A compact whole-house bypass evaporative humidifier engineered for small-to-medium residential layouts and tight mechanical spaces. The AprilAire Model 500 delivers up to 12 gallons per day (GPD) of humidification for tight homes up to 3,600 sq. ft. Built with a compact 9-1/2 in. square plenum cutout, the Model 500 easily mounts onto forced-air furnace supply or return ductwork where larger humidifiers cannot fit. Equipped with the Model 60 Automatic Digital Humidifier Control and outdoor temperature sensor, the system continuously adjusts moisture levels based on exterior Ontario winter temperatures to prevent condensation on exterior windows while maintaining comfortable indoor humidity.
Technical specifications
| Warranty | 5 year warranty Source: AprilAire warrantyWarranty is provided by the manufacturer under its own terms. See the source link for full details. |
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Key features
- Compact mechanical footprint — engineered with a 9-1/2 in. square plenum opening, ideal for tight furnace mechanical rooms and horizontal or vertical duct runs.
- Automatic digital humidity control — includes Model 60 digital controller and outdoor temperature sensor to prevent window condensation during severe winter freezes.
- Proven Model 10 Water Panel technology — heavy-duty expanded aluminum core with porous ceramic coating ensures uniform water distribution and evaporative output.
- Reversible bypass duct collar — 6-inch round bypass duct collar attaches to either side of the chassis for flexible right-to-left or left-to-right airflow configurations.
- Comprehensive hardware kit — includes 24 VAC Class 2 transformer, saddle valve, outdoor temperature sensor, and digital control module.
Sizing guide
| Tight construction (modern building code, 0.5 ACH) | Up to 3,600 sq. ft. (334 m²) |
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| Average construction (typical residential, 1.0 ACH) | Up to 1,800 sq. ft. (167 m²) |
| Loose construction (older heritage structure, 1.5 ACH) | Up to 1,200 sq. ft. (111 m²) |
Specifications
| Manufacturer | AprilAire |
|---|---|
| Series | 500 Series Evaporative Bypass |
| Model / SKU | 500 |
| Equipment type | Whole-house compact bypass evaporative humidifier |
| Evaporative capacity | 12 Gallons Per Day (GPD) @ 120°F plenum temperature |
| Coverage (tight construction) | Up to 3,600 sq. ft. (334 m²) |
| Coverage (average construction) | Up to 1,800 sq. ft. (167 m²) |
| Coverage (loose construction) | Up to 1,200 sq. ft. (111 m²) |
| Humidifier control included | Model 60 Automatic Digital Humidifier Control |
| Outdoor temperature sensor | Included (digital proportional reset) |
| Replacement water panel | Model 10 Water Panel |
| Bypass duct connection | 6 in. round duct collar (reversible left or right) |
| Plenum opening dimensions | 9-1/2 in. W × 9-1/2 in. H (241 × 241 mm) |
| Unit dimensions | 15-5/8 in. W × 13 in. H × 10-1/4 in. D |
| Electrical rating | 24 VAC, 60 Hz, 0.5 A |
| Transformer included | 120 VAC to 24 VAC, 10 VA Class 2 Transformer |
| Water feed rate | 3 Gallons Per Hour (GPH) |
| Water supply connection | 1/4 in. O.D. copper tubing with compression fitting |
| Drain hose connection | 1/2 in. I.D. flexible tubing to floor drain or pump |
| Water supply temperature | Cold or service hot water |
| Certifications | UL rated, AHRI Guideline F compliant |
Before you buy
- Requires an existing or field-cut 9-1/2 in. by 9-1/2 in. opening on the warm air supply plenum or cold air return duct with 6-inch round bypass ducting.
- The Model 60 Automatic Digital Control must be mounted on the cold air return duct at least 6 inches upstream of the bypass connection for accurate humidity sampling.
- Install the outdoor temperature sensor on an exterior wall facing north or east out of direct sunlight using standard low-voltage 18/2 wire.
- A continuous downward pitch must be maintained on the 1/2-inch drain hose to ensure gravity drainage to a floor drain or condensate removal pump.
- Annual replacement of the Model 10 Water Panel is recommended at the start of every heating season to maintain rated 12 GPD output.
Questions about ductwork fitment or humidifier controls? Contact our technical team for assistance.
Frequently asked questions
Which evaporative water panel does the Model 500 use?
The Model 500 uses the genuine AprilAire Model 10 water panel, measuring approximately 9.5 inches wide by 9.75 inches high by 1.75 inches thick.
What are the physical dimensions of the Model 500 cabinet?
The compact cabinet measures 15.6 inches wide by 13 inches high by 10.25 inches deep, fitting narrower duct drops where larger humidifiers cannot fit.
Does the Model 500 include an automatic digital humidistat?
Yes. The Model 500 includes the Model 60 digital automatic control with an outdoor temperature sensor to prevent window condensation during Canadian cold snaps.
What bypass duct size connects to the humidifier?
A 6-inch round galvanized sheet metal or flexible duct connects the humidifier collar to the opposite HVAC plenum with an integrated damper switch.
What electrical service is required for the solenoid?
The 24 V AC solenoid valve is powered by an included 120 V to 24 V 10 VA transformer wired to the furnace control terminal board.
What water line connection is used?
Connect a 1/4-inch O.D. copper or braided supply tube to the domestic cold or hot water supply pipe with the included saddle/shutoff valve.
What drain plumbing is needed?
Route a 1/2-inch I.D. flexible drain hose from the bottom drain fitting with continuous downward pitch to a floor drain or condensate pump.
When should the damper be switched to the Summer position?
Switch the integrated damper to the Summer (closed) position when the heating season ends and air conditioning starts, preventing conditioned air from bypassing the cooling coil.
How often should the water panel be replaced?
Replace the Model 10 water panel once per year in early autumn prior to turning on the furnace for the winter heating season.
Documents
- AprilAire 500 Series Whole-House Evaporative Humidifier Specification Sheet (PDF)
- AprilAire Canada All Products Specification Reference Guide (PDF)
- AprilAire Model 500 Humidifier Owner's Manual (PDF)
Specifications compiled from official AprilAire 500 Series Whole-House Evaporative Humidifier Specification Sheet (Lit. No. 381) and 500 Series Owner's Manual (B2209190). All specifications subject to manufacturer verification. View AprilAire 500 specifications (PDF).
Installation & Safety Notice: Whole-home bypass humidifiers require cutting into furnace supply/return plenum and connecting to a water supply. Installation by a qualified HVAC technician is recommended to prevent duct air leakage.
Common questions
Is installation included?
No. AVL Shop sells equipment only. Installation is done by an independent licensed contractor that you hire.
How is freight charged?
Freight cost is included in your written quote before you pay.
What warranty does this product have?
The manufacturer warranty applies. Where we have the manufacturer’s exact wording, it is shown in the Warranty row of the specifications on this page, with a link to the source.
How do I get a quote?
Use Request a quote on this page and send the model and your city or postal code.