25
PROBLEM
POSSIBLE CAUSE
RECOMMENDED ACTION
Humidifier will not
heat.
Control transformer
Reset control transformer circuit breaker.
Humidistat is not calling
Set humidistat to call. Inspect for faulty humidistat.
Safety controls open
Check safety controls, airflow switch, high limit
humidistat, etc.
Low water cutoff
Check at board 32 and 33. Measure 0 Volts for closed switch,
approximately 2.5 Volts for AC open switch.
Humidifier will not fill.
No water pressure at valve
Check manual water supply valve for minimum 25 psi
(175 kPa) water pressure.
Plugged fill valve
Check fill valve inlet.
Humidifier does not
stop filling.
Open drain valve
Obstruction in drain valve will not allow complete closure.
Clean or replace valve.
Manual drain valve not closed
Close drain valve.
Fill valve stuck open
Check for foreign matter in valve, water-logged float, broken
float arm, or worn valve stopper.
Reduced or no output
even though water is
at the proper level
Heater malfunctioning
Verify that proper voltage is being applied to heaters. Check
heater amp draw and compare to wiring diagram ratings.
Malfunctioning control system
Replace heater contactor if not functioning. Verify auxiliary
limit controls (humidistat, airflow proving switch, etc.) and
reset, replace or calibrate as needed.
Troubleshooting guide for DI water models
HUMIDI-TECH
®
TROUBLESHOOTING GUIDE
VM99-C-0302-M-0302.pdf 25
11/19/2009 9:51:09 AM
