READ COMPLETE SAFETY INSTRUCTIONS AND INSTALLATION TEMPLATE BEFORE STARTING INSTALLATION
ATTENTION INSTALLER:
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.
MODEL 500 SERIES HUMIDIFIER
WARNING
CAUTION
SPECIFICATIONS
HUMIDIFIER DIMENSIONS
Disconnect electrical power to the furnace before starting installation. Failure to do so could result in serious injury from electrical shock.
2.SHARP EDGES HAZARD. Sharpedges may cause serious injury from cuts. Use care when making plenum openings and handling ductwork.
3.RISK OF SCALDING. Watertemperature over 125°F can cause severe burns and scald instantly. Shut off the hot water supply before disconnecting or tapping into any hot water supply line.
1.Do not install humidifier where freezing temperatures could occur. The water line could freeze and crack causing water damage to the home.
2.Do not install humidifier or bypass connection on the furnace jacket.
3.Do not install humidifier or bypass connection on a plenum face where the blanked off ends of the cooling coil will restrict air movement through the humidifier.
4.Do not set humidity level above recommended or to recommended level if condensation exists on inside windows of any unheated space, as condensation damage may result. Excess humidity can cause moisture accumulation which can allow the possibility for mold growth in the home.
5.Do not connect Model 500 or 500M transformer to blower motor wiring. Premature component failure may result.
6.When installing Humidifier Control on downflow furnace, ensure blower continues to run after a heat call is satisfiedto eliminate high temperatures from damaging the Humidifier Control.
7.Do not install humidifier where water pressure exceeds 125 psi, since damage to the humidifier may result. Follow codes in effect concerning pressure reduction.
8.Do not install humidifier on systems with greater than 0.4 in. wg pressure differential between supply and return plenums.
Width (including solenoid valve): 15 5⁄8”
Height (including drain spud): 13”
Depth: 101 ⁄4”
BYPASS DUCT OPENING
6” diameter
PLENUM OPENING
9 1 ⁄2”W x 9 1 ⁄2”H
WATER FEED RATE
3 gph
ELECTRICAL DATA
24
RECOMMENDED WIRING DIAGRAMS
(SEE STEP 7 ON BACK AND “HUMIDIFIER CONTROL SAFETY AND INSTALLATION INSTRUCTIONS” FOR DETAILED WIRING INSTRUCTIONS)
INSTALLATION OPTIONS
The Model 500 and 500M Aprilaire can be
installedon either the supply or return
Model 500
DIGITALHUMIDIFIER
CONTROL
R C A B | ODT W/G Cf |
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Model 500M
MANUAL CONTROL
IMPORTANT
USE 120 VAC POWER SOURCE OTHER THAN FURNACE MOTOR
CIRCUIT. HOWEVER, THE TRANSFORMER CAN BE POWERED
OFF THE HOT 120 VAC LINE BEFORE IT ENTERS THE FURNACE.
• DO NOT WIRE TRANSFORMER INTO FURNACE BLOWER CIRCUIT.
24 VAC FURNACE
ACCESSORY TERMINALS
OR TRANSFORMER
(10VA MINIMUM)
plenum of a forced air handling system and is easily reversible for installation with right hand or left hand bypass duct connections. The humidifier dimensions and serviceabilitymust be considered when selecting the best location for the humidifier.Here are 2 examples of many types of installations.
Upflow
SUPPLY
CONTINUOUSLY POWERED
24 VAC TRANSFORMER
PROVIDED WITH HUMIDIFIER
IMPORTANT
DO NOT WIRE TRANSFORMER INTO FURNACE BLOWER CIRCUIT.
(SADDLE VALVE)
WATER SUPPLY
(SADDLE VALVE)
WATER SUPPLY 
COMMON |
YELLOW |
RETURN 
NORTH, EAST |
OR WEST SIDE |
OF HOME |
OUTDOOR |
TEMPERATURE |
SENSOR OR |
MANUAL MODE |
RESISTOR |
ABOVE EXPECTED |
SNOW LINE |
24 VAC FURNACE ACCESSORY TERMINAL
COMMON
YELLOW 24V SOLENOID VALVE WIRES
CONNECT DRAIN LINE HERE
CONSULT FURNACE MANUFACTURER FOR VOLTAGE AND OPERATION PARAMETERS OF ACCESSORY TERMINALS.
TERMINALS MAY BE LABELED: “HUM”, “ACC” OR “EAC”
NOTE: IF 120V, INSTALL 24V TRANSFORMER.
NOTE: SEE CONTROL INSTRUCTIONS FOR OTHER
HI |
| 24V SOLENOID |
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| VALVE WIRES |
LO |
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FURNACE |
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BLOWER MOTOR |
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| MODEL 50 |
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| CURRENT | CONNECT DRAIN LINE HERE |
| SENSING RELAY | |
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IMPORTANT
WHEN 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.
Horizontal
RETURN
SUPPLY
NOTE
When installing Aprilaire humidifier on a heat pump system, use hot
WIRING OPTIONS.
water. The heated water supplements the reduced supply air temperature as added heat for evaporation.
RESEARCH PRODUCTS CORPORATION • P.O. BOX 1467 • MADISON, WI
