General Filters MHX3C User Manual

Please Read And Save These Instructions
• Installationbyanyoneotherthanaqualiedcontractorvoidsthewarranty.
• Productdesignedforresidentialinstallationonly.Commercialinstallationvoidswarranty.
• Modicationoralterationofproduct,parts,installationinstructionsorlocalsafetycodesvoidswarranty.
• Readourfullwarrantypolicyattheendofthisdocument.
Breathe Healthier
About the MHX3C Digital Humidistat
The MHX3C control provides low voltage control of most humidiers. The humidistat uses a SPDT switch and is designed
for wall mounting in the living area or mounting on the return air duct.
WARNING! Always TURN OFF POWER TO THE HVAC SYSTEM prior to installing or servicing the humidier or
humidistat. Improper operation can result in over or under humidication. Improper voltage can cause malfunction or
damage to the control. All local building and electrical codes must be followed. The technical specications for this
product and the contents of the user manual are subject to change without notice.
WARNING! Do not set relative humidity too high during cold weather. Over humidication can result in condensation,
structural damage and mold.
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Canadian General Filters, Ltd.
400 Midwest Rd.
Toronto, ON M1P3A9 Canada
Toll Free: (888) 216-9184
www.cgfproducts.com
General Filters, Inc.
43800 Grand River Avenue
Novi, Michigan 48375
Toll Free: (866) 476-5101
www.generalaire.com
MHX3C Humidistat
(GFI #7038)
Installation Manual
GENERAL FILTERS
INCORPORATED

General Filters MHX3C Specifications

General

Brand	General Filters
Model	MHX3C
Category	Humidistats
Language	English

Summary

Please Read And Save These Instructions

About the MHX3C Digital Humidistat

Specifications

MHX3C Locations

WALL MOUNTING INSTRUCTIONS

Instructions for mounting the humidistat on a wall, including gasket usage and wiring.

DUCT MOUNTING ON THE RETURN AIR

Instructions for mounting the humidistat on a return air duct, including gasket usage and wiring.

Wiring Diagrams

DIAGRAM 1: Wiring 24V Bypass Humidifier

Shows wiring for a 24V bypass humidifier using the MHX3C.

DIAGRAM 2: Wiring High Limit Humidistat

Illustrates wiring for high limit humidistat function with Elite Steam humidifiers.

DIAGRAM 3: Wiring 120V Power Humidifiers (Furnace Supplied)

Wiring for 120V power humidifiers connected to furnace supply.

DIAGRAM 4: Dehumidifier

Wiring diagram for using the MHX3C as a dehumidistat.

DIAGRAM 5: Wiring 120V Power Humidifiers (Constant Supply)

Wiring for 120V power humidifiers with a constant 120V supply.

Troubleshooting

Humidifier turns on and off repeatedly

Addresses issues with the humidifier cycling on and off too frequently.

Humidifier operates continuously

Explains why the humidifier might run constantly and how to fix it.

No humidifier operation in "ON" mode

Troubleshooting steps for when the humidifier does not turn on.

Ideal humidity is not achieved

Diagnoses problems when the desired humidity level is not met.

Using the MHX3C

Limited Warranty