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HM750A1000

33-00289—01

6

LOCATION

Mount on a suitable wall or vertical surface. Do not sit the 
unit on the floor. Allow clearances required for plumbing 
and electrical connections. Clearance dimensions shown 
are for reference only and are the minimum required for 
maintenance of the humidifier.

Fig. 3. Clearances for the HM750.

Consult local and national codes before final location and 
installation. Honeywell does not accept responsibility for 
installation code violations.

• Install only in areas with ambient temperature 41 to 

104 °F (5 to 40 °C) and relative humidity 5 to 95 %, 
non-condensing.

• Humidifier must be installed below the steam 

distributor nozzle. Take care to provide proper steam 
line routing.

• DO NOT locate the humidifier any further than 

absolutely necessary from the steam distributor nozzle 
location as net output will be reduced as a result of heat 
loss through the steam line.

• When possible, mount the HM750 humidifier at a 

height convenient for servicing.

NOTE:

Do not mount on surfaces above 176 °F (80 °C), 
where freezing can occur, vibrating surface, or floor.

Fig. 4. Distributor nozzle installed vertically

in a horizontal duct.  (Remote mount)

Steam Nozzle Location

Whether the humidifier is being installed directly on the 
air duct or remotely, the location of the distributor nozzle 
in the air duct should follow the subsequent rules:

Fig. 5. Distributor installed horizontally (side mount)

in a horizontal duct. (Remote mount)

Measurements in inches (mm).

Fig. 6. Distributor nozzle installed horizontally 

in a vertical duct. (Remote mount)

24 INCHES (610 MM)

4 INCHES (102 MM)

1 INCH
(25 MM) 

41˚ - 104˚ F
(5˚ - 40˚ C)

0-95%
NON CONDENSING

M36860A

1 INCH (25 MM) IF WIRED BEFORE MOUNTING.
36 INCHES (914 MM) FOR WIRING ACCESSIBILITY.

1

1

AIR FLOW 

1/2 DUCT WIDTH 

M37234

AIR FLOW 

8 (204)

MINIMUM

4.5 (114)

M37232

MINIMUM CLEARANCE TO TOP OF DUCT.

1

1

AIR FLOW 

1/2 DUCT
WIDTH

M37233

Summary of Contents for HM750

Page 1: ...ons 33 00289 this document Annual Operation and Maintenance Reminder Tools Needed Flat head screwdriver Phillips screwdriver Wrench Copper pipe optional Level Hole saw Humidifier Configuration The HM750 is configured at the factory to operate under most conditions without the need to change its configuration NOTE Because the humidifier is factory configured for optimal performance Honeywell strong...

Page 2: ...the steam outlet Steam lines must be installed so that no restriction can produce backpressure in the humidifier Do not mount outdoors without protection against rain snow condensation or equivalent CAUTION Water quality The Honeywell HM750 requires a cold water connection from your home s main water supply between 15 100 PSIG A throttle valve may be necessary and a water shut off valve is recomme...

Page 3: ...nerals in the water will adhere to the cylinder electrodes The humidifier will automatically fill to a higher water level to maintain full capacity during the life of the cylinder Eventually because of scale formation it will no longer be possible for the humidifier to reach its full capacity The HM750 software monitors this condition and when detected will stop operating and the Cylinder LED will...

Page 4: ...rements Table 3 AHRI Recommended Humidity in US gallons per day Table 4 Steam humidifier s necessary for application a a In the table above 11 GPD indicates a steam humidifier configured to run on 120 V and 22 GPD indicates a steam humidifier configured to run on 240 V Construction Type 8 000 ft3 12 000 ft3 16 000 ft3 20 000 ft3 24 000 ft3 32 000 ft3 40 000 ft3 Tight 3 3 5 0 6 7 8 3 10 0 13 4 16 7...

Page 5: ...TIONAL OFF ON HOT HOT GROUND OFF ON 120 VAC 4 102 1 25 1 25 4 102 1 25 IF WIRED BEFORE MOUNTING 36 INCHES 914 FOR WIRING ACCESSIBILITY 240VAC 120VAC HUMIDIPRO H6062 AIR PROVING OR JUMPER 24VAC COM HUM HUM AP AP Air Proving Humidistat 1 1 THERMOSTAT OR HUMIDISTAT 3 4 19 OD 1 4 LDPE OR COPPER WATER LINE ALWAYS INSTALL A WATER SHUT OFF VALVE USE 1 2 IN OD COPPER TO WITHIN 4 FT 1 2 M OF HUMIDIFIER AIR...

