Quote Originally Posted by Gary View Post
Given there is a HX after the bulb, if the bulb charge has not migrated, then the TXV should modulate closed and not allow frost back to the compressor.

On the other hand, if the suction is frosted back to the compressor, then the bulb (on the other side of that HX) should be cold enough to take back its charge... in which case it should modulate and prevent the frost at the compressor.

So... why does adding a small amount of charge cause frost back to the compressor?
I have had a look on the danfoss site does not give superheat control limits (adjustment) but does give varying detail to open 11C SH to open to design. This then shows that you would expect frost. Also valves do not close 100%, so present valve could be giving 1KW of load at maximum shut down, which likely to be greater than the plate load, thus liquid floodback may occur.
The present orifice matches chefs equivelent compressor duty (which practically is not as high as he predicted) I am not saying it has not migrated, but neither would i presume it was.