Gulfstream overheat sensor pops out

[Goldspoon]

I'm not a heating engineer or Gas Safe. I drained a Gledhill Gulfstream 2000 thermal store (has its own boiler) then re-filled (fitted a rad).

Overheat sensor, top left, pops out after hot water and heating on (after about 30 mins).

It is not the AAV as this works (hisses when re-filling).

Any clues on what to do?

I am happy to get a heating engineer out if required - just looking for anything simple I might have missed.

 

[nickso]

only drained two of these awful contraptions down and not had a problem when refilling. the thermostats on these are cheap garbage and regularly fail. check what temperature the storage tank gets to and make sure the stat closes.

 

[Goldspoon]

thanks - will do so