Robertshaw SlimZone PREMIER ZONE CONTROL SYSTEM - Manual (Page 14)

4.6 SLIMZONE ENVIRONMENTAL MODULE (SZEM)
INTRODUCTION
The SlimZone Environmental module (SZEM) is an
optional component in the SlimZone Premier system. The
module provides the following services:
• Bypass damper control and static pressure sensing
• High/Low temperature limit signaling
• Outdoor temperature measurement
DATA EXCHANGE
All information collected by the SZEM module is communicated to the SlimZone Premier
control module (SZP) via a RS485 communication port at 1200 baud. All information received
by the SZP control module may be viewed by the user (Figure 5.2).
BYPASS SYSTEM
In order to maintain proper air flow and static pressure throughout the HVAC system, a bypass
system should be used. In some 2-zone applications, a bypass damper may not be required.
This is based on duct sizing where either zone is able to handle approximately 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.
A single zone fan call may cause some air noise in large systems. If any single zone is unable
to handle the remaining 25%, the minimum air adjustment in the closed zones must be set to
accommodate the excess air. Single zone calls for equipment (fan, heating or cooling), may
cause air noise and/or temperature overshoot in large systems. This is the result of excess air
being discharged through the zone diffuser. When this occurs it is recommended that the user
select a similar call from an additional zone in order to alleviate the amount of air going to the
single zone call.
Note: This situation can occur when the SZP Control module is in the auto fan mode or when
a single heating or cooling call occurs from Must-Service zones.
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 prevent
coil freeze up or overheating. The SZEM module monitors the conditioned air temperature 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
temperature is communicated to the SZP control module. Outdoor temperature value may be
displayed at both the SZP control module and zone thermostats. Refer to the information
provided with the SZEM module for detailed installation instructions.
SlimZone Premier 11