Myson Midas SI

[GeordieA]

Hi

new on here but can anybody help with an intermitten fault with my Myson.
The hot water & central heating can work ok for days & then all of a sudden just cut out, I then have to switch everything off including the mains, leave it for a few minutes and then switch the mains on then the hot water & everything works fine until the next time.
I have had the BG man out a few times & they have changed the PCB & 3sensors + the air flow sensor but still the fault persists.
please any ideas anybody.

ps I know nothing about boilers

 

[compheat]

The Midas SI can be a swine to work on! It's a well made boiler a bit over complicated. It as a over heat stat that needs resetting manually so it cant be that. The PCB is fitted with LCD (lights ) which can help you to fault find. Because the fault is on both DHW and Heating its got to be common to both ie: fan, fan sensor, gas valve, PCB,Why havent BG come back to fix???

 

[gazthepottertonengineer]

they probably told him he needs new boiler

ive had similar problem with this boiler before and its always been the hot water sensor that goes into the bottom of the little store

 

[ollski]

they probably told him he needs new boiler

Probably, tends to happen quite often when you need to work on appliances over 5 years old

 

[Pogle]

Hi

new on here but can anybody help with an intermitten fault with my Myson.
The hot water & central heating can work ok for days & then all of a sudden just cut out, I then have to switch everything off including the mains, leave it for a few minutes and then switch the mains on then the hot water & everything works fine until the next time.
I have had the BG man out a few times & they have changed the PCB & 3sensors + the air flow sensor but still the fault persists.
please any ideas anybody.

ps I know nothing about boilers

I have been experiencing similar faults with my Myson SI for months. It used to continually overheat and cut-out. I would have to remove the burner front cover and fix the reset button that shuts done all functions located upper righthand side,or reset the cut-out underneath and to the right of the water storage vessel. I have fitted a new pressure relief valve and central heating flow sensor. After refilling and purging of air this improved the performance for a couple of weeks. But now it fails to light on it's own. The fan is going around and you can hear the board clicking as though trying to ignite but as the fan ramps up speed, the ignition just seems to give up. The only thing I can do now is shut down the mains, turn off the gas valve so as to extinguish the pilot. When gas and electricity are switched back on the boiler will light and run until hot and then cut out again. I have just noticed a slight seep from the gland nut of the new pressure relief valve which I will have to seal, although the dial pressure is still 1.5 bar. Is it anything to do with either of the Red vessels? how do I pressurise them what is the procedure. Any ideas anyone? Please.....make my Christmas and save our marriage. Layman's terms please.

 

[ollski]

sounds like the air flow sensor, those and moisture dripping onto the sensors are the main faults I have come across on these.

 

[Pogle]

sounds like the air flow sensor, those and moisture dripping onto the sensors are the main faults I have come across on these.

Cheers I'll check these out. Where are they located and what do they look like? Any other suggestions? What about pressurisation?

 

[HarrogateGas]

Id check its had the right PCB fitted. There were two variants for this boiler and if the incorrect one is fitted you can get all sorts of funny faults.