Bryant 581B installation instructions Perfect Humidity Normal Design Cooling Operation

Hot Gas Reheat Mode

When the humidity levels in the space require humidity con- trol, a hot gas solenoid valve (specific to hot gas reheat mode only) will open to bypass a portion of hot gas refrigerant around the condenser coil (see Fig. 43).

This hot gas will mix with liquid refrigerant leaving the con- denser coil and flow to the subcooling/reheat dehumidification coil. Now the conditioned air coming off the evaporator will be cooled and dehumidified, but will be warmed to neutral conditions (72 F to 75 F) by the subcooling/reheat dehumidification coil.

The net effect of the rooftop when in hot gas reheat mode is to provide nearly all latent capacity removal from the space when sensible loads diminish (when outdoor temperature conditions are moderate). When in hot gas reheat mode, the unit will operate to provide mostly latent capacity and extremely low sensible heat ratio capability.

Similar to the subcooling mode of operation, hot gas reheat mode operates only when the outside-air temperature is warmer than 40 F. Below this temperature, a factory-installed outside air temperature switch will lock out this mode of operation.

See Table 30 for the dehumidification system sequence of operation.

Fig. 41 — Perfect Humidity™ Normal

Design Cooling Operation

Fig. 42 — Perfect Humidity Subcooling

Mode Operation

Fig. 43 — Perfect Humidity Hot Gas

Reheat Mode Operation

Table 30 — Perfect Humidity Dehumidification System Sequence of Operation and

System Response — Single Compressor Unit

THERMOSTAT INPUT			ECONOMIZER FUNCTION				581B UNIT OPERATION
H	Y1	Y2	OAT. < Economizer Set Point	Economizer		Comp. 1	Subcooling Mode	Hot Gas Reheat Mode
Off	—	—			Normal Operation
On	On	On	No		Off	On	Yes	No
On	On	Off	No		Off	On	Yes	No
On	On	On	Yes		On	On	Yes	No
On	On	Off	Yes		On	On	No	Yes
On	Off	Off	No		Off	On	No	Yes
	LEGEND				NOTE: On a thermostat call for W1, all cooling and dehumidification will
OAT — Outdoor Air Temperature					be off.

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