Aprilaire 500
Aprilaire ByPass FlowThru Humidifier with Digital Humidistat 12 gpd
  17 GPD 12 GPD 17 GPD 18 GPD

Aprilaire 500 flow-thru bypass whole-house humidifier. The Model 500 humidifier is designed for use in small to mid-size homes. If room permits we recommend using a larger humidifier, the 500 and 600 have the same water feed rate of 3 gph. The 600 would be more efficient with its larger water panel.

The Model 500 is a complete system and includes the humidifier with a built-in bypass damper, the water panel (#10), digital automatic humidistat (Model 60) with outdoor temperature sensor, self-piercing saddle valve, and 24vac transformer (#4010). Our photos (click View More Images above) for a view of all the items included. Items not included is 6" bypass duct, copper tubing, drain tubing, and thermostat wire.

Evaporative Capacity 0.5 gph
Unit Size 15-3/8"W x 13"H x 10¼"D
Plenum Opening 9½"W x 9½H
Electrical data 24 Vac, 60 Hz, 1/2A

Aprilaire 500 Measurement

Aprilaire 500 Humidifier Dimensions: 15-1/8 x 13 x 10-1/4 inchesThe Aprilaire 500 can be mounted on the return or supply duct. The air flow can run in either direction, in to the 6" bypass opening or out of the bypass opening.

The 500 can be configured with the 6" bypass duct connection on the right or left side.

Aprilaire Model 60 Digital Humidistat

Aprilaire 60 Humidistat New FeaturesThe Aprilaire 500 operates best when the furnace blower is turned on.

The Model 60 digital humidistat can turn on your HVAC blower when there's no need for humidification or heat. It works in conjuction with your heating, ventilating, ait cinditioning equipment (HVAC) to control the operation of the humidifier.

A new feature of the Model 60 is a simple onboard switch for manual mode or automatic mode. Automatic mode adjusts the humidity based on the outdoor tempreature. This feature can be disabled by a click of a switch. The previous Aprilaire humidistats required installing a manual mode resitor (see Model 60 Owners Manual).

What is a Flow-Thru Humidifier?

The term Flow-Thru refers to water trickling through the water panel and out a drain. The advantages of a flow-thru design is reduced maintenance and no standing water. Scale from calcium and lime gets flushed out of the water panel and down the drain. The water panel is an aluminum mesh with a porous pumice-like coating that inhibits growth of slime and is easy to change (once a year).

The disadvantage of the Flow-Thru is water usage. When in operation water flows in to the 700 water panel 6 gph. We are in the northeast where this is not an issue. We get a flat rate water bill unless there is excessive usage then the rate goes up. The Flow-Thru humidifier does not cause excessive usage.

The Flow-Thru is an evaporative humidifier and requires hot air. If not using hot air then hot water should be used. We see little humidity gain if our Flow-Thru humidifier is operating with cold air (and cold water). We run our blower on constant to best utilize our electronic air cleaner, but our humidifier is wired to only operate only when there is hot air and works very well.

Flow-thru Humidifier Type Demostration

By-Pass Versus Power Humidifier

By-pass Flow-Through Humidifier Demostration
Power Flow-Through Humidifier Demostration

The term By-Pass or Power refers to the driving force behind the air flow. The Power humidifier (aka Fan Power) uses a fan to draw the air thru the humidifier. The ByPass humidifier uses a 6" diameter duct that connects the supply to the return duct.

In the ByPass configuration the air leaving the furnace is routed back to the supply. The warm air leaving the furnace takes this short-cut of least resistance and bypasses the long trip down the duct work, in to the house, and back through the return. The ByPass is the 6" round duct work shown below. During the the hot humid A/C season the ByPass duct should be closed with the butterfly valve since the air flow through the humidifier would not be needed.

The Power humidifier uses a fan to draw air in from the duct and through the humidifier and exhausts back out in to the duct. The air is drawn in through duct at the center of the humidifier and back out in to the duct at the sides. The power humidifier should be mounted in vertical warm air flow.

The Model 400500, and 600 are ByPass humidifiers. The 700 is fan powered.

Manual Versus Automatic Humidistat

The indoor humidity level needs to be set based on the outside temperature. This is to prevent water from running down the windows. The cool air near the windows can not hold the humidity and water will condense on the glass. To prevent this condensation, the indoor humidity level is sacrificed by lowering the humidistat.

An automatic humidistat (Aprilaire 60) adjusts the humidity by using an outside temperature sensor.

The Aprilaire manual humidistat as used in earlier Aprilaire humidifiers (Model 4655) requires adjusting the relative humidity based on the outside temperature. A manual humidistat needs to be set back as the season gets colder. The chart below shows the humidity setting for a range of outside temperatures.

When The Outdoor
Temperature is
This Relative Humidity
Should Be Maintained

The New Aprilaire 500 Replaces 500A

In 2009 Aprilaire consolidated the Models 500M and 500A to the Model 500. The new Model 500 is identical to the earlier 500A, except the new 500 does not include a 2nd (#10) Water Panel and a DVD Video.

The difference between the 500A (automatic) and 500M (manual) was the 500M included a low cost manual humidistat (#4655) instead of the Automatic Digital humidistat (#58) that was included with the 500A.

The new 500 now includes the humidistat (Model #60) that can be operated as a Manual or Automatic humidistat.

Previous to the 500A & 500M was the Model 500 Series One. This early Model 500 was Cream in color whereas since the 500A & 500M (2008) the color has been a light Slate.

Related Products

Aprilaire 10 Water Panel
Aprilaire Water Panel Pad Size 9½x9¾x1½
Price: $13.00
HE225H8908 ByPass FlowThru Humidifier
Honeywell ByPass FlowThru Humidifier w/H8908 12 gpd
Price: $148.00
HFT2100 ByPass Flow-Thru Humidifier
White-Rodgers ByPass Flow-Thru Humidifier 14 gpd
Price: $152.00
Aprilaire 600 ByPass Flow-Thru Humidifier
Aprilaire 600 Humidifer with Digital Humidistat
Price: $204.00
Aprilaire 400 configured with the duct on the right side
Aprilaire 400 Humidifer with Digital Humidistat
Price: $227.00
Aprilaire 700 Power Flow-Thru Humidifier
Aprilaire 700 Humidifer with Digital Humidistat
Price: $311.00
Shopping Cart
Your cart is empty.
Browse Categories
1 BBB Customer Reviews