Page 6: ...t will be reduced as a result of heat loss through the steam line When possible mount the HM750 humidifier at a height convenient for servicing NOTE Do not mount on surfaces above 176 F 80 C where freezing can occur vibrating surface or floor Fig 4 Distributor nozzle installed vertically in a horizontal duct Remote mount Steam Nozzle Location Whether the humidifier is being installed directly on t...

Page 7: ...n the supply side of ductwork As shipped the HM750 is configured with a steam guide for remote mounting The steam outlet points upwards and is only used when the humidifier is installed remote to the air supply duct The steam distributor nozzle should be installed as close as possible to the humidifier to a maximum of 15 ft 4 6 m The HM750 is supplied with a 5 ft steam hose A 15 ft hose is availab...

Page 8: ...t Cover CONNECT STEAM HOSE TO CYLINDER M37204 TO DRAIN OBSTRUCTION 12 305 MINIMUM RADIUS SUPPORT BRACKETS USE FULL SIZE CONDENSATE TEE AT LOW POINT SLOPE LINES UP TO T AND IMMEDIATELY AFTER IT HOSE WILL SOFTEN OVER TIME PROPER SUPPORT IS NECESSARY 1 4 102 MINIMUM 12 305 MINIMUM 1 HM750 Status Service Power Idle Filling Humidifying Draining Cylinder Fault Drain Fault Codes In Front Cover 12 305 MIN...

Page 9: ...ier see Fig 13 The steam hose should maintain an inclination of at least 4 inches 10 cm of rise for every 12 inches 30 cm of run CAUTION Do not remove the cover when the humidifier powered 1 Remove the humidifier cover and pull out the cylinder Insert the top screw until 1 4 in 6 mm is exposed Hang the humidifier via its keyhole on the screw head see Fig 12 2 After making sure the humidifier is le...

Page 10: ...the duct mount nozzle 4 Secure the steam hose to the duct mount nozzle with the hose clamp Do NOT overtighten or the duct mount nozzle could be damaged 5 Reconnect the cylinder plugs and high water sensor plug to the cylinder pins MOUNT HUMIDIFIER ON DUCT 1 Using the duct mount template supplied with the humidifier locate the template on the side of the duct where the humidifier will not interfere...

Page 11: ...vide free and easy draining A restricted drain can cause cylinder water to over concentrate and result in poor operation Drain line must be continuously sloped down from unit If a drain is not located near the humidifier use a condensate pump rated for hot drain water Connecting the Water Supply Line Connect water supply line Copper or LDPE supplied with equipment to the supply connection Fig 18 T...

Page 12: ...5 amp circuit breaker All wiring must be done per governing electrical codes Failure to do so will void the product warranty The use of electric cord plugs can cause overheating and result in risk of damage to property and or personal injury Wiring Procedure 1 Install a disconnect switch between the humidifier and the circuit breaker as shown in Fig 21 and Fig 22 optional 2 Route the power supply ...

Page 13: ...e is a call for humidity Fig 23 Wiring the steam humidifier with a digital thermostat Fan Interlock Wiring with HumidiPRO When distributing steam into a duct there could be a call for humidity when there is no air flow The HM750 with HumidiPRO control or some other thermostat can be used to enable a fan on a call for humidity If using another thermostat consult that control s manual for wiring ins...

Page 14: ... HM750 only these two wires are necessary to control humidity Be sure to configure the control to force fan on with a call for humidity or run on a heat cycle if the fan enable wiring is not used HVAC THERMOSTAT R C U U S S G Y W R Rc G Y W R C M37198 OUTDOOR SENSOR NOTE SPDT RELAY IS NECESSARY TO PREVENT ENERGIZING THE Y TERMINAL IF THE THERMOSTAT DOES NOT ISOLATE Y AND G SPDT RELAY COM NC NO AIR...

Page 15: ...f applicable the high limit humidistat This will enable a call for humidity 6 If the fan enable relay on the control board is used the green LED will continue to flash until the air proving closes Once the air closes the flashing green LED will become solid and the humidifier will start steam production 7 When the external humidistat calls for humidity and the air proving terminals are closed the ...

Page 16: ... Excess Current fault 2 flashes Fill Drain fault 3 flashes Insufficient Current fault 4 flashes PCB fault 5 flashes Wrong Voltage Selector fault See the Troubleshooting section for more information MAIN BUTTON Power Drain When primary power has been wired to the humidifier the Power Drain button must be pressed in order to enable steam generation When the user so decides the humidifier may be turn...

Page 17: ...midifier Fill cup Provides an air gap for backflow prevention Fill valve Controls flow of water into humidifier High water sensor Used to detect maximum water level in cylinder Power Drain button Used to turn the humidifier on or off Note that before the humidifier turns off the water in the cylinder is drained CAUTION The unit will still be powered internally even after being shut down Steam cyli...

