Aprilaire 1150 - Manual (Page 33)

Problem Possible Cause Action
The On/Off light on
the display panel is
blinking slowly (one
blink per second)
Mineral buildup or
oxidation on probe rods
• Remove probe assembly and clean probe rods; reset power to clear warning.
Deterioration of probe rod
assembly
• Replace probe rod assembly.
The On/Off light on
the display panel is
blinking rapidly (10
blinks per second)
(illogical probe fault)
Probe is wired incorrectly • Verify wiring; see wiring diagram.
• Verify that probe wires are routed separately from high voltage wires to avoid interference.
• Verify the green and yellow ground wire is connected to the subpanel and to the C terminal.
Deterioration of probe rod
assembly
• Replace probe rod assembly.
Chamber water is foaming. • Clean chamber.
No remote fault
indication (drain fault,
fill fault, illogical
probe fault)
Note: This is an
optional connection
Field wiring not installed • Provide field wiring to a remote fault indicator from NO, O, NC control terminal block.
Remote fault relay is not
switching.
• Check relay continuity NO, O, NC control terminal block for contact closure.
Field-supplied remote fault
indicator lamp is burned out.
• Check if lamp by others is burned out; replace if needed.
System fan/blower
doesn’t operate
System fan/blower power
is off
• Turn power supply on.
System fan/blower is not
wired to internal controller
board
• Check wiring diagrams on pages 9 and 10 for wiring to NO, O, and NC terminals.
Internal controller board is
configured for remote fault
indication
• Slide switch S2 position 9 must be in ‘off’ position. See page 11 for more information.
Humidifier does not
energize; chamber
does not heat up
Nonexistent supply voltage
to humidifier
• Check main line fuse.
• Check main line safety switch.
• Verify contactor electrical plug is fully engaged.
Nonexistent control voltage • Check for proper supply voltage per wiring diagram.
• Verify proper wiring of multi-tap transformer.
• Verify transformer electrical plug is fully engaged.
• Check for control circuit voltage, 24 VAC. If voltage is not present at H and C, check transformer
circuit breaker.
• Reset if needed by pressing On/Off switch on display panel.
• Reset manual over-temperature switch located above heater on humidifier cover.
Humidifier
over-temperature
thermostat is open.
• Reset manual switch located above heater on humidifier cover.
• Verify contactor and transformer electrical plugs are fully engaged.
Non-resettable over-
temperature thermostats (in
power lines to heaters) are
open. (Model 1160 only.)
• Replace non-resettable thermostats.
• Check all components for over-temperature damage.
• Determine cause of dry fire by checking for a frozen contactor or a probe assembly malfunction
and remedy before restarting humidifier.
Reduced or no output
(even though water
level is correct)
Malfunctioning control
system
• Check 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.
• Check if the heater over-temperature thermostat has tripped. Reset if necessary.
• Check if the non-resettable over-temperature thermostats have tripped. Replace if necessary.
• Check fuse in power circuit. If open, replace fuse with equal fuse.
Heater malfunctioning • Verify that contactor and transformer electrical plugs are fully engaged.
• Verify that proper voltage is being applied to heaters.
• Check heater amperage.
• If heater power device is not functioning, replace.
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