Discuss Am thinking...plate heat exchanger gone blocked? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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mutley racers

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Hi fellers, I have just had a call from a client who has a potterton performa 24. She says her hot water only gets warm and the boiler stops and starts when in hot water mode. Its ok in the central heating mode.

So, I am thinking a blocked up heat exchanger. Now, is it worth me buying the heat exchanger before looking at the boiler and replacing? Or, should i check it out and test the stats?

Thanks guys
 
Check it out first, could be something silly, flow switch / transducer failing maybe?
 
Check the ntc I've found these are good for going, also definatly worth taking the plated off and checking they are easy enough to get out.
 
I think i shall just go without ordering the heat exchanger and take the one out and give it a wack to see if any scale falls out
 
I think i shall just go without ordering the heat exchanger and take the one out and give it a wack to see if any scale falls out
could be a failing dhw dipragm,diverter valve,blocked phex so no i would not just order one, unlikely to be a thermistor most 24 kw performas dont have one on dhw only the eco,s
 
I did see a post on here a while back and the guy had the same problem. Someone told him to take the heat phex out and whack it a few times. He did and scale fell out and hey presto. All was fine
 
All the guys who helped this guy have all but disappeared. Am sure there are a few I have wondered where they went. Where is unguided by the way?
 
dumping into the central heating side Gasman? i am definitely not going to buy it. Does anyone buy their stuff from Euro Boiler Parts? If so, are they any good?
 
dumping into the central heating side Gasman? i am definitely not going to buy it. Does anyone buy their stuff from Euro Boiler Parts? If so, are they any good?
flowpipe getting hot or rads warming up when running a hot tap thats dumping down yes euro boiler parts formally abkot are cheap but totally crap with in warranty claims very unprofessional IMHO
 
thanks gasman. I really need to find a decent spares supplier. Not many have the parts you need on the day you need them hey
 
flowpipe getting hot or rads warming up when running a hot tap thats dumping down yes euro boiler parts formally abkot are cheap but totally crap with in warranty claims very unprofessional IMHO

Do all boilers dump down or only certain ones?
 
Do all boilers dump down or only certain ones?
Depends on the condition of the diverter valve, new ones will resist heat tracing through to the heating flow, where as an old diverter valve with worn springs and seals will allow heat to pass by if the PHEX is blocked.

The way I try and determine whether the PHEX is blocked, is where possible, feel the flow and return from the primary heat exchanger, if the flow is untouchable and the return is noticeably cooler, the PHEX is likely at fault.

I have on several occasions cleaned partially blocked PHEXs by removing them and blasting the primary ports back and forth with an outside tap. Quite satisfying when you see little black lumps flying out.
 
The PHEX are a good idea but a weak blockage point especially in older systems. Perhaps somebody may come up with a better design.
 
The PHEX are a good idea but a weak blockage point especially in older systems. Perhaps somebody may come up with a better design.

Intergas have. Check out their boilers if u havnt already.

Sent from my GT-I9100 using Tapatalk 2
 
If the phex is blocked, as it certainly sounds like it. Don't just clear it or change it, as it sure is going to block again unless the systems totally cleaned. Explain this & if they don't want the system flushing, makesure you note this on the report/invoice that you are advising a flush & if not done won't be held responsible if & when it blocks again!
 
Well I just cannot seem to fix this problem. I took the phex out and looked through it and no noticeable scale. Then i hit it a few times with a spanner and nothing came out. Then i blew through it and my breath easily went through. So then got a cold tap from mains and ran that through. not a problem and no noticeable scale. All heat sensors ok.

Put it back together and it doesn't cut out any more, just doesn't get hot.

its a frustrating job this one
 
So when running the hot tap does the flow pipe get hot underneath the boiler?
Did you run water through both sides of phex?
Have you checked burner pressure?
Is it all the hot taps that are the problem or just one?
 
No the pipes don't get hot under the boiler. So it is not dumping. indeed i did run it through both sides of the PHEX. It is at all taps and the burner pressure while on the hot tap just kept bobbing up and down
 
but this problem just starting happening out of the blue, surely the gas rate wont change on its own? Or would it work for a bit if set incorrectly and then just develop the fault?
 
Ok, I'd say you need to check gas valve setting its in the mi's under the fault finding. Also you checked temp sensor these are good for causing problems on the performa. Checked working pressure? Sometimes get it where the ecv has been knocked almost closed.
Does the burner stay alight? Sooo many questions but it should help someone to help you diagnose.
 
I tried to check the burner pressure but as it was just bobbing up and down when in heating and hot water mode. Which is what it says to do the the installation manual. yes checked sensors and all are ok.Inlet is also fine. Even put my FGA on it to make sure it was burning ok and it was .0004 so am happy. I hate working on something for a few hrs and not fixing it. It means I don't get paid!!!
 
I'd personally change the temp sensor under the o/heat stat first it's prob the cheapest place to start. Does it get hot if the tap is running slow? Have you tried ringing tech help when on site?
 
it does get hotter when the tap is on slow but then there is no flow in the bathroom for a bath and the water is not hot then. I have continuity on overheat stat and at just above room temperature 9980ohms
 
No, have not tried calling technical yet. It says that you need to adjust the burner pressure in hot water and heating, but when on hot water is was bobbing up and down, so i just wacked the heating on full blast and adjusted the burner pressure to max there. Is that ok to do? As on the hot water it was just bobbing up and down from 2-4
 
I'd personally change the temp sensor under the o/heat stat first it's prob the cheapest place to start. Does it get hot if the tap is running slow? Have you tried ringing tech help when on site?

I agree with the sensor idea.
Tech will probably say change the PCB.
It might be an idea to visually check the board for dry joints or discoloured components tho.
 
Even though i checked both sensors and they were ok? i did not look at the PCB at all.
 
my temp sensor is above the overheat stat. Are there only 2 on this boiler then? I can only see them on the primary side to the left of the diverter valve
 
Which performa is it? The one I was thinking only has one stat just next to the o/heat stat.
 
Do you think it was ok for me to set the burner pressure on heating only? When it says to do it on hot water and heating? As i couldnt on water as it kept bobbing up and down?
 
even a blocked hex will flown water from a tap through it and blow easily you have to flush and bang iit into a bowl or bucket and see the little black bits comming out
 
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