DIGI3U DESIGN INFORMATION
2
2-3 Zone Application with Bypass Damper and LAT Sensor
– Use
this method if your application is for 2 or 3 zones using a bypass damper
and LAT sensor. Zonex Systems recommends that all systems use a
bypass damper and LAT to maximize system efficiency and comfort.
Ductwork design should follow typical duct design procedures: use
ductulator to verify airflow requirements, and follow bypass-sizing
calculations found in bypass guidelines of this manual.
2-Zone Gas/Electric Applications
without
a Bypass Damper or
LAT Sensor –
When designing a system without a bypass damper or
LAT, it is necessary to oversize the ductwork and supply registers in
order to reduce noise caused by excessive static in HVAC system. Duct
runs and dampers must be oversized by 70%, and supply grills must
be increased in size to move twice the volume of air at 700 FPM; e.g.,
if zone calls for 250 CFM and a 12x8 register were sized for non-zoned
application, double the volume of air to 500 CFM, and size register for
700 FPM, or a 14x8-supply register. If the Zonex Systems LAT capacity
control is not applied, a field supplied freeze protection and high limit
device must be installed to protect equipment. This should only be
applied to designs in which both zones are approximately the same size.
NOTE:
All Heat Pump installations require the LAT sensor.
1. Remove factory installed 1K ohm resistor on S S.
2.
Gas/Electric applications
– install sensor as far as possible from
the FAU heat exchanger but still before the bypass tap.
3.
Heat Pump application
– install the sensor after the indoor coil
but before the electric strip heat assembly.
4. Secure the sensor-mounting base to the duct or AHU cabinet (HP)
with the self-tapping screws provided.
5. Run wire from the LAT sensor to S S terminals on DIGI3U controller.
Insert one wire under each S terminal, and tighten terminal screw.
6. LAT does not require calibration.
DESIGN INSTRUCTIONS
THERMOSTAT INFORMATION
LAT CAPACITY CONTROL INSTALLATION INSTRUCTIONS
For
Gas Electric
applications use standard single stage Gas Electric, auto changeover thermostats.
For
Heat Pump
applications use a standard Heat Pump thermostat (1 stage cool / 2 stage heat) for STAT 1 position only. Use standard single stage Gas
Electric, auto changeover thermostats on STAT 2 and STAT 3 positions.
S S
DIGI3U System Controller
