Trane Tracer manual Heating or Cooling Control Mode Operation, Heating or Cooling Operation

Heating or Cooling Control Mode Operation

Heating or Cooling

Operation

For both single and dual compressor operation, the ZN510 controller cycles the compressor(s) on and off to meet heating or cooling zone demands. The controller uses the

unit capacity and pulse width modulation (PWM) logic along with minimum on/off timers to determine the operation for compressor 1.

With a dual compressor unit, if the desired conditions are not met by

controlling only the first compressor, the controller runs compressor 1 continuously and controls compressor 2 according to PWM logic along with the minimum on/off timers. See Table 6 for heat pump heating or cooling operation.

Table 7: Heat pump heating or cooling operation*

			Capacity
Unit
	0%	Between		Between	100%
		0 and 50%		50 and 100%
		Compressor output is controlled according to pulse width
		modulation (PWM) logic between 0 and 100%. The
	Compressor OFF	controller calculates the compressor on/off times based			Compressor ON
Single compressor		on PWM logic and heating/cooling capacities. The
	continuously.				continuously.
		compressor is controlled on for longer periods as the
		capacity increases and shorter periods as the capacity
		decreases.
Dual (Two) compressors	Both compressors	#1: ON PWM.		#1: ON continuously.	Both compressors ON
	OFF continuously.	#2: OFF continuously.		#2: ON PWM.	continuously.

*Note: No diagnostics present.

Certain heat pump configurations may use one or two compressors for cooling control. Heat pumps use reversing valve control to switch between heating and cooling. The controller supports cooling only configurations and heat pump configurations.

For heat pump configurations, the unit’s reversing valve is energized in cooling and de-energized in heating. For cooling, the reversing valve output is energized simultaneously with the compressor (compressor 1 in two compressor applications). The reversing valve remains energized until the controller turns on the compressor for heating,

simultaneously de-energizing the reversing valve. The reversing valve only changes state when the controller turns on compressor 1.

When a power failure occurs, the reversing valve output defaults to the heating (de-energized) state. To reduce noise due to refrigeration migration after compressor shutdown, the controller does not immediately operate the reversing valve. The reversing valve changes state only when the compressor controls on, except when the controller is in off mode.

For cooling only configurations, no reversing valve is present and the

controller uses the compressor stages for cooling.

Compressor Minimum

ON/OFF Timers

zWhen fan mode = OFF, Com- pressor minimum ON timers are ignored.

zWhen fan mode = AUTO, Com- pressor minimum OFF timers are observed.

zThe diagnostic reset ignores the compressor timers ON and OFF.

zA communicated compressor disabled or unoccupied signal ignores minimum ON times.

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