Reznor FX05 - Discharge;Duct Sensor

Form CP-MAPS-D12 with FX05, Page 20
FIGURE 9A -
Discharge Air Sensor,
P/N 206112, and
Holder, P/N 115850,
for Ductwork
Installation
Discharge/Duct Sensor
All systems have a discharge air sensor. The discharge sensor element on
cooling only or cooling with reheat systems (Models RCA/RDA) is attached to
the discharge opening of the system. On systems with a heat section (Models
RDCA/RDDA/RECA/REDA) or Models RCA and RDA with Option DU1, the
sensor is temporarily installed for heater startup but must be relocated to the
ductwork .
When installed in the ductwork the sensor must be housed in a mixing tube
which is attached to a 2x4 electrical box. The assembled parts (See FIGURE
9A) are shipped in the control compartment. Read the instructions below and
follow carefully to relocate the discharge air temperature sensor.
Discharge Air Temperature Sensor Location - Apply to all Models
RDCA/RDDA/RECA/REDA and Models RCA/RDA with Option DU1
Placement of the discharge air sensor in the ductwork is critical to the correct
operation of a MAPS system in both the cooling and heating modes.
Due to the split burner and dual heat exchanger features of the MAPS gas
heat section, duct conguraiton and sensor location is extremely important in
the heating mode when equipped with a gas heat section. The gas heat sec-
tion of the MAPS unit is designed to conserve fuel by only ring a portion of the
burner or one of the dual heat exchangers as required to supply the demand
for heat. Improperly locating the sensor can result in poor control of discharge
temperature.
Sensor Data
and Application
(cont’d)
FIGURE 9B - On
units with a gas heat
section, avoid an
immediate “T” in the
discharge duct
Hot
Air
Cool
Air
Gas Heat Section
If the unit is installed in a system with immediate “T”
configuration leaving the discharge, the 1/3 – 2/3 burner
design may allow stratification of the air. The result is hot
air only moving down one segment of the duct while cool
air moves down the other segment. Avoid this application.
If this application is not avoidable, provide air mixing
devices or the necessary duct length before the “T” for
mixing of the discharge air.