Evaporator Pressure Regulators

Caution with using evaporator pressure regulators.
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Firstly, I am a fan of them, they are problems solvers!. They make your day perfect and set the saturation temperatures final. The ability to lock humidity in a coolroom by locking the final evaporator temperature difference. Changes in condensing temperatures do not create problems with floating evaporator pressures.
But.... If you fit one, make sure that the system is well matched for capacity , meaning the outdoor and the indoor are ideally suited as a one to one system. If used in a multi-temp system with larger compressors operating more than one indoor, you must make sure that the system can unload.
If not, you will cook your compressor, run up the amps, decrease volumetric efficiency and increase the heat of compression.
The picture below shows the problem faced by excessive compressor displacement by being too large.
Caution always recommended.... good system design a must..