Myson Apollo 80c cutting out

[wilroda]

I have the above boiler with 2 sunvic 2 port valves - SM5203.

CH run on its own operates fine.
HW run on its own works fine for 15 mins ish then boiler starts cutting out and restarting every 15 - 20 seconds - ish.

Have checked the valves and tank stat. These are not turning the boiler off.This is correct.

Can anyone tell me what could be turning the boiler off?

Thanks in advance

 

[wilroda]

Just to add to this query.

The hot water appears to be hotter than usual.

Hope this is of help in solving my problem.

 

[wilroda]

I am now thinking along the lines of replacing this boiler as i have been told that it is old and possibly not worth repairing.
What are the top combi boilers around? bearng in mind we have 10 rads and a power shower.

Thanks in advance

 

[bster]

are you 100% its not the tank stat (cylinder stat)?

 

[wilroda]

Yes i am 100% sure its not the tank stat.

There is feed through the tank stat,through the actuator micro switch to the electronic controller.The electronic controller tells the boiler to go which it does.....it is the boiler itself that is shutting down.

The only thing that I can see that turns the boiler off is the high or low boiler temp switch.The boiler is currently set to Low but will run in High mode.

Is there anything else that could shut the boiler down?

 

[namsag]

If heating is working perfectly this indiates nothing is up with the boiler. It is probably the sunvic valve head breaking down in use and coming off an on the microswitch inside it , also some programmers also breakdown during demand but this is very rare. If programmer has indicator lights these usually flicker on an off when they have a fault.

 

[wilroda]

Thanks very much for that. This really is a puzzle!

Other half is a sparky and has checked the programmer (and valves etc) which is working fine. He surmises that the problem could be a thermostat within the boiler but i can see your point about the boiler being fine if heating is working ok.....

 

[namsag]

If he is a spark tell him to disconnect wiring and swap the heads over if the hot water now works ok and heating doesn`t fault is with the head .If the fault still persists it is either cylinder stat or programmer or even something simple like a loose connection.

 

[wilroda]

Thanks for that namsag!!

I shall keep you posted on our progress!!

 

[namsag]

I know this is prob stating the obvious to a spark but make a note of what colour wires come from which terminals etc so nothing gets put in a wrong terminal during changing.

 

[wilroda]

Thanks for the tips!

OH has a busy day planned for tomorrow then!

His question is this..
What are the temperature trip values of the upper and lower thermal trips in the boiler?....A myson apollo 80c

Thanks in advance for all your help.