Page 18: ...ric current leak is detected In all cases proper cleaning of the drain valve is recommended HOSE CONNECTIONS Inspect annually clean as necessary NOZZLE DUCT OR REMOTE Inspect annually clean as necessary Extended Shutdown Should it be required to disconnect power to the humidifier for a period of extended shut down the following procedure shall be followed 1 Press the Power Drain button 2 Wait unti...

Page 19: ...nd the cylinder LED will be on constantly no flashing At this point the cylinder must be replaced The steam cylinder is disposable and must be replaced at end of cylinder life Cylinder life is dependent on water supply conditions and humidifier use Always clean the drain valve before installing a new cylinder Scale from the spent cylinder may have fallen into the drain valve and could prevent its ...

Page 20: ...nder plugs from the cylinder pins by pulling vertically 6 Using a flat screwdriver or 5 16 in nut driver loosen the hose clamp closest to the cylinder 7 Pull the cylinder away from the steam hose to disengage When free of steam hose lift the cylinder out 8 Some water may remain in the cylinder even after fully draining Have a cloth available to absorb any water Fig 29 Removing the cylinder IMPORTA...

Page 21: ...he core 6 Using an adjustable wrench unscrew the core counterclockwise from the drain valve body 7 Carefully remove the core assembly this includes the plunger and return spring from the plastic drain valve body The plunger seal rubber stop can be cleaned using a plastic brush tooth brush or damp cloth Do NOT use a metal brush or chemical cleaning agents as this could damage the part Fig 30 Removi...

Page 22: ...d personnel To protect the user and the control board the control board is mounted in a red electrical compartment housing 1 Disconnect main power at the external disconnect 2 Using a flat screwdriver turn the lock on the humidifier s front cover 90 counterclockwise to release Rotate the base of the cover outwards 6 inches then lift upwards to remove 3 Use a flat screwdriver to loosen the retainin...

Page 23: ... the wiring to the solenoid See Fig 32 6 Remove quick connect fitting from inlet valve 7 Grip the inlet valve and pull forward as far as possible 8 Inside the humidifier bend the hose attached to the inlet valve up as shown in Fig 33 9 Using pliers move the clamp up the hose away from the valve to release its hold Slide the hose off the valve Some remaining water in the hose will spill out Have a ...

Page 24: ...e located beside transformer Incorrect voltage Check voltage against specification label and correct Step down transformer not outputting 24 VAC Replace the circuit board Incorrect primary power jumper Check that the on board voltage selection jumper is installed correctly If 240 VAC power was supplied to a unit where the voltage selection jumper was set to 120 VAC the circuit board will need to b...

Page 25: ...rmal operation None Cylinder solid Cylinder end of life Normal operation Replace cylinder Fault 1 flash Excess Current Current has exceeded 130 of max Drain blocked water over concentration Clean the drain line Drain solenoid not energized water over concentrated Check and correct wiring to drain valve Filling too fast wrong fill valve Fill valve may be defective replace if necessary Water supply ...

Page 26: ...CB Error The control board detects current draw when the humidifier is in standby mode Replace circuit board Fault 5 flashes Wrong Voltage Selection VOLTAGE SELECTION jumper on control board is incorrectly set If 240VAC is supplied to the humidifier but the VOLTAGE SELECTION jumper is set to 120VAC the control board will fail and need to be replaced If 120VAC supplied to the humidifier but the VOL...

Page 27: ...TAT AIR PROVING SW GT RF GF IDLE LED FILLING LED HUMIDIFYING LED DRAINING LED CYLINDER LED FAULT LED ON OFF DRAIN FAULT RESET BUTTON BLACK BLUE RED YELLOW FILL VALVE DRAIN VALVE FAULT CODES NUMBER OF FLASHES INDICATES FAULTS TO CLEAR FAULTS PRESS AND HOLD POWER BUTTON FOR FIVE SECONDS 1 EXCESSIVE CURRENT 2 FILL DRAIN ERROR 3 INSUFFICIENT CURRENT 4 PCB ERROR 3 WRONG VOLTAGE SELECTION FLASHING IDLE ...

Page 28: ...at the defect was caused by damage which occurred while the product was in the possession of a consumer Honeywell s sole responsibility shall be to repair or replace the product within the terms stated above HONEYWELL SHALL NOT BE LIABLE FOR ANY LOSS OR DAMAGE OF ANY KIND INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING DIRECTLY OR INDIRECTLY FROM ANY BREACH OF ANY WARRANTY EXPRESS OR I...

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