Robertshaw SLIMZONE ENVIRONMENTAL MODULE - Manual (Page 5)

not be required. This is based on duct sizing where either zone is able to handle approximate-
ly 75% of the total system CFM (cubic feet/minute). This will result in only slightly higher
air velocity at the discharge grille if only one zone is calling and yet allow for proper CFM
across the cooling coil.
Bypass activities are fully controlled by the SZEM module, which monitors the system static
pressure and modulates a motorized bypass damper accordingly. The static pressure value is
communicated to the SZP control module.
HIGH AND LOW TEMPERATURE LIMITS
When bypassing conditioned air it is important to consider high and low limit control to pre-
vent coil freeze up or overheating. The SZEM module also monitors the conditioned air tem-
perature and signals the SZP control module when the high and low limits are exceeded.
System air temperature value is communicated to the SZP control module.
OUTDOOR TEMPERATURE MEASUREMENTS
In heat pump applications, the outdoor temperature may be used to determine when to lock
out either the compressor(s) or auxiliary heat (high and low balance points). Outdoor air tem-
perature is communicated to the SZP control module; outdoor temperature value may be dis-
played at both the SZP module and zone thermostats.
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