baxi megaflow 32 he overheating fault

cdlee · 13 Sep 2014

Hi, Just spoke to baxi after I have eliminated all of the possible simple problems causing the boiler to overheat but after all of this the boiler played with me by pretending it was OK then overheated and displayed E125 again!!!!!
The timer will turn the water heating and CH on at the correct times and the actuator vales are working perfectly and switch off when they are supposed to. The is absolutely no air in the system and doesn't appear to be any blockages. In fact the system is around 4 years old and the water is very clear as I do make sure the system is drained and inhibiter added etc.
Before I pay Baxi huge amounts of money for what may be simple I was wondering is anyone would be able to advise on what the problem could be.
When the water and heating turns off you can hear the valves close as they should but the boiler continues (doesn't shut down) and consequently overheats.
I would be vey grateful for the advice. I love reading the responses on this site so I though I would sign up. Odds are even for the first response to be you shouldn't have bought a baxi

bazdaman · 13 Sep 2014

I would be checking external controls first

Agile · 13 Sep 2014

Have you had the boiler serviced every year?

Tony

bazdaman · 13 Sep 2014

Agile said:
Have you had the boiler serviced every year?

Tony

Probably not customers seem to only get them "serviced" when there is a fault

dreadnoughtheating · 13 Sep 2014

Is there an 'auto by-pass' fitted to allow pump overrun to discharge residual heat?, are all rad valves the Thermostatic type, and closed down for the summer?

Just two possible avenues.... and not Gas safety critical.

DH

cdlee · 13 Sep 2014

Hi, Thanks for you comments, I am having all of the external controls checked with all of the correct equipment by an electrician friend and then it will be back to the boiler. I haven't had the actual boiler serviced but I have maintained everything else really well and will fitting a fernox TF1 filter soon. I am Trying to get to the bottom of the overheat issue on the boiler and working out if it will be more economical to get it fixed by a local tradesman (preferred) or sell my soul to the devil and pay for a maintenance plan (includes repair and service). I would love to work out the issue an repair at a sensible cost.
I am no sure about an auto overrun unless it it already in the boiler. I have thermostats on every rad apart from bathrooms. Boiler worked perfectly u I'll we tried the heating after a long break over summer. Thanks to everyone.

dreadnoughtheating · 13 Sep 2014

If your boiler is a Baxi MegaFlo it has the pump and circuit boards to control it all built into the casing... The external controls 'tell' the boiler to fire when a demand is made, in theory they also stop the the boiler from firing, leaving any residual heat to be dissipated by leaving the pump running for a period until the boiler cools. I say in theory, because the heads can malfunction and send erroneous messages to fire (or not fire)

If there is nowhere for the heat to be dissipated via an auto by-pass for example, which opens when the other valves are closed, forming an open circuit for the pump to push water through. (an 's' plan really rally should have one fitted), then overheating (E125) due to lack of circulation will be displayed

DH

cdlee · 13 Sep 2014

Hi,the system has worked perfectly for 4 years in it' s current layout, and after turning the heating on after a break the boiler doesn't carry on running for a very short period once the actuator closes it just carries on going, so the boiler isn't turning off at all until it over heats. It's as though the external controls aren't telling it to stop or the boiler controls aren't responding. I am definitely going to look at the bypass and if required update when I fit the filter. Would it be as straight forward as bypassing the actuator on the CH? Thanks again

cdlee · 14 Sep 2014

dreadnoughtheating said:
If your boiler is a Baxi MegaFlo it has the pump and circuit boards to control it all built into the casing... The external controls 'tell' the boiler to fire when a demand is made, in theory they also stop the the boiler from firing, leaving any residual heat to be dissipated by leaving the pump running for a period until the boiler cools. I say in theory, because the heads can malfunction and send erroneous messages to fire (or not fire)

If there is nowhere for the heat to be dissipated via an auto by-pass for example, which opens when the other valves are closed, forming an open circuit for the pump to push water through. (an 's' plan really rally should have one fitted), then overheating (E125) due to lack of circulation will be displayed

DH

cdlee · 14 Sep 2014

Hi, when you say heads do you mean the heads of the actuators as currently the main culprit may well be the CH head. Really appreciate you feedback (spot on) once sorted I will definitely looking at the bypass if it doesn't already exist. Thanks!

dreadnoughtheating · 14 Sep 2014

Yes, the actuator heads can malfunction. But the wetside can also seize in the open or shut position, there is usually a short lever on the head that can be moved by finger pressure, this might free it up if stuck with debris lodged inside.

Can you post up a picture of the two motorised valves?

DH

cdlee · 14 Sep 2014

Hi just spent the afternoon checking all of the external controls with my electrician friend. Everything seems to be in order apart from the CH actuator which managed to keep the boiler on even with the timer in off position, we removed it and even with with the front panel off the timer the boiler would still fire up and overheat. Disconnected the CH actuator and the whole system including the boiler are running like new without issue. Danfloss HP22's clearly developed a mind of their own which still performing the mechanical duties perfectly which was exactly what was throwing me off course as I was assuming that they were OK.
DH's feedback was superb as it kept directing me back to the actuator, so thank you ever so much for this. New head about to be ordered so fingers crossed all will be back to normal by the middle of the week and no need for the maintenance plan YEH!!
Love diynot and will definitely make this my first point of call.

Untitled

cdlee
14 Sep 2014
1

cdlee · 18 Sep 2014

Hi,

Part arrived yesterday (£33.84 delivered). 15 minutes to fit, 20 minutes testing and all is as good as new.

Thank you all for your input.

KR

P.s. Very happy and a bit hot!!

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baxi megaflow 32 he overheating fault

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