FURNACEBLOWER MOTOR

MODEL 50CURRENT

SENSING RELAY(IF REQUIRED)

24 VAC FURNACEACCESSORY TERMINALS

OR TRANSFORMER(10VA MINIMUM)

SHUT-OFF(SADDLE VALVE)

WATER SUPPLY

YELLOW24V SOLENOIDVALVE WIRES

IMPORTANTUSE 120 VAC POWER SOURCE OTHER THAN FURNACE MOTORCIRCUIT. HOWEVER, THE TRANSFORMER CAN BE POWEREDOFF THE HOT 120 VAC LINE BEFORE IT ENTERS THE FURNACE.• DO NOT WIRE TRANSFORMER INTO FURNACE BLOWER CIRCUIT.

IMPORTANTWHEN MODEL 50 CURRENT SENSING RELAY IS USED:• WIRE MODEL 50 CURRENT SENSING RELAY INTO

24 VAC HUMIDIFIER CONTROL CIRCUIT ONLY!DO NOT INSTALL IN TRANSFORMER PRIMARY CIRCUIT.

CONNECT DRAIN LINE HERE

COMMON

HI

LO

YELLOWWIRES

G

Y

W

C

R

THERMOSTAT

110 VAC

R

C

W

Y

G

FURNACE

OUTDOORTEMPERATURE

SENSOR FORAUTOMATIC

MODE

NORTH, EASTOR WEST SIDE

OF HOME

ABOVE EXPECTEDSNOW LINE

CONTINUOUSLY POWERED24 VAC TRANSFORMER

PROVIDED WITH HUMIDIFIER

CONNECT TOHOT WATER SUPPLY

CONNECT DRAINLINE HERE

OUTPUTSINPUTSPOWER

GWCR H HODT GfA

ADHC TERMINAL STRIP

B

READ COMPLETE SAFETY INSTRUCTIONS AND INSTALLATION TEMPLATE BEFORE STARTING INSTALLATION

This product must be installed by a qualified heating and air conditioning contractor. Failure to do so could result in serious injury from electrical shock.This product must be installed in compliance with all local, state and federal codes.

Proper humidification and humidity control also requires that the home be constructed in accordance with local codes and good building practices.

ATTENTION INSTALLER:

MODEL 500 SERIES HUMIDIFIER

The Model 500 and 500M Aprilaire can beinstalled on either the supply or return

plenum of a forced air handling system andis easily reversible for installation with

right hand or left hand bypass ductconnections. The humidifier dimensionsand serviceability must be considered

when selecting the best location for thehumidifier. Here are 2 examples of many

types of installations.

RESEARCH PRODUCTS CORPORATION • P.O. BOX 1467 • MADISON, WI 53701-1467 • CALL 800/334-6011 • FAX 608/257-4357

RETURN

SUPPLY

S

RETURN

R

SUPPLY

S

Horizontal

Upflow

90-120790-1510

90-1079

WARNING1. ELECTRICAL SHOCK HAZARD.

Disconnect electrical power to thefurnace before starting installation.Failure to do so could result inserious injury from electrical shock.

2. SHARP EDGES HAZARD. Sharpedges may cause serious injury fromcuts. Use care when making plenumopenings and handling ductwork.

3. RISK OF SCALDING. Watertemperature over 125°F can causesevere burns and scald instantly.Shut off the hot water supply beforedisconnecting or tapping into anyhot water supply line.

SPECIFICATIONSHUMIDIFIER DIMENSIONS

Width (including solenoid valve): 15 5⁄8”Height (including drain spud): 13”

Depth: 101⁄4”

BYPASS DUCT OPENING6” diameter

PLENUM OPENING9 1⁄2”W x 9 1⁄2”H

WATER FEED RATE3 gph

ELECTRICAL DATA24 VAC-60 Hz, 0.5 AMP

CAUTION

1. Do not install humidifier where freezing temperaturescould occur. The water line could freeze and crackcausing water damage to the home.

2. Do not install humidifier or bypass connection on thefurnace jacket.

3. Do not install humidifier or bypass connection on aplenum face where the blanked off ends of the coolingcoil will restrict air movement through the humidifier.

4. Do not set humidity level above recommended or torecommended level if condensation exists on insidewindows of any unheated space, as condensationdamage may result. Excess humidity can causemoisture accumulation which can allow the possibilityfor mold growth in the home.

5. Do not connect Model 500 or 500M transformerto blower motor wiring. Premature componentfailure may result.

6. When installing Humidifier Control on downflowfurnace, ensure blower continues to run after aheat call is satisfied to eliminate high temperaturesfrom damaging the Humidifier Control.

7. Do not install humidifier where water pressureexceeds 125 psi, since damage to the humidifiermay result. Follow codes in effect concerningpressure reduction.

8. Do not install humidifier on systems withgreater than 0.4 in. wg pressure differentialbetween supply and return plenums.

RISK OF PROPERTY AND EQUIPMENT DAMAGE.

INSTALLATION OPTIONSRECOMMENDED WIRING DIAGRAMS(SEE STEP 7 ON BACK AND “HUMIDIFIER CONTROL SAFETY AND INSTALLATION INSTRUCTIONS” FOR DETAILED WIRING INSTRUCTIONS)

Model 500MMANUAL CONTROL

Model 500DIGITAL HUMIDIFIERCONTROL

NOTEWhen installing the Aprilaire humidifierwith the Aprilaire Digital HumidifierControl or on a heat pump system, usehot water. The heated water supplementsthe reduced supply air temperature asadded heat for evaporation.

