A
W-TRAC
IOM‐49
7 of 12
Mar 99 R4
INDICATION
AND
DIAGNOSTIC
LIGHTS
On the face of the W‐TRAC are 5 red LED indication lights.
Light
Description
Low Exhaust
Temp
Indicates the exhaust temperature is below the calculated minimum allowable
temperature, which is based on the amount of moisture in the return air (measured
or estimated) and the ambient temperature.
Bad Sensor
Shorted or open sensor indication.
Vent Mode
Wheel will be stopped. No call for heating or cooling.
Discharge Too Hot
Wheel is slowing down due to excessive recovery of heat.
Frost Mode
Heat wheel rotation speed is reducing to prevent frost accumulation.
ADJUSTMENT
POTS
There are a number of setting and calibration potentiometers (POT’s) located on the face of the W‐TRAC.
Modifications to these should only be done by experienced and qualified personnel.
POT
Description
DIS CAL
Discharge temperature sensor calibration.
EX CAL
Exhaust temperature sensor calibration.
AMB CAL
Ambient / outdoor temperature sensor calibration.
BDRH
Predicted design return air RH% scale (1‐4).
TEMPERATURE
CONTROL
The W‐TRAC has 4 modes of operation; Heat, Defrost, Vent and Cool, that controls the wheel rotational
speed to achieve the desired temperature setpoint of supply air leaving the wheel.
When the outside air is colder than the exhaust air, the heat wheel will rotate to capture heat from the
exhaust air side and transfer it to the supply air stream. Increasing the rotation speed will increase the
amount of heat transferred.
If too much heat is being removed from the exhaust air stream it is possible for frost to accumulate on the
face of the heat wheel. The W‐TRAC will automatically reduce the rotation speed to prevent frosting.
If no heating is required, the W‐TRAC will stop the wheel rotation and enter ‘vent mode’.
