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Discuss Reliability of fault codes potterton in the Central Heating Forum area at PlumbersForums.net

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2
HELP!,,,, E125 error code
Been trying to get to the bottom of problem with potterton titanium 40.
keep getting e125 which is circulation fault ( primary circuit). Fault is intermittent.
Thought about system flush but seem am reluctant as
all rads are red hot. Return pipe also hot.
Fault generally becomes noticeable when hot water is drawn off and then just runs cold.
May also happen when just on heating mode but not sure if this is triggered by water being drawn off while the heating is on, that locks up
again giving E125. can usually get it to reset ok but usually goes again same day.
sometimes can go a week or more without problem


have done the following with no success:

Back In December drained system down. (water was a bit black but no sludge) , ran system cleaner for few hours.
then drained off. Flushed. fit inhibitor and refilled. Next day got e125 but was then ok for about 8 weeks. Rads still all getting hot enough

Renewed C H temp sensor and safety thermostat.
Pump appeared to be a bit ‘sticky’ so fitted new one
Removed and cleaned 3 way valve and fitted new diverted valve ( didn’t really need cleaning)
Removed and checked flow pipe from burner to 3 way diverted valve. Was clean.
Removed and flushed plate heat exchange ( was clean anyway! Great flow on DHW side and primary circuit when using hose pipe on it)
As fault appears intermittent also ran it with a new pcb. Still got same e125 code so refitted original.

Back to square one!,



any pointers will be appreciated.
 
Messages
1,760
circ problem may be detected by primary flow/return temp sensors so if still flagging alarm after renewing circ pump perhaps one of these sensors, if return sensor fitted.
 
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Messages
24
Thanks for the replies @John.g and @Undertrained

My particularly problem is slightly different than the OP. I have a Baxi Platinum combi boiler. Working fine until I had wet UFH fitted.
If I just turn on UFH then it runs fine. If I turn on the radiators as well then I get E125 circ fault.
If I turn off the UFH then radiators work fine. So it's just a problem with both of them on.

Sounded very similar to the original post that I found during a bit of Googling so wondered if his answer would help lead me to sorting my problem. :)
 

Undertrained

Plumber
Gas Engineer
Messages
365
Thanks for the replies @John.g and @Undertrained

My particularly problem is slightly different than the OP. I have a Baxi Platinum combi boiler. Working fine until I had wet UFH fitted.
If I just turn on UFH then it runs fine. If I turn on the radiators as well then I get E125 circ fault.
If I turn off the UFH then radiators work fine. So it's just a problem with both of them on.

Sounded very similar to the original post that I found during a bit of Googling so wondered if his answer would help lead me to sorting my problem. :)
I suppose this is why threads shouldn’t be hijacked 😉 It’ll still be a circulation issue, perhaps the pump isn’t capable of the 2 circuits together?
 
Messages
24
I suppose this is why threads shouldn’t be hijacked 😉 It’ll still be a circulation issue, perhaps the pump isn’t capable of the 2 circuits together?
Yep, was conscious I was hijacking the thread with my last post :(

Was originally just wanting to learn from whatever solution the OP ended up with. But, didn't account for other experts pitching in to help :)

As for the pump, there is a separate pump on the UFH manifold and then the boiler pump itself so (although a good suggestion) I'm not sure that would be it? (although worth noting that you could probably write what I know about plumbing on the back of a stamp!) :)
 
Messages
24
Some boilers detect the slight rise in pressure when the circ pump starts so possibly a blocked/partially blocked pressure sensor or tubing..
Thanks John G. The boiler was going quite high with pressure previously but the plumber fitted another expansion vessel above the manifold. I'll put on the heating though and see what pressure the boiler jumps to when it tries to run both the UFH and the heating. Thanks for the potential diagnosis :)
 
Messages
1,760
Is the boiler pump inside the boiler (system boiler). Did the problem start after the installation of the extra expansion vessel? is it positioned on the flow manifold or the return manifold?.
 
Messages
24
Is the boiler pump inside the boiler (system boiler). Did the problem start after the installation of the extra expansion vessel? is it positioned on the flow manifold or the return manifold?.

The boiler is a Baxi Platinum boiler and has a pump inside it. There's another pump on the manifold of the UFH. The problem started after the UFH was fitted but before the expansion vessel was fitted.

Sequence of events was...
Boiler running fine with just rads.
UFH installed and turned on
Boiler dropped out with E125 (which the manual lists as "Circulation Fault (Primary Circuit)"
I powered off the UFH Wiring Centre (it's fed from a switched fused spur) - rads all ran fine
Plumber came back out and said a valve was shut on the manifold which he opened - he was concerned about the pressure the boiler was reaching though (around 2.5 bar) so also fitted an expansion vessel above the UFH manifold
UFH ran fine for several days (until last night when I put the heating back on as it was a bit chilly).
With heating on got the E125 fault again.

As for whether the expansion vessel is fitted on the flow / return I'm not 100% sure. I've just got to nip out for an hour but I'll take some photos when I get back and post them up here to show you the set up. Thanks for all your help. Very much appreciated :)
 
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Here are some photos of the installation as promised.***.
 

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