Led Indicators; Low Voltage Control Wiring - Honeywell HM750A1000 Quick Installation Manual

ELECTRICAL

Low Voltage Control Wiring

Requirements
• 18 AWG solid wire minimum.
• Keep control wires as short as possible.
Control Wiring
There are three separate items to consider with respect to the low voltage
control wiring (Fig. 9):
1. Air Proving switch
2. Humidistat connection
3. Fan interlock wiring
Standard wiring only includes connecting the HUM terminals to the
thermostat/humidistat. For details on other wiring configurations, please refer
to the product manual.
Honeywell recommends that all installations use Air Proving to ensure steam
is only distributed when the furnace fan is active. Air proving terminals are
labeled AP.

LED INDICATORS

Idle - Humidifier has power but no call to humidify.
Filling - Humidifier is on with a call to humidify; the cylinder is filling.
Humidifying - Humidifier is on with a call to humidify. The cylinder should be
producing steam. There may be a delay in actual steam production.
Draining - The cylinder is being drained either from extended idle time to
prevent stagnant conditions, or the drain has been manually activated.
Cylinder - When blinking, the cylinder has a limited time left for use. When
solid, the cylinder life has expired. Replace the cylinder.
Fault - When blinking, there is a fault present. Review the fault code label
behind the humidifier cover for more information, or contact your local service
professional.
Power - If the humidifier is off (no LEDs illuminated), pressing the power
button turns the unit on. If the humidifier is on, pressing the power button
initiates the power down function (cylinder drains then unit shuts off).
Pressing and holding the power button for 5 seconds resets any fault
conditions.
Air Proving Switch
The humidifier will not switch primary power to energize the steam cylinder
unless the AP connections are closed. If no air proving switch is installed,
a jumper shall be installed across these terminals. If a pressure switch
is necessary, consider using the Honeywell Differential pressure switch
(50027910-001).
Humidistat Connection
The humidifier will not switch primary power to energize the steam cylinder
unless the HUM connections are closed. The 24V connections may be used to
power external humidistats (5 VA max.).
Fan Interlock
The collection of terminals on the humidifier control board labeled EXTERNAL
are used to turn an external fan on when there is a call for humidity, if desired.
Main Supply
L1 L2/N GND
Air Proving
AP
AP
Humidistat
24VAC
COM
HUM
HUM
External
GT
RF
2
GF
1 AIR PROVING JUMPER COMES PRE-INSTALLED.
REMOVE JUMPER IF AIR PROVING IS UTILIZED.
2 WIRING FOR FAN INTERLOCK EQUIPMENT (OPTIONAL)
Fig. 9. Control wiring overview.
3
HM750A1000 Advanced Electrode Steam Humidifier
AIR PROVING
(OR JUMPER)
1
THERMOSTAT OR HUMIDISTAT
M36863
HM750
Status
Idle
Filling
Humidifying
Draining
Service
Cylinder
Fault
Power
Drain
Fault Codes In Front Cover
M36945
Fig. 10. LED panel
33-00288EF—01