Aprilaire 1952, 1953 & 1972 service manual Install the Unit Base, Make Electrical Connections

INSTALL THE UNIT BASE

1.Using the Unit Base as a guide, mark the locations for the lamp and mounting holes on the rooftop unit cabinet.

2.Carefully inspect the inside of the rooftop unit and make sure that no damage to any components will occur as a result of drilling the holes.

3.Drill hole for the lamp using a 2 in. hole cutter. At the mounting hole locations, use 3/32 in. drill bit to make pilot holes for mounting screws.

4.Apply weatherproof sealant (not provided) to the side of the Unit Base that is in contact with the rooftop unit housing. Mount the Unit Base to the rooftop unit using #10 sheet metal screws.

MAKE ELECTRICAL CONNECTIONS

1.Verify power to the HVAC equipment is shut off. Determine where the power for the unit will come from. The units can use any voltage from 120 VAC up to 277 VAC (single phase), 60 Hz. The ballast automatically adjusts to whatever voltage is supplied in that range. The units must be wired such that the disconnect switch of the air handler is also the disconnect switch for the UV lamp. Additionally, to prevent accidental exposure to UV germicidal light, it is recommended that safety interlock switches (not provided) be installed on any access panel door within view of the UV lamp. See Figure 3 for Model 1952/1953 wiring diagram.

2. Use the hole in the bottom of the

Unit Base and a corresponding

hole through the rooftop unit

FIGURE 3 – Model 1952/1953 Wiring Diagram

housing for the electrical wiring.

Be certain the area in the rooftop

unit where you intend to drill and

cut is free of any obstructions or

components that would be

damaged by the installation or

interfere with the installation.

3. If space limitations prevent

running the wires through the

hole in the bottom of the Unit

Base, drill holes in the side of

the Unit Base as well as the

rooftop housing for watertight

conduit connectors. Install the

connectors and run conduit from

the Unit Base to the rooftop

unit penetration.

4. Run wiring from the power

source through the conduit, if

applicable, and into the Unit.

Connect wiring to terminals

provided. Refer to wiring

diagram, Figure 3. Unit must

Interlock switches (not provided) recommended for all access panel doors

Black

White

Green

120VAC to 277VAC Power Source

Blue (2)	Yellow (2)
	NOT USED
Red (2)
Lamp Socket
Interlock Switch
	Ballast
3A Fuse
Black	Green
White
	Ground

be grounded.

90-753

5.Shield non-metallic components (such as electrical wires and fan belts) that receive direct or reflected UV radiation with aluminum tape, sheet metal, or conduit.

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