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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.

ATTENTION INSTALLER:

READ COMPLETE SAFETY INSTRUCTIONS AND INSTALLATION TEMPLATE BEFORE STARTING

FAN POWERED HUMIDIFIER MODEL EHUMD500A

24V

ODT

H

C

R

24 VAC TRANSFORMER (10 VA MINIMUM)

SHUT-OFF

(SADDLE VALVE)

WATER SUPPLY

CORD & PLUG

TO 120 VAC 60 Hz

POWER SUPPLY

CONNECT DRAIN

LINE HERE

BROWN WIRES

NORTH, EAST

OR WEST SIDE

OF HOME

OUTDOOR

TEMPERATURE

SENSOR

ABOVE EXPECTED

SNOW LINE

NOTE:

FOR INSTALLATION IN MANUAL MODE, 
REPLACE OUTDOOR TEMPERATURE 
SENSOR WITH PLASTIC RESISTOR 
CASE AND ATTACH MANUAL FACE 
PLATE. SEE “INSTALLER’S 
GUIDE /AUTOMATIC HUMIDIFIER 
CONTROL, FORM #18-CH31D1-3” 
INCLUDED WITH EACH HUMIDIFIER.

W1

B/C

POWER

BYP
ASS

NOTE

VERIFY THAT SWITCH IS IN 
THE “BYPASS” POSITION.

INSTALLATION OPTIONS

Typical Installation

Alternate Installation

COOLING COILS IN

WARM AIR PLENUM

If humidifier is to be mounted 

adjacent to cooling coils, install 

as shown in relation to coil.

WIRING DIAGRAM  

(SEE STEP 7 ON BACK AND

 “INSTALLER’S GUIDE / AUTOMATIC HUMIDIFIER CONTROL, FORM #18-CH31D1-3”

 FOR DETAILED WIRING INSTRUCTIONS)

90-922

90-1139

RETURN

RETURN

HOT WATER

SUPPLY

SUPPLY

Orientation of Humidifier  

to Cooling Coils

WARNING

1. 

 ELECTRICAL SHOCK HAZARD.

  

120 VAC may cause serious injury from 

electrical shock. 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.

 Sharp edges 

may cause serious injury from cuts. Use care 

when making plenum openings and handling 

ductwork. Use personal protective equipment 

when installing or servicing HVAC equipment.

3. 

 RISK OF SCALDING.

 Water temperature 

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.

SPECIFICATIONS

HUMIDIFIER DIMENSIONS

Width 15

29

32

” 

Height 

(including solenoid valve  

and drain spud)

 18” 

Depth 10

11

32

PLENUM OPENING

14

3

4

”W x 14

5

16

”H

WATER FEED RATE

6 gph

ELECTRICAL DATA

120 VAC-60 Hz, 0.8 AMP

CAUTION

1.  Do not install in attic or crawl areas.
2.  Do not install humidifier where freezing temperatures 

could occur. The water line could freeze and crack 

causing water damage to the home.

3.  Do not install humidifier on the furnace cabinet.
4.  Do not install humidifier on a plenum face where the 

blanked off ends of the cooling coil will restrict air 

movement through the humidifier.

5.  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.

6.  Do not connect the humidifier power cord to multi-speed 

furnace blower motors or blower motors other than 120 

VAC. Premature component failure may result.

7.  When installing Humidifier Control on a downflow 

furnace, ensure blower continues to run after a heat call 

is satisfied to eliminate high temperatures from damaging 

the Control.

8.  Do not install humidifier where water pressure exceeds 

125 psi, since damage to the humidifier may result. Follow 

codes in effect concerning pressure reduction.

9.  Do not install humidifier on the supply plenum where 

static pressure exceeds 0.4 in. wg.

RISK OF PROPERTY AND EQUIPMENT DAMAGE.

BLANKED OFF 

END OF COIL

NOTES

1.  The humidifier is not 

suitable for installation 

on ducts with horizontal 

airflow. Performance will 

be reduced. For such 

applications, use a Large 

Bypass Humidifier.

2.  When installing humidifier 

on a heat pump system, use 

hot water. The heated water 

supplements the reduced 

supply air temperature as 

added heat for evaporation.

3.  If fresh air is piped 

directly into the return air 

duct, it must be installed 

downstream of humidifier.

TEMPLATE MUST BE LEVEL

Trane
Ingersoll Rand
6200 Troup Highway
Tyler, TX 75711-9010

90-1138

COOLING 

COIL

COOLING 

COIL

NOTE:

 FOR COMMUNICATING SYSTEM WIRING DIAGRAMS, 

SEE ENCLOSED INSTALLER’S GUIDE, FORM 18-HE87D1-3.

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