NA1552Users' Guide
Technique Index:
Temperature display range: -50~125C(step 0.1C)
Temperature setting range: -45~120C
Power supply: 12VAC
Operation Environment: Temperature -10C~45C, humidity≤ 85%.
Relay contact capability: 2A/250VAC (Pure resistive load)
Temperature sensor: NTC R25=5kΩ , B (25/50) =3470K
Executive standard: Q/320585 XYK 01 (NA1552-CHTFAX)
Main Function and Control Logic:
Two channels: One is at the backwater inlet, as the temperature controlling signal. One is at the water outlet, used for frostbite preventing.
Five output channels: Compressor, condensate fan, cross shuttle valve, water pump, alarm output.
Five switching value inputs (passive point signal): High pressure protection, low pressure protection, overload protection, deficient phase protection, water pressure switch.

Control Logic:
1. Water pump
The water pump can be set into two modes of "Controlled mode" and "Natural mode". The water pump is always running after the system is on, and it will stop when the system is off or it is in the state of water lack error. If the controller doesn't receive the water pressure signal after the water pump has been running for 1 minute, it will stop running and give an alarm (water lack alarm). If the water pressure signal has disappeared for over 5 seconds when the water pump is running, it will stop running and give an alarm (water lack alarm).

2. Startup
The controller will first check the water pressure signal after reaching the startup temperature and the condensate fan will be turned on if the water pressure signal is normal, also the compressor starts upafter delaying for 3 seconds and the cross shuttle valve will start up with the compressor according to the operating mode. In addition, the compressor has the function of delay protection, and the functioncan ensure that the compressor must start up again after 3 minutes (The delay time is adjustable).
3. Halt
1) Normal halt:
2) Error halt:
3) Preventing frostbite halt:
4)Shut down:

4. Operating mode
It contains three kinds of mode: "refrigeration", "heating", constant temperature".
1)Refrigerating mode:
2)Heating mode:
3)Constant temperature mode:
5. Fault protection and alarm
Pressure: Always open, the controller will stop when the point is close, corresponding indicator light will flash and the alarm output is given at the same time.
Deficient phase: Always open, the controller will stop when the pointis close, corresponding indicator light will flash and the alarm output is given at the same time.
Overload: Always open, the controller will stop when the point is close, corresponding indicator light will flash and the alarm output is given at the same time.

Water lack: Always open, the point will close when the water pressurenormal, after the water pump delayed, it will stop if the point is not close, corresponding indicator light will flash and the alarm output is given at the same time.

Temp sensor error: The unit stops when the temperature sensor is openor short, the controller gives the error code (the nixietube is showing "A01"), and at the same time gives a alarm output.
Preventing frostbite sensor error: The unit stops when the frostbite preventing sensor is open or short, the controller gives the error code (the nixietube is showing "A02"), and at the same time gives a alarm output.
Defrosting sensor error: The unit stops when the defrosting sensor isopen or short, the controller gives the error code (the nixietube is showing "A03"), and at the same time gives a alarm output.
Preventing frostbite alarm: The unit stops when the temperature of the water outlet is below 3C, the controller gives the error code (the nixietube is showing "A04"), and the unit will run again when the temperature of the water outlet is above 5C.