Reliability of fault codes potterton

[johnnyt74]

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

 

[johnnyt74]

Here are some photos of the installation as promised.....

 

[John.g]

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.

Found this somewhere but can't download your manual.......

E125 is displayed in either of two situations:-
i) If within 15 seconds of the burner lighting the boiler
temperature has not changed by 1°.
ii) If within 10 minutes of the burner lighting the boiler
temperature twice exceeds the selected temperature by 30°.
In these instances poor primary circulation is indicated.

So seems to be solely based on temperature, presume it means in (i) that if the temp doesn't increase by 1C in 15 secs that it flags the alarm, it would be quite possible to get a slug of cold water for > 15 secs after burner start up with no increase in temperature.
ii) might seem a bit unlikely as the burner should shut down when the temperature = target temperature+5C, except that its stll monitoring it during pump overrun.

At least its something to concentrate on as it seems to be purely boiler flow temperature monitored?.

Maybe try and monitor the time after ignition and see how long it takes to trip.

 

[johnnyt74]

At least its something to concentrate on as it seems to be purely boiler flow temperature monitored?.

Maybe try and monitor the time after ignition and see how long it takes to trip.

Yep, I'm planning on giving that a go later. I've got a couple of guys working here at the moment through in the extension (where the UFH is) so don't want to cook them! It's quite a warm day today and they're plasterboarding which is hard going so will wait until they finish later and then try and put both the UFH and rads on and monitor the boiler pressure / temperature and the time to trip.

I've attached the manual for the boiler.

Thanks for all your help

 

[ShaunCorbs]

there’s no external auto bypass also the install looks like the builder has done it

So when the ufh shuts and the rads are just calling eg just opening the pump is dead heading against two port valves so no circulation for a few seconds hence e125

 

[John.g]

There is a ABV set to ~ 1.2M in photo 7 post #12, what does this do?.

 

[ShaunCorbs]

There is a ABV set to ~ 1.2M in photo 7 post #12, what does this do?.

That’s the minimum flow rate to stop the boiler cycling too much and throwing errors up as the ufh doesn’t need much flow hence why it’s set to 1 eg open all the time

Also looks after the upstairs port valve I’m guessing the 2 hep feeds going through the wall central of the boiler is the ufh feed

 

[johnnyt74]

there’s no external auto bypass also the install looks like the builder has done it

So when the ufh shuts and the rads are just calling eg just opening the pump is dead heading against two port valves so no circulation for a few seconds hence e125

Which part looks like the builder has done it? In the boiler cupboard? Or the UFH?
If it's the UFH it's just been lashed in at the moment for testing. It'll all need cleaning up and re-wiring etc to make it neat. The plumber only has one guy who can do the electrics so he'll come back and sort it at some point.

That’s the minimum flow rate to stop the boiler cycling too much and throwing errors up as the ufh doesn’t need much flow hence why it’s set to 1 eg open all the time

Also looks after the upstairs port valve I’m guessing the 2 hep feeds going through the wall central of the boiler is the ufh feed

You're right, the two white plastic pipes going through the wall are the ones he ran in for the UFH.

So, I need to ask the plumber to install an external auto bypass? I thought that's what that black thing at the top right of the UFH manifold did? The plumber said that "automatically bleeds the system"? Is that not correct? (the bit I've circled in the attached photo)

Thanks for all the help. I really appreciate you taking the time to have a look at this.

 

[ShaunCorbs]

All the pipework under the boiler

Do you know what’s the tee above the port valve in the cupboard eg the grey hep pipe where this goes ?

 

[johnnyt74]

All the pipework under the boiler

Do you know what’s the tee above the port valve in the cupboard eg the grey hep pipe where this goes ?

Yep, I must admit, I did think the boiler cupboard pipework looked like it was done by someone missing their mecanno set...

The grey pipe feeds a radiator that was an extra when the previous guy converted the garage to a room. The boiler is in the "what was" garage. And the grey pipes feed this radiator.

Thanks