READ COMPLETE SAFETY INSTRUCTIONS AND INSTALLATION TEMPLATE BEFORE STARTING INSTALLATION

TEMPLATE MUST BE LEVEL

– TOP –READ REVERSE SIDE FIRST! READ REVERSE SIDE FIRST!

IMPORTANT! Be sure owner’s manual containing instructions for

operation and warranty information is given to owner in order to avoid

unnecessary calls. Warranty is void unless humidifier is installed by qualified

heating and air conditioning contractor due to possible misapplication of product.

NOTE: BEFORE LEAVING THEJOB SITE, MAKE SURE:

1. Saddle valve is fully open.2. All plumbing connections are

watertight.3. Humidifier functions properly.4. Bypass damper is in proper

position.

Figure 1 Figure 2 Figure 3

10008974 B2205116A 4.10

90-1067 90-1068 90-1069

12

10

2

7

96

11

1

4

3

5

890-1250

FURNISHED ITEMS

ITEMS NOT FURNISHED

Built-in bypass damper24 VAC Transformer

Digital Humidifier Control (Model 500 only)Manual Humidifier Control (Model 500M only)

Humidifier Control Installation InstructionsSaddle valve

Humidifier Installation Template

Mounting screws (sheet metal screws)Water supply line (1⁄4” copper)

Drain line (1⁄2” I.D. hose)Low voltage wireBypass ductwork

Model 50 Current Sensing Relay (if required)

1. Front Cover2. Base3. Feed Tube4. Water Distribution Tray5. Water Panel Evaporator6. Scale Control Insert7. Integral Damper8. Damper Handle9. Drain Spud

10. Hole Plug11. Nameplate12. Solenoid Valve

PARTS LIST

1. Press top & bottom tabs to removecover (1). Pull feed tube (3) out ofdistribution tray (4). Remove Water Panel®

Evaporator assembly. See Figure 1.

2. Humidifier is supplied with bypassduct connection on left. For right sidebypass, swap location of drain spud (9)and cap (10). Twist to remove spudand cap.

3. Position template on supply or returnplenum. Make sure template is level.Allow clearance for drain line and forservicing. Trace template outline. Cut9-1/2” x 9-1/2” opening. Avoid injuryfrom sharp edges.

4. Place humidifier base (2) inopening and secure with 6screws in openings provided.

5. Select location for 6” collaron opposite plenum to minimizelength and number of elbows inbypass duct. Install 6” bypassduct components. Attach duct tohumidifier collar using 2 screwsin openings provided.

6. Insert Water Panel Evaporatorassembly into base. Make surebottom of scale control insert (6)is in drain spud. Snap top ofevaporator assembly into base.

Insert feed tube into distributiontray. See Figure 2. Rotatenameplate (11) if necessary, so itis right side up. Place point bypassdamper handle (8) to “WINTER”(open) for heating season and“SUMMER” for cooling season.

7. Control installation and wiring.Disconnect electrical power tofurnace before wiring control.In order for humidifier to operate,furnace must be on and RH mustbe below set-point of control.Wiring diagrams illustraterecommended method ofdetecting furnace operation.

8. Humidifier will function with cold, hot,softened or unsoftened water. Hot water(140°F max) is strongly recommended toprovide maximum evaporative capacity.Saddle valve provided may be used to tapinto water supply. See installationinstructions on saddle valve package.Saddle valve is designed to be fully openedor closed. Do not use to regulate flow.

9. Run 1/4” copper tubing from saddlevalve to solenoid valve. DOUBLE-WRENCHTO PREVENT LEAKING. See Figure 3.

10. INSTALL DRAIN IN ACCORDANCEWITH LOCAL CODES. Run 1/2” I.D. hosefrom drain spud to floor drain. Make suredrain has constant downward slope and isnot kinked. Do not over-tighten hose clamponto drain spud. Do not use solventadhesive on drain spud.

11. Check humidifier operation. Opensaddle valve and turn control to highestsetting. Turn on furnace. Allow humidifierto run until water flows from drain. Makesure all electrical connections are secureand all plumbing connections are water-tight. Set control to proper setting.

MANUAL HUMIDIFIER CONTROL,MODEL 500M:

Manual Control can be mounted in returnduct or on wall in living space. Knob andcover must be removed to mount control.See wiring diagram for 24V controlconnections.

• For return duct mounting, positiontemplate at least 6” upstream of bypassduct connection or humidifier. Avoidinjury from sharp edges when cuttingopening. Make sure foam gasket is inplace and secure control to duct using2 screws in openings provided.

• For wall-mount, select location that willnot be affected by drafts or heatsources. Remove and discard foamgasket and secure control to wall overwire access opening using screws &anchors provided.

DIGITAL HUMIDIFIER CONTROL,MODEL 500:

• Select location for control on returnduct at least 6” upstream of bypass ductconnection or humidifier. Drill 3/4” holefor sensor. Knob and cover must beremoved to mount control. Place controlon duct with RH sensor extending intoduct opening. Make sure gasket is inplace around sensor cage. Securecontrol to duct using 2 screws inopenings provided.

• See wiring diagrams on template andcontrol instructions for 24 V controlconnections.