Gabarron CMX15 Safety Cut-out tripping

[Alan-N]

Hi Gents, full disclosure. Electrician not a plumber. Got called to look at a Gabarron CMX15 that was dead, discovered the Safety Limiter device on the CH side had tripped, reset it and bled the radiators are recharged to 1.5bar per the manual. long story short it has tripped a couple of times since. Done it today while I was there after only being powered up for 5 minutes, the water was stone cold and the Sr value was 18 (from the diagnostic routine) , it also this time refused to reset even with the mains power off. In my mind the device itself is faulty. I did call Elnur UK but the bloke didn't seem to have a clue and wanted me to send him all the details in an email, never got any reply. Am I missing any other reasons for that switch to keep tripping

 

[Deleted member 120897]

I would look at the pump, disconnect this and see if it resets.

 

[Alan-N]

I would look at the pump, disconnect this and see if it resets.

The pump appears to be working, it ran for 5 hours one of the times before tripping, last time barely 5 minutes. Its the last time that to me makes it look like a dodgy thermal cut-out switch as I can't see how it could possibly have reached its thermal limit. Trouble is finding one

 

[Alan-N]

Update : Elnur (UK agents for Gabarron) got back to me and asked me to turn off HW & CH and check with a clamp meter what the boiler was drawing. I was dubious but gave it a go. Boiler with nothing on was drawing just under 3KW, and I could hear water starting to boil. This they tell me is a faulty main PCB causing one of the elements to never turn off, hence it keeps working until the safety cut-out pops.