Brand: Aprilaire
Category: Humidifier
Document Type:
Language: EN
Manual for 800 - Troubleshooting and error codes + PDF Download
Uploaded: April 8, 2025, 1:57 p.m.
Manual Publish Date: 2010-06-01
Warranty Summary
Warranty information is not provided in this manual.
The Aprilaire Model 800 Canister Steam Humidifier generates steam by energizing electrodes in a water canister. Water is introduced through a fill valve and maintained at a specific level. Steam is then delivered through a dispersion tube into the HVAC system ductwork. The system includes safety features and is controlled by an Automatic Digital Humidifier Control (ADHC) to maintain desired humidity levels.
Troubleshooting and error codes
| Problem | Possible cause | Action |
|---|---|---|
| Humidifier does not energize; steam canister does not heat up, display lights not on | No power to humidifier |
• Check main power supply. Check main line safety switch. • Verify terminal block electrical connections. • Verify humidifier is turned on. |
| No power to low voltage control circuit |
• Check for proper supply voltage. • Verify terminal block electrical connections. • Check for control circuit voltage, 24 VAC. |
|
| Control terminals are open | • 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. | |
| ADHC faults: • Open, shorted, or incorrect wiring of control |
• Check terminals for 24 VAC. • Check control circuit wiring. |
|
| Steam canister failure | Improper wiring | • Verify proper electrical connections. |
| Mineral buildup on steam canister electrodes | • Inspect steam canister for severe mineral buildup on or around electrodes. If severe mineral buildup is present, replace steam canister. | |
| Steam canister electrode corrosion | • Inspect electrodes for surface corrosion or pitting. This is usually caused by a high chloride level in the supply water. Replace steam canister. | |
| Unit does not fill with water | No water supply to fill valve |
• 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. |
| Unit control is not on | • Press On/Off switch. | |
| Malfunctioning fill valve |
• 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. |
|
| Fill valve does not close | Drain valve is open | • Check for obstruction in drain valve. |
| Malfunctioning level control system | • Check that high water sensor electrical plug is fully engaged. | |
| Fill valve is stuck | • Check if there is an obstruction that does not allow valve to seat properly. Clean or replace valve as needed. | |
| Drain valve is open | • Clean or replace drain valve if an obstruction in the valve does not allow complete closure. |