HM700A1000
TROUBLESHOOTING
CAUTION
High Voltage Hazard.
Be aware, when troubleshooting, that the humidifier is
powered by high voltage and familiarity with both good
practices and wiring of the humidifier is recommended.
Any troubleshooting that requires opening the cabinet
should be done by qualified personnel.
CAUTION
Burn and Scalding Hazard.
Hot water or steam with a temperature above 120 °F
(49 °C) can cause burns from scalding.
NOTE: Most humidifier faults are not caused by faulty
equipment but rather by improper installation. A
complete fault diagnosis always involves a
thorough examination of the entire system.
Often, the steam hose connection has not been
properly executed, or the fault lies with the
humidity control system.
Symptom
Nothing happens when On/Off
switch is turned on.
Humidifier will not humidify or not
reaching HM700 setpoint
Humidifier has faulted and yellow
LED is flashing
33-00118EFS—03
Table 7. General troubleshooting.
Cause
Fuse blown
Incorrect Voltage
Step Down Transformer not outputting
24VAC
Incorrect primary power jumper
Safety loop open
No demand signal
Capacity has been manually limited
Low conductivity water
No airflow in duct
Software has detected an abnormal
condition
20
TROUBLESHOOTING REQUIREMENTS
• Ensure the installation meets the installation requirements
outlined in the Installation Chapter of this manual.
• Familiarize yourself with the operation of the humidifier by
reading the Operation Chapter of this manual.
• Wiring diagram for specific for your humidifier is installed
on the inside of the humidifier door. A generic copy of the
HM700 wiring diagram is also included at the end of this
chapter for reference purposes.
• When contacting your local representative or Honeywell for
troubleshooting assistance, please ensure the serial
number has been obtained for reference purposes.
The following section provides general guidelines for
troubleshooting the HM700 humidifier and auxiliary
components. For detailed troubleshooting information refer to
the manuals that were provided with the auxiliary equipment
and to Table 8, "Troubleshooting HM700 Faults," on page 22.
Corrective Action(s)
Check inline fuse between transformer and
control board.
Check voltage against spec label and correct.
Replace the transformer.
Check that jumper on high voltage terminal block
is connected between P and terminal
corresponding to supply voltage. See Fig. 16.
Check if there is 24 VAC at terminal 2.
Check wiring and operation of On/Off devices
connected to terminal 1 and 2.
Check jumper is installed in air proving safety
loop, terminal 1 and 8.
Check voltage between terminal 3 and 4. For
demand configuration 35% of full-scale signal
must be present for humidifier to start.
Check Manual Capacity adjustment
potentiometer. Clockwise increases capacity.
Check if yellow LED is on. If operated on low
conductivity water it may take several hours for
the HM700 to reach full output capacity. This is
normal. During this time the humidifier will not
perform any drains and the conductivity of the
water in the cylinder will increase. Conductivity
can be increased more quickly by adding
1/4 teaspoon of salt.
Check that humidifier fan enable (terminals 19-20)
are properly wired to furnace. Check air proving
wired to terminal 8.
Refer to Table 8 on page 22.