Bryant 551B Units With Power Exhaust, Service Cleaning, Evaporator Coil, Condenser Coils

Table 29 — Perfect Humidity™ Dehumidification System Sequence of Operation

and System Response — Dual Compressor Units

THERMOSTAT			ECONOMIZER FUNCTION				551B UNIT OPERATION
	INPUT					First Stage			Second Stage
H	Y1	Y2	OAT < Economizer	Economizer	Compressor	Subcooling	Hot Gas	Compressor	Subcooling	Hot Gas
			Set Point		1	Mode	Reheat Mode	2	Mode	Reheat Mode
Off	—	—			Unit Operates Under Normal Sequence of Operation
On	On	On	No	Off	On	Yes	No	On	Yes	No
On	On	Off	No	Off	On	Yes	No	On	No	Yes
On	On	On	Yes	On	On	Yes	No	On	No	Yes
On	On	Off	Yes	On	On	No	Yes	On	No	Yes
On	Off	Off	No	Off	On	No	Yes	On	No	Yes
	LEGEND
OAT	— Outdoor Air Temperature
NOTE: On a thermostat call for W1, all cooling and dehumidification will be off.

F. Units With Power Exhaust

When the outdoor-air damper is modulated open, the two end switches located in the actuator are tripped. The factory settings are: switch no. 1 will close at 30% outdoor air; switch no. 2 will close at 70% outdoor-air. Both switches are field adjustable. As the outdoor-air damper opens, switch no. 1 closes, energizing a double-pole relay that starts fan no. 1. As the outdoor-air damper continues to open, switch no. 2 will close, energizing a double-pole relay that starts fan no.

2.When the outdoor-air damper closes to a point below the fan start points (30% fan no. 1, 70% fan no. 2), the respective fan will be deenergized.

SERVICE

CAUTION: When servicing unit, shut off all elec- trical power to unit to avoid shock hazard or injury from rotating parts.

I. CLEANING

Inspect unit interior at the beginning of each heating and cooling season or as operating conditions require.

A. Evaporator Coil

1.Turn unit power off and install lockout tag. Remove evaporator coil access panel.

2.If EconoMi$er IV or accessory two-position damper is installed, remove economizer or two-position damper by disconnecting EconoMi$er IV plug and removing mounting screws.

3.Slide filters out of unit.

4.Clean coil using a commercial coil cleaner or dish- washer detergent in a pressurized spray canister. Wash both sides of coil and flush with clean water. For best results, back-flush toward return-air section to remove foreign material.

5.Flush condensate pan after completion.

6.Reinstall economizer or two-position damper and filters.

7.Reconnect wiring.

8.Replace access panels.

B. Condenser Coils

Inspect coils monthly. Clean condenser coils annually, and as required by location and outdoor-air conditions.

Clean 2-row coils as follows:

1.Turn off unit power and install lockout tag.

2.Remove top panel screws on condenser end of unit.

3.Remove condenser coil corner post. See Fig. 43. To hold top panel open, place coil corner post between top panel and center post. See Fig. 44.

4.Remove device holding coil sections together at return end of condenser coil. Carefully separate the outer coil section 3 to 4 in. from the inner coil section. See Fig. 45.

5.Use a water hose or other suitable equipment to flush down between the 2 coil sections to remove dirt and debris. Clean the outer surfaces with a stiff brush in the normal manner.

6.Secure the sections together. Reposition the coil sec- tions, and remove the coil corner post from between the top panel and center post. Install the coil corner post and coil center post, and replace all screws.

Fig. 43 — Cleaning Condenser Coil

Fig. 44 — Propping Up Top Panel

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