Why Low Ambient when you have an Economizer
Why Low Ambient when you have an Economizer
(OP)
Just a general question here. It seems like every specification for rooftop units calls out for both low ambient controls and an economizer. If you are bringing in cold outside air through your economizer, your compressor is off. So why do you need low ambient controls?





RE: Why Low Ambient when you have an Economizer
Say a Tech made a general check on the health of an existing airconditioning system and discovered that the indoor section had frozen up, and the cause of this was running the airconditioning when the outdoor temperature is below 65 degrees. The solution is to add a 'low ambient kit".
The low ambient kit works by slowing the fan to maintain head pressure so that the TEV (thermostatic expansion valve). will meter refrigerant properly. The fan speed is controlled by a temperature sensor connected to the copper tubing on the condenser. In other words too low a head pressure = a starving coil = SST below 32 degrees = frozen coil and possibly compressor damage due to slugging, lack of oil return ETC,ETC.
RE: Why Low Ambient when you have an Economizer
I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI