Frequently Asked Questions

General Thermostat Questions

1. Where should my thermostat be located?
   
2. What is the Auto Mode and why would I use it?
   
3. When should I use emergency heat? (Heat pumps only)
   
4. Why does “- -“ appear when I press the outdoor button?
   
5. Why does the clock flash 12:00?
   

Aprilaire 8500 Series Questions

1. How do I change the temperature temporarily?
   
2. Why is the flame or snowflake flickering on the Aprilaire 8500 Series Thermostat?
   
3. Why does the display show AC?
   
4. How do I change the thermostat to read F? or C?
   
5. Between heating and cooling season, I want to turn my system off. Will this change the program?
   

Aprilaire 8300 Series Questions

1. How do I change the temperature temporarily?
   
2. How do I change the thermostat to read F? or C??
   
3. Why does Lo Bat show in the display of my thermostat?
   
4. Do I have to reprogram my thermostat after I charge the batteries?
   
5. On the 8300 Series Thermostats, should I have my fan set for “on” or “auto?”
   
6. What are the “PROG” and “MAN” arrow icons on the Aprilaire® 8300 Series Thermostat for?
   
7. Between heating and cooling season, I want to turn my system off. Will this change the program?
   

General Thermostat Questions

1. Where should my thermostat be located?
To assure accurate temperature control, the thermostat should be mounted on an inside wall in a frequently occupied space that best represents the building’s temperature. The thermostat should be mounted at least 18” from any outside wall and approximately 5’ above the floor. DO NOT place the thermostat:

• 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

2. What is the Auto Mode and why would I use it?
The Auto Mode will allow the thermostat to cycle heating or cooling equipment as the building temperature moves outside the comfort zone that you have entered as heat and cool set points in your thermostat. Use this position for optimum comfort and control.

3. When should I use emergency heat? (Heat pumps only)
Emergency heat should be used when there is a problem with your heat pump compressor or when the heat pump is not maintaining your comfort level.

4. Why does “- -“ appear when I press the outdoor button?
There is no outdoor temperature sensor attached to the thermostat.

5. Why does the clock flash 12:00?
The thermostat has lost power and the clock needs to be reset.

Aprilaire 8500 Series Questions

1. How do I change the temperature temporarily?
On the Aprilaire 8500 Series Thermostats, adjust up or down buttons to the desired temperature. The thermostat will maintain that set point for three hours. For indefinite override, press “hold” and adjust the thermostat to the desired temperature. The thermostat will maintain that set point until the resume button is pressed.

2. Why is the flame or snowflake flickering on the Aprilaire 8500 Series Thermostat?
The flickering flame or snowflake indicates that the thermostat is actively making a call for heat (flame) or air cooling (snowflake).

3. Why does the display show AC?
The thermostat has lost power from the heating or air conditioning equipment. This may occur during a power outage or during service to your HVAC Equipment.

4. How do I change the thermostat to read F? or C?
On an Aprilaire 8500 Series Thermostat, press the “Ÿ” and “/” buttons simultaneously.

5. Between heating and cooling season, I want to turn my system off. Will this change the program?
If you want to turn your system off, press the mode button on your 8500 Series Thermostat until “OFF” appears.

Aprilaire 8300 Series Questions

1. How do I change the temperature temporarily?
On the Aprilaire 8300 Series Thermostats, press the prog/man button so that the arrow icon is next to man. The thermostat will hold the set point until the prog/man button is pressed again.

2. How do I change the thermostat to read F? or C??
On Aprilaire Models 8334 and 8336 thermostats, remove the cover and move the switch marked C-F to the desired setting and press the reset button. On Aprilaire Models 8353 and 8355, press and hold “set”, press “/” and then release both simultaneously.

3. Why does Lo Bat show in the display of my thermostat?
The batteries will need to be replaced.

4. Do I have to reprogram my thermostat after I charge the batteries?
The Aprilaire Model 8300 Series will hold the program for 30 to 45 seconds while the batteries are being replaced.

5. On the 8300 Series Thermostats, should I have my fan set for “on” or “auto?”
In the “on” position, the fan will run continuously. 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 with heating or air conditioning calls.

6. What are the “PROG” and “MAN” arrow icons on the Aprilaire® 8300 Series Thermostat for?
When the arrow is displayed next to “PROG,” the thermostat will follow the times and temperatures programmed into the thermostat. When the arrow icon is on next to “MAN,” the thermostat will hold the set point shown on the display until the prog/man button is pressed.

7. Between heating and cooling season, I want to turn my system off. Will this change the program?
If you have an 8300 Series Thermostat, simply slide the selector switch to the off position. This will not affect the programming of the thermostat; however, the thermostat will have to be placed into the heat, cool, on auto mode to again operate the equipment.