Aprilaire 1150 Installation, Operation And Maintenance Manual page 40

Problem Possible Cause
The On/Off light on Mineral buildup or
the display panel is
oxidation on probe rods
blinking slowly (one
Deterioration of probe rod
blink per second)
assembly
The On/Off light on Probe is wired incorrectly
the display panel is
blinking rapidly (10
blinks per second)
Deterioration of probe rod
(illogical probe fault)
assembly
Chamber water is foaming .
No remote fault
Field wiring not installed
indication (drain fault,
Remote fault relay is not
fill fault, illogical
switching .
probe fault)
Field-supplied remote fault
Note: This is an
indicator lamp is burned out .
optional connection
System fan/blower System fan/blower power
doesn't operate
is off
System fan/blower is not
wired to internal controller
board
Internal controller board is
configured for remote fault
indication
Humidifier does not Nonexistent supply voltage
energize; chamber to humidifier
does not heat up
Nonexistent control voltage • C heck for proper supply voltage per wiring diagram.
Humidifier
over-temperature
thermostat is open .
Non-resettable over-
temperature thermostats
(in power lines to heaters)
are open .
Reduced or no output Malfunctioning control
(even though water system
level is correct)
Heater malfunctioning
40
Action
• R emove probe assembly and clean probe rods; reset power to clear warning.
• R eplace probe rod assembly.
• V erify wiring; see wiring diagram.
• V erify that probe wires are routed separately from high voltage wires to avoid interference.
• V erify the green and yellow ground wire is connected to the subpanel and to the C terminal.
• R eplace probe rod assembly.
• C lean chamber.
• P rovide field wiring to a remote fault indicator from NO, O, NC control terminal block.
• C heck relay continuity NO, O, NC control terminal block for contact closure.
• C heck if lamp by others is burned out; replace if needed.
• T urn power supply on.
• C heck wiring diagrams on pages 12, 13, and 14 for wiring to NO, O, and NC terminals.
• S lide switch S2 position 9 must be in 'off' position. See page 15 for more information.
• C heck main line fuse.
• C heck main line safety switch.
• V erify relay/contactor electrical plug is fully engaged.
• V erify proper wiring of multi-tap transformer.
• V erify transformer electrical plug is fully engaged.
• C heck for control circuit voltage, 24 VAC. If voltage is not present at H and C, check transformer
circuit breaker .
• R eset if needed by pressing On/Off switch on display panel.
• R eset manual over-temperature switch located above heater on humidifier cover.
• R eset manual switch located above heater on humidifier cover.
• V erify relay/contactor and transformer electrical plugs are fully engaged.
• R eplace non-resettable thermostats.
• C heck all components for over-temperature damage.
• D etermine cause of dry fire by checking for a frozen relay/contactor or a probe assembly
malfunction and remedy before restarting humidifier .
• C heck if auxiliary limit controls are not allowing system to operate, e.g., high humidity limit
switch, airflow proving switch, etc.) Reset, replace, or calibrate as needed.
• C heck if the heater over-temperature thermostat has tripped. Reset if necessary.
• C heck if the non-resettable over-temperature thermostats have tripped. Replace if necessary.
• V erify that relay/contactor and transformer electrical plugs are fully engaged.
• V erify that proper voltage is being applied to heaters.
• C heck heater amperage.
• I f heater power device is not functioning, replace.