Aprilaire 1150 - Manual (Page 32)

TROUBLESHOOTING
Problem Possible Cause Action
All indicator lights are
blinking sequentially
from right to left
The humidifier is in a forced
cool-down period prior to
a required automatic drain
sequence.
• This is normal operation. DO NOT RESET POWER. The humidifier will automatically resume
making steam once it has cooled down, drained, and refilled.
All indicator
lights are off
On/Off switch is off • Push On/Off switch on display panel.
Display panel ribbon cable
connection
• Connect display panel ribbon cable.
• Verify ribbon cable is connected correctly. See Figures 29 and 30.
Transformer secondary
circuit breaker tripped
• Check for wiring shorts; reset breaker.
Power panel breakers are
open
• Check power block for proper voltage present at transformer.
• Verify transformer electrical plug is fully engaged.
Steam light on the
display panel is
blinking on and off
The enable/safety circuit is
not satisfied.
• If no other lights are on or blinking, check the airflow proving switch:
– Verify that tube orientation in the duct is correct.
– Verify tube is connected to the switch correctly.
– If connections are correct and switch does not close with airflow, replace switch.
• Check high humidity limit switch (if installed):
– Verify connection per the wiring diagram and the diagram on the high humidity limit switch cover.
– Verify that the high humidity limit switch is the correct distance downstream of distribution tube.
– If connections and location are correct, replace high humidity limit switch.
Low water condition • If the fill light is also on:
– Verify that the water shut-off valve is open.
– Check fill valve strainer; clean or replace if clogged.
• If the fill light is also blinking, refer to the “Fill light on the display panel is blinking on and off”
section below.
• Verify that lever on drain valve actuator is in ‘Auto’ position.
Fill light on the display
panel is blinking on
and off (fill fault)
Unit will not operate
When in a fill sequence, the
internal controller allows
15 minutes for water to
reach the maximum upper
water level. If water is not
sensed at the top probe of
the probe assembly after
filling for 15 minutes, the
fill light on the display
panel will blink on and off.
There are two causes for
this: either the chamber
did not fill, or the chamber
filled but water is not
being detected.
Chamber is not full
• Verify that lever on drain valve actuator is in ‘Auto’ position.
• Verify that water shut-off valve is open.
• Verify that the fill valve electrical plug is fully engaged.
• Verify proper fill valve wiring at terminals 33 and C.
• Verify voltage supplied to fill valve is correct. Valve coil should be 24 VAC.
• Check fill valve strainer; clean or replace if clogged. Check the strainer by disconnecting the fill
valve inlet fitting. Remove the strainer with a small screwdriver.
• Fill valve may be plumbed backward. Note flow direction and correct as needed.
• Verify that water supply pressure is at least 25 psi (175 kPa).
• Verify that fill and drain valve wiring are not reversed.
• Remove fill valve and check for any foreign material plugging the valve.
• Excessive water hammer can bend a needle valve on the supply line and make it difficult to open.
If this is happening, the valve may need to be replaced. Install a water hammer shock arrestor.
Chamber is full
• Clean or replace probe.
• Check water conductivity. Water conductivity must be at least 100 µS/cm 2 . Add salt to increase.
Drain light on the
display panel is
blinking on and off
(drain fault)
Unit will continue
to operate
When in autodrain sequence
or end-of-season drain, the
internal controller allows 14
minutes for the water level
to drop from the top probe
to below the lowest probe.
If the chamber does not
drain to this level in the time
allotted, the drain light on
the display panel will blink
on and off.
• Verify that drain valve electrical plug is fully engaged.
• Check drain valve wiring at terminals 32 and C.
• Check for voltage present at the valve. Input power to the drain valve actuator should be
24 VAC; if present, clean or replace valve.
• Check if the chamber drain outlet from the humidifier is plugged. Clean if needed.
Water detection probes • Clean probes or replace probe rod assembly.
Fill valve • Fill valve may be plumbed backwards. Note flow direction on valve body and replumb if necessary.
• If fill valve is plumbed correctly and leaking water, replace fill valve.
Drain line is backing up
with water
• Verify drain line pitch. Pitch drain pipe toward drain 1/8”/ft (1%) minimum.
• Verify drain line size. If piping run is over 10’ (3 m) , increase drain pipe size from ¾” (DN20) to
1¼” (DN32).
• Verify that the drain line is not plugged. Disconnect drain piping from the humidifier at the hose
or union connection. Replace or clean drain piping if there is standing water in the piping or if
water does not flow freely through the drain piping.
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