Why isn't my Reheat (Dehumidification) working?
Process (Steps 1-16):
1. Does Reheat work in Test Mode? If yes continue on to the next step, if no proceed to step 4.
2. Check the Reheat configuration (Jumper cut on J1-3 & 5, Jumper on the RTOM J9, solid green LED on LED 3 of the RTOM) and the J2-10 input for 24Vac.
3. After verifying that the Reheat works in test mode you can power the unit down, disconnect the BAS (if applicable), the Zone Sensor/Thermostat (if applicable), and the Space Humidity sensor, then install a jumper Between LTB2 on terminals 7 & 12 to give the unit a Humidistat command. Reheat should activate after the compressor minimum off-timers. Jump to End.
4. Is the OAT sensor reading between 40 and 100 degrees F? Check at J8 on RTRM. If no continue to the next step, if yes proceed to step 6.
5. The Reheat is disabled when the OAT is below 40 or greater than 100 degrees. Jump to end.
6. Is the unit in “OFF” mode (through BAS, Thermostat, Zone Sensor, Emergency Stop, or another shutdown mode)? If yes continue to the next step, if no proceed to step 8.
7. The unit needs to be in Cool, Heat, or Auto mode and cannot be actively heating or cooling. Jump to end.
8. Are there any safeties disallowing compressor operation (i.e. HPC, LPC, etc.)? If yes continue to the next step, if no proceed to step 10.
9. Both Compressors (if applicable) must be available for reheat control. If either compressor is disabled then reheat will be disabled. The compressor also needs to have met the minimum off-time requirements. Jump to end.
10. Is the zone temperature within ZSHP+0.5<Zone Temp<ZCSP-0.5? If yes continue to the next step, if no proceed to step 12.
11. Verify that the set points are not too close together. If using a mechanical or local zone temp sensor set the zone comfort set points accordingly to optimize reheat, if using BAS widening the offsets may be required. Jump to end.
12. Is the Reheat being disabled by a BAS (If applicable)? If yes continue to the next step, if no proceed to step 14.
13. If a BAS is installed check the Reheat disable points. If no tools are available to check points then the BAS module can be temporarily bypassed to revert to local control. Keep in mind that if there are no setpoints provided locally (for example a 2-wire sensor is installed) the default setpoints are 71 degrees for heating and 74 degrees for cooling so the ZT must be between them as stated previously. Jump to end.
14. Are there any known sensor failures or active alarms on the system? If yes continue to the next step, if no proceed to step 16.
15. If the unit has an OA temp sensor failure, a Zone Temp sensor failure, a Space Humidity Sensor failure, or any other alarm that would disable compressors then Reheat is disabled. Jump to end.
16. Verify proper reheat output from RTRM. If 24VAC output is available at the reheat solenoid coil, but the valve is not switching then replace the reheat switchover valve.
Hot Gas Reheat/Dehumidification Sequence of Events:
What is the Sequence of Operation for Reheat/Dehumidification on Voyager II and Precedent Units?
WARNING:
Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.