Dometic Q3, Qht (digital controls for direct expansion systems)

Seawater Low Limit Adjustment (Optional; Factory Default: 40°F) If the optional seawater sensor is connected to the control board, this feature allows the system to switch from reverse-cycle heat to electric heat (if an auxiliary electric heater is installed and enabled) if the seawater temperature drops below 40°F (4.

1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 FAULT AND ERROR MESSAGESPage 15
2. READ THIS MANUAL BEFORE PROCEEDING . . . . . . . . . 1 HIGH-PRESSURE SHUTDOWN (HI / PS)Page 15
3. CONTROLS OVERVIEW . . . . . . . . . . . . . . . . . . . . . . . . 1 In Cool ModePage 15
4. FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 In Heat ModePage 15
5. HOW IT WORKS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 LOW-PRESSURE SHUTDOWN (LO / PS)Page 15
6. The Importance of Seawater Temperature . . . . 1 In Cool ModePage 15
7. Power Interruptions . . . . . . . . . . . . . . . . . . . . . . 2 In Heat ModePage 15
8. DESCRIPTION OF THE CONTROLS . . . . . . . . . . . . . . . . 3 LOW-VOLTAGE SHUTDOWN (LO / AC)Page 15
9. END USER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 INITIAL SYSTEM START UPPage 16
10. NORMAL HEATING OR COOLING CYCLEPage 5
11. TROUBLESHOOTINGPage 17
12. REVERSING VALVE OPERATIONPage 5
13. GENERAL SYSTEM TROUBLESHOOTINGPage 17
14. INSTALLING THE DISPLAY PANEL . . . . . . . . . . . . . . . 5 DIGITAL-CONTROLS TROUBLESHOOTINGPage 20
15. MOUNTING THE DISPLAYPage 5
16. MAINTENANCE OF SYSTEM COMPONENTSPage 21
17. MOUNTING THE SENSORSPage 5
18. CONDENSATE DRAINSPage 21
19. Ambient Temperature Sensor - requiredPage 5
20. RETURN-AIR FILTERPage 21
21. Seawater Temperature Sensor - optionalPage 5
22. Outside Air Temperature Sensor - optional . . . 6 SEAWATER CONNECTIONSPage 21
23. Humidity Sensor - optional . . . . . . . . . . . . . . . . 6 SEAWATER PUMPPage 21
24. OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 SEAWATER STRAINERPage 22