RH-D AND RH-W ELECTRIC DUCT HEATERS
RENEWAIRE.COM
INSTALLATION, OPERATION AND MAINTENANCE MANUAL
1.800.627.4499
22
MAINTENANCE
7.3.3 Testing Heating Elements
7.3.4 Testing the Transformer
7.4.1 Testing the CTH291 Thermostat
7.4.2 Testing the S2 Airflow Sensor
7.4.3 Testing the PSSR Control Module
Make sure the automatic and manual thermal reset are in the closed position. Measure the resistance
between LOAD 1 on the D21-T board and L2. If the reading is OPEN LINE, replace the heater. If the
board is a D22-T, also measure the resistance between LOAD 2 on the D22-T board and L2. If the
reading is OPEN LINE, replace the heater element.
Power the primary side of the transformer. Measure Voltage across the secondary terminals. Voltage
should be 24 VAC.
7.4 RH-W TROUBLE SHOOTING
Review wiring of thermostat (and sensor, if duct control application). (Refer to instructions supplied
with the thermostat).
Review Dip Switches settings. (Refer to instructions supplied with the thermostat).
Note for Dip switch 2:
Reverse acting: 0-VDC = Full OFF /10VDC = Full ON (RenewAire DEFAULT).
Direct acting: 0-VDC = Full ON/ 10VDC = Full OFF
Troubleshooting notes:
1) If the display is showing two straight lines, the external sensor is defective or not connected to
terminal 7 and 8 (if configured for external sensor – Dip switch 3 = ON). Circuit is open: resistance is
infinite or high.
2) If the temperature sensor is out of measurable range, the display will indicate HI (when the measured
temperature is higher than the top bracket of the temperature range) or Lo (when the measured
temperature is lower than the lower bracket of the temperature
range).
3) Power has to be switch off and on (RESET) after dip switch is changed.
Example: If dip switch 3 is set to external sensor (ON) and no sensor is connected, the screen will show
2 lines; if dip switch 3 is then set to internal sensor (OFF), 2 lines remain as long power has not been
reset.
4) When the thermostat is in heating mode, a sun will appear on the display. It will flash when there is
a call for heat. When the thermostat is in cooling mode, a snow flake will appear on the display. (To set
cooling mode, install a jumper between terminals 2 and 3).
Remove S2 airflow sensor from PSSR board and measure the ohms across the Thermistor:
The reading should be 10KΩ at 77 F. If the temperature is higher, the resistance will go down and if the
temperature is lower, the resistance will go up. If the sensor reads OPEN LINE, replace sensor.
Input: 0-10VDC
Shorted or broken Air-Flow sensor detection:
If the air-flow sensing Thermistor connection (A-A) of the D21-PSSR controller is either shorted or
open, the controller will continue to work normally for about 60 seconds. While in this 60 second
period, the yellow (or red) light begins to quickly blink indicating this warning mode. If the normal air-
flow condition is reinstated within that 60 seconds, the controller goes back to normal operation and
the yellow (or red) light turns OFF. If the normal air-flow condition does NOT come back within the 60
second time frame, the yellow (or red) Warning LED light begins to flash with a pattern of 1-second ON
and 2-seconds OFF, and the controller switches off the SSR output (i.e. lockdown).
To cancel: fix the short or open air-flow sensor connection, and then turn the controller’s power OFF
and then ON.
