Expansion Valve Placement
It is critical to replace an air conditioning or refrigeration Thermostatic Expansion Valve (Abbreviated TEV or TXV) with a new one having the correct refrigerant flow capacity, selective charge and equalizer. But even the right TEV or TXV installed incorrectly can give unsatisfactory results.
TEV and TXV's may be mounted in any position so place them in such a way that the superheat adjustment can be reached easily. TEV and TXV's should be installed as close to the evaporator as possible. If a refrigerant distributor is used with the expansion valve, the pipe between the expansion valve outlet and distributor should be as short and as straight as possible. The best situation is if the distributor can be mounted directly to the expansion valves outlet port.
If the distributor cannot be mounted directly to the valve outlet, the distance between the expansion valve outlet and distributor should not exceed 24 inches. If a change of direction is necessary, bend the tubing. Never use elbow fittings in between the expansion valve outlet and distributor!
To avoid the effects of gravity, the best design is to place the expansion valve outlet so it feeds refrigerant vertically up or down into the distributor. (Remember: you want to make "Freon fountains instead of Freon faucets" ).