set up of hand expansion valves

[modvalve]

Hi there I would like to know the best way to set up hand expansion valves. Some people say via the frost line and others say using 2 thermometers measuring liquid in vs out.

[RANGER1]

modvalve if you go into search forums "hand expansion valves" you will find what you want .ie
best td across coil
frost pattern on coil after defrost with fans off

[US Iceman]

This is always hard to explain.

1. You need to know what the coil TD should be and does it include the fan motor heat or is it based only on the coil capacity?
2. Sometimes people select the HEV (hand expansion valve) based on pipe size and not the intended valve capacity.
3. Selecting the HEV correctly someone should know how many turns open you would need to get the correct pressure drop across the HEV for the desired flow/capacity.
4. You also need to understand what the valves do. The essentially balance the flow rates/pressure through multiple coils. Each one may have a slightly different setting. Coils at a higher elevation will be more open than those coils at a lower elevation.
5. Coils closer to the pumps will be adjusted for higher pressure drop across the HEV.

Then after all of this, you can fine tune the valve setting by watching the frost pattern on the return bends with fans off. Once the last return bend starts to frost the valve should be reasonably adjusted.

You can confirm this by measuring the coil TD (air inlet minus air exit temperatures).

[modvalve]

OK thanks for that unfortunately the hand expansion valves are on the coolstore roof so it takes 10 minutes to reach the evaporators I think I have set them up as best I can 2 turns open

[Bhagwan Harani]

Differnce between water/Brine Temperatur & Suction Temperatur should be 7 Deg C