Hello

I am about to fit a domestic walk in dairy fridge set point 5c load about 1kw. Danfoss Optyma outside, Searle TEC Evaporator inside.

Pipe run is about 25M and the outdoor is above the indoor by about 1M, similar to a cellar.

Liquid 1/4 copper
Suction 3/8 copper

I have been advised by my supplier to reduce the suction for oil return to 1/4 where the pipework rises, this would be a couple of sections about 500mm.

Can anyone explain the thinking behind this theory, I've never come across this before and I am unsure about reducing a 3/8 suction to 1/4.

Thanks