter CH so i don't think they have much to do at all with my DHW pressure?
Appreciate you guys patience
I'm not an expert on Potterton boilers (unlike Gazthepottertonengineer) but I'd say the very low flow rate was the problem. Probably just at the threshold for operating the flow switch. When water heats up, flow decreases (not sure why, but it always seams to!), then flow switch goes to off, then water runs cold, flow increases again, flow switch operates, etc.etc.
The question is "what is restricting the flow?". Could well be scaled up secondary (DHW) heat exchanger as Gaz suggested, but other possibilities should be considered. For example is cold water flow adequate (i.e. more than say 10 litres/min), are isolating valves on boiler fully open, is hot water flow equally poor at all outlets (taps)?
The question is "what is restricting the flow?". Could well be scaled up secondary (DHW) heat exchanger as Gaz suggested, but other possibilities should be considered. For example is cold water flow adequate (i.e. more than say 10 litres/min), are isolating valves on boiler fully open, is hot water flow equally poor at all outlets (taps)?
Cold water pressure is good. We had them check it and I believe it was about 4bar. We get about a litre every 4/5 seconds or so. All inlet valves are fully open and the hot is bad at all hot water taps.
I think from your explanations I have a blockage ... Time for a British Gas engineer I think. Are BG engineers any good?
I think from your explanations I have a blockage
... Time for a British Gas engineer I think. Are BG engineers any good?
I did ask you what was the "limiter" which you replaced and where was it located but it seems my post has been deleted!
My thought is that you are better getting an independent engineer who is familiar with the boiler as the costs are likely to be lower. BG engineers sre not always very good with Pumas and are likely to recommend a new boiler. Potty engineers are likely to be very competent with that model but are likely to be significantly more expensive as I dont think it is a very serious problem.
Tony Glazier
MOD
why should your post have been deleted ??
as you have been asked before Mr glazier pack the snide digs
My thought is that you are better getting an independent engineer who is familiar with the boiler as the costs are likely to be lower. BG engineers sre not always very good with Pumas and are likely to recommend a new boiler. Potty engineers are likely to be very competent with that model but are likely to be significantly more expensive as I dont think it is a very serious problem.
Tony Glazier
MOD
why should your post have been deleted ??
as you have been asked before Mr glazier pack the snide digs
To anonymous Mod,
Kev? he often calls me "Mr Glazier" in such a manner rather than a more friendly "Tony".
Perhaps YOU can tell me why it may have been deleted?
Thats why I dont feel comfortable posting here, unexplained deletions and unfriendly comments by anonymous moderators.
Tony
MOD
it wasnt deleted
you pressed the wrong button
as in it was never posted
as you have been informed on more than one occasion if you dont feel comfortable posting on here
DONT
Kev? he often calls me "Mr Glazier" in such a manner rather than a more friendly "Tony".
Perhaps YOU can tell me why it may have been deleted?
Thats why I dont feel comfortable posting here, unexplained deletions and unfriendly comments by anonymous moderators.
Tony
MOD
it wasnt deleted
you pressed the wrong button
as in it was never posted
as you have been informed on more than one occasion if you dont feel comfortable posting on here
DONT
The limiter is located at the output of the hot water. Also connected to the flow switch. This is what potterton told me to replace when the pressure was falling but it didn't help at all
BGas has offered to come and fix it as part of a maintenance contract. As it needs repaired they say it is £24 pm for the first year then it falls back to £16 pm.
Does these prices sound ok as the boiler is now 5 years old?.... I said yes to get the thing serviced and if there is a blockage hopefully get it fixed.
He's coming on Thursday. I will keep you guys updated and once again thank you all for your help! Us ladies need guys like you around
BGas has offered to come and fix it as part of a maintenance contract. As it needs repaired they say it is £24 pm for the first year then it falls back to £16 pm.
Does these prices sound ok as the boiler is now 5 years old?.... I said yes to get the thing serviced and if there is a blockage hopefully get it fixed.
He's coming on Thursday. I will keep you guys updated and once again thank you all for your help! Us ladies need guys like you around
- Joined
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Crazi i would have to say especially if you havent got a scale reducer fitted that it sounds like the heat exchanger is scaled up
this particular type of h/exch is very prone to this as it is a crossflow heat exchanger which is all part of the main h/exch
potterton would charge £275-00 inclusive to replace this
this particular type of h/exch is very prone to this as it is a crossflow heat exchanger which is all part of the main h/exch
potterton would charge £275-00 inclusive to replace this
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