Bosch singular 5200 combiboiler shuts off

jdbubb

I have a Bosch Singulair 5200 Combi boiler that was installed two years ago. It has worked well, but this season it will occasionally cycle off. In other words, after it has run its cycle and space heating is no longer calling for heat It will cycle down and then completely shut off. It does not do this every time. There seems to be no consistency and when it will shut off and when it will just remain on, waiting for the next call for space heating.
I don’t know at what point it shuts off, but I will come back to the workshop (where the unit is located) and it is cooler than it should be, the thermostat is calling for heat, and the unit is off (as in powered down).
could it potentially be a faulty thermostat?

neilc

when you say "completely shut off", do you mean no lights at all? no indicators on the boiler? no power to boiler? (I guess not as you say you have a thermostat calling) or do you have a power to boiler issue?

or just that it doesn't restart for more heat?

either way, what are you doing to restart your heat? power cycling(resetting) the boiler?

if boiler is powered, jump the thermostat terminals at boiler, does boiler go for fire?

AND, or,

are there error codes(LED flashes?) displayed?

do you have your manual?

do you have a meter and knowledge to use it?