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Aprilaire Model 8446 Thermostat

The Aprilaire Model 8446 Thermostat offers the benefits of bringing your heat pump HVAC system into the digital age, while being extremely easy-to-use. If you don’t need a programmable thermostat, but desire digital accuracy and the convenience of an electronic over a mechanical thermostat, then the Aprilaire Model 8446 Thermostat is the best choice for your home.

The Aprilaire Model 8446:

  • Works with heat pump systems
  • Provides pinpoint digital accuracy and control for ultimate comfort and outstanding energy efficiency
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Right Choice

The Aprilaire Model 8446 Thermostat offers basic functions in a quality digital control. It works with heat pump HVAC systems and is installed by a local HVAC professional.

Features and Benefits

The Aprilaire Model 8446 Thermostat is attractive, easy-to-use and offers:

  • A large 4.5 square-inch LCD Screen with a high-contrast, backlit display for easy reading.
  • Simultaneous display of room temperature, temperature setting and outdoor temperature, in Fahrenheit or Celsius.
  • Service reminders for your HVAC system, humidifier, dehumidifier and air filter. Protects your equipment and ensures the longevity of your investment.
  • Simple setup menu for activating optional features.
  • Quick-reference instructions on board
  • Soft-touch keys
  • 5-year warranty

Take Control of Your Family’s Comfort

With the Aprilaire Model 8446 Thermostat, you don’t just control temperature—you control your family’s comfort. Find a dealer near you to discuss your family’s specific needs today, or get replacement parts for your existing Aprilaire equipment here.



  • Where should my Aprilaire thermostat be installed?

    To ensure accurate temperature control, Aprilaire thermostats should be mounted on an inside wall in a frequently occupied space which best represents the home’s temperature. The Aprilaire thermostat should be mounted at least 18” from any outside wall and approximately 5’ above the floor and may be mounted to a vertical junction box. Your Aprilaire thermostat should not be: behind doors, in corners or other dead air spaces; in direct sunlight or near lamps, appliances or other sources of heat; On an outside wall or a wall exposed to an unconditioned space (e.g., garage, etc.); In the flow path of a supply register, in stairways or near outside doors; On a wall where concealed pipes and/or ductwork will affect the thermostat; Near sources of electrical interference such as arcing relay contacts.

  • Will turning my HVAC system off between the heating and cooling seasons affect the programming of my Aprilaire programmable thermostat?

    Aprilaire programmable thermostats, models 8463, 8465, 8466, 8476, 8570, 8600, 8620 and 8910 include a mode function. One of the mode selections is off. The off mode simply does not allow the thermostat to make a call for heating or cooling. It has no affect on the programming of the thermostat. The Aprilaire thermostat will have to be placed into the heat, cool, on auto mode in order for the Aprilaire thermostat to operate the heating and cooling system.

  • What is the difference between fan on or auto on my Aprilaire thermostat?

    Aprilaire thermostats have the option for fan on or auto. In the “on” position, the heating and cooling system fan will run continuously 24/7. Continuous fan operation is desirable to provide maximum comfort in the home by eliminating hot or cold spots caused by poor airflow. Continuous fan operation also is the most effective way to use a whole-house air cleaner such as an Aprilaire® High Efficiency Air Cleaner. In the “auto” mode, the fan will run only when the heating and cooling system is making a heating or cooling call.

  • When should I use the emergency heat mode on my Aprilaire thermostat?

    Aprilaire manufactures thermostats (models 8446, 8448, 8465, 8466, 8476, 8570, 8600, 8620 and 8910) which interface with heat pumps. Heat pumps include a secondary source of heat (typically a gas furnace or electric strip heat). This is activated by the Aprilaire thermostat when the heat pump isn’t capable of raising the indoor temperature to the desired set point and is referred to as staging. Anytime there is a desire to skip the staging process of the thermostat to raise the indoor temperature, the Emergency Heat mode can be manually activated. This is done by changing the mode on your Aprilaire thermostat from Heat to Emergency Heat. The Emergency Heat mode skips the operation of the heat pump and only operates the secondary source of heat.

  • What is the “Auto Mode” on the Aprilaire thermostat and why would I use it?

    The Auto Mode allows the Aprilaire thermostat to call for heating or cooling based on the heating and cooling temperature set points. As the temperature in the living space changes the thermostat will look at the heating and cooling set points to determine whether a call for heating or cooling is required. Whenever the living space temperature is different than the desired temperature, the Aprilaire thermostat will make a heat or cool call, depending on what is necessary to bring the living space temperature back to the desired temperature. This is different than what occurs when the Aprilaire thermostat is in the heat mode or cool mode. In the heat or cool mode the Aprilaire thermostat can only make a call for heating or cooling but not both. The mode must be in the heat mode to make a heat call and in the cool mode to make a cool call. In Auto it can make either call.

  • Does my Aprilaire model 8400 Series Thermostat need to be re-programmed after changing the batteries?

    The Aprilaire model 8400 series thermostats will hold the program for 30 to 45 seconds while the batteries are being replaced. It is best to have the new batteries with you when removing the old batteries, otherwise if more than 45 seconds pass the thermostat will need to be re-programmed.

  • What is the Aprilaire model 8910 home comfort control system?

    The Aprilaire model 8910 home comfort system is designed to control temperature as well as intuitively managing the indoor air comfort throughout your home. It does this by operating Aprilaire indoor air quality products (IAQ) such as a humidifier, dehumidifier, air cleaner and ventilation system all from one control. The Aprilaire model 8910 home comfort system consist of a thermostat which installs in your living space and an equipment control module which installs near the heating and cooling system. We ask for you to please contact your heating and cooling system installer to obtain an Aprilaire model 8910 home comfort control system or if you need the name of a local dealer, please use our Dealer locator: http://aprilaire.com/index.php?znfAction=FindDealer

  • Can the Aprilaire model 8910 home comfort system be wired to an Aprilaire zoned comfort control system?

    Yes, the Aprilaire model 8910 Home Comfort Control can be used with a zoned comfort control system. The Model 8910 is designed to operate other Aprilaire indoor air quality products (IAQ) from one control. When wired to an Aprilaire zoned comfort control system the 8910 interface should be wired to the primary zone (largest zone, master bedroom suite etc…) and only the primary zone will be able to call for the operation of the IAQ products. Any of the zones can be the primary zone. The thermostat from the 8910 operates the zone it is connected to the same way any thermostat would. The operation of the IAQ products by the 8910 interface is a separate function than a call for heating, cooling or fan operation.

  • What us the difference between the 8600 and the 8620 Aprilaire thermostats?

    The model 8600 and 8620 Aprilaire thermostats can control a two heat two cool conventional heat cool system or a 4 heat 2 cool heat pump system. Both thermostats can be configured as programmable or non-programmable and include service reminders (humidifier, air filter, dehumidifier and HVAC system). The model 8620 Aprilaire thermostat also includes an outdoor temperature sensor, offers event based air cleaning and includes a built-in relative humidity sensor. In addition to controlling temperature the model 8620 can control one of the following: humidification, dehumidification or ventilation.

  • How do I change my model 8600 series thermostat, 8620 or 8910 thermostat from Fahrenheit to Celsius?

    The temperature scale s adjustable between Fahrenheit and Celsius in the set up menu and is system setting option 04. The factory default is Fahrenheit. To access the set up menu preform the following:

  • How do I change my model 8400 series thermostat or 8476 thermostat from Fahrenheit to Celsius?

    The temperature scale is adjustable in the set up menu and is system setting option 01. The factory default is Fahrenheit (setting range set to 0. Celsius setting range is 1). To access the set up menu preform the following: