Troubleshooting Guide - Aprilaire 800 Installation & Maintenance Instructions Manual

TRoUbleSHooTInG GUIDe

If a problem arises with the Aprilaire Model 800 Steam Humidifier, please review the following troubleshooting guide for possible causes and
solutions . If the problem persists, call Aprilaire Tech Support toll-free at 1-800-334-6011 . Please be prepared to describe the exact nature of
the problem .
Table 5 – Troubleshooting Guide
Problem Possible cause
Humidifier does No power to humidifier
not energize; steam
canister does not
heat up, display
lights not on
No power to low voltage
control circuit
Control terminals
are open
ADHC faults:
• Open, shorted,
or incorrect wiring
of control
Steam canister failure Improper wiring
Mineral buildup
on steam canister
electrodes
Steam canister electrode
corrosion
Unit does not fill No water supply to
with water fill valve
Unit control is not on
Malfunctioning fill valve
Drain valve is open
Fill valve does Malfunctioning level
not close control system
Fill valve is stuck
Drain valve is open
14
action
• Check main power supply.
• Check main line safety switch.
• Verify terminal block electrical connections.
• Verify humidifier is turned on.
• Check for proper supply voltage.
• Verify terminal block electrical connections.
• Check for control circuit voltage, 24 VAC.
• Check if auxiliary limit controls are not allowing system to operate, e.g., high limit
humidistat, airflow proving switch, etc . Reset, replace, or calibrate as needed .
• Check terminals for 24 VAC.
• Check control circuit wiring.
• Verify proper electrical connections.
• Inspect steam canister for severe mineral buildup on or around electrodes. If severe
mineral buildup is present, replace steam canister .
• Inspect electrodes for surface corrosion or pitting. This is usually caused by a high
chloride level in the supply water . Replace steam canister .
• Verify that manual water supply valve is open and that pressure exists.
• Check if in-line strainer in inlet port of fill valve is plugged. Clean strainer or replace.
• Press On/Off switch.
• If fill valve does not open:
– Check for obstruction in valve .
– Verify fill valve electrical connections .
– Verify proper 24 VAC to fill valve . If voltage is present and valve does not open,
replace valve .
• Check for obstruction in drain valve.
• Check that high water sensor electrical plug is fully engaged.
• Check if there is an obstruction that does not allow valve to seat properly. Clean or
replace valve as needed .
• Clean or replace drain valve if an obstruction in the valve does not allow complete
closure .