AprilAire S86NMU / S86NMUPR Multi-Stage Universal Thermostat — Owner's Manual

Full Owner's Manual for the AprilAire S86N MU Multi-Stage Universal Thermostat and S86N MUPR Multi-Stage Universal Thermostat with IAQ (Indoor Air Quality) control — covering the home screen, mode/fan selection, program schedules, indoor air quality functions (S86N MUPR only), maintenance reminders, and the 5-year limited warranty.

Thermostat Features

• Displays room temperature, room humidity, temperature setting, and outdoor temperature.
• Air filter, humidifier, dehumidifier, and HVAC service reminders.
• Programmable fan control with fan circulation mode.
• Easy-to-use temperature control that can override the program schedule at any time.
• Progressive recovery ensures proper temperature at the start of a program event.
• Sensor averaging with the ability to assign a sensor to a schedule event.
• Indoor air quality control (S86N MUPR only) — only one of humidifier, dehumidifier, or ventilation accessory can be controlled per installation.
• Heat Blast® raises room temperature 3°F to 5°F on demand.
• Easy-to-read color display; 7-day programmability.

Home Screen & Main Menu

The Home screen shows Equipment Status, Room Temperature, Room Temperature Setting, and Hold status, with Up/Down arrows to adjust temperature, a Back button, and a Select button that opens the Main Menu. The Main Menu includes: Mode, Fan, Hold, Schedule, Heat Blast, Humidifier, Dehumidifier, Ventilation, Air Cleaning, Vacation, and Settings (availability depends on installed options and model).

Screen Saver: starts 45 seconds after inactivity; press any button to wake the screen. The screen saver view shows current time, room temperature, indoor RH% (except S86N MU), and outdoor temperature.

Operation

Select System Mode

1. Press SELECT to enter the Main Menu.
2. Scroll to Mode and press SELECT.
3. Choose: Heat (heating only), Cool (cooling only), Auto (automatically switches between heat/cool if enabled in installer setup), Emergency Heat (heat pumps with auxiliary heat only — the heat pump itself will not run in Em Heat mode), or Off.
4. Press SELECT to save, or BACK to exit without saving.

Change Temperature Setting

From the Home screen, press the up/down arrows to adjust the current setting. The new setting takes effect 3 seconds after the last adjustment, or press SELECT to save immediately and return to the Home screen.

Select Fan Setting

• On: fan runs continuously — maximum air circulation/filtering.
• Auto: fan runs only when heating or cooling is active.
• Circulate: same as Auto, but guarantees the fan runs at least 30 minutes per hour — balances energy savings with air circulation/cleaning.

When fan mode is changed during a program event, it remains in that mode until the next scheduled event starts. To run continuously through all events, program Fan On directly in the schedule.

Maintenance Reminders & Lockout

Maintenance reminders are configured by the installer to flag when equipment is due for service — call your HVAC dealer, then reset via the Reset option on the reminder message or the Reset Service Reminders option in Settings.

Users can lock out thermostat controls (see User System Settings Table). To temporarily override lockout, press and hold SELECT for 7 seconds.

Indoor Air Quality Functions (S86N MUPR)

Event-Based™ Air Cleaning

Select Air Cleaning from the Main Menu. Offers two temporary events and three persistent modes; the fan activates for air cleaning purposes.

• 3 Hrs (event): air cleaner runs 3 hours continuously, then returns to the most recent mode (Auto/Continuous/Off) — useful after vacuuming.
• 24 Hrs (event): runs 24 hours continuously for seasonal allergy spikes, then returns to the prior mode.
• Auto (mode): runs a minimum of 30 minutes/hour, tracking heating/cooling runtime; turns on automatically if the 30-minute minimum isn't reached — maximizes air cleaning while minimizing energy use.
• Continuous (mode): maximum air cleaning — active 24/7.
• Off (mode): fan doesn't run solely for air cleaning (still occurs during normal heating/cooling fan operation).

Humidifier Control (S86N MUPR only, if installed)

Configured by the installer for either Automatic or Manual mode.

Automatic Mode: the thermostat adjusts relative humidity based on outdoor temperature to provide as much humidity as possible while avoiding window condensation. Start with the humidity setting at level 3 (low-normal); over the next 24–48 hours, adjust for more or less humidity based on comfort and the home's construction. Minor adjustments may still be needed during the coldest days of the first heating season; after that, it shouldn't need further adjustment.

Manual Mode: requires anticipating outdoor temperature drops/rises and adjusting manually to maintain humidity while avoiding condensation.

Dehumidifier Control (S86N MUPR only, if installed)

Configurable to control dehumidification via a whole-home dehumidifier or the air conditioner. Set the desired % relative humidity and turn dehumidification on/off. Start with a 60% setpoint when first installed; let it run to that setpoint before adjusting further — raise the setting if the air feels too dry (reduces runtime), lower it if it feels too damp/moldy (increases runtime). It's common for dehumidification to run long periods when first installed, since your home's materials must first release absorbed moisture.

If dehumidification is done with the air conditioner: the thermostat will overcool up to 3°F beyond the cooling setpoint for dehumidification purposes (may not always be sufficient to meet the setpoint).

Energy tips: turn the dehumidifier control OFF when windows are open (just like with A/C). For extended summer absences, set relative humidity to 60% and cooling to the highest comfortable/safe level, or use the Vacation hold to adjust both dehumidification and cooling setpoints at once.

Fresh Air Ventilation (S86N MUPR only, if installed)

Runs on a predetermined hourly schedule set by the installer; can be temporarily overridden.

• 3 Hours (event): ventilation runs constantly for 3 hours, then returns to Auto/Off — e.g., to dilute cooking odors.
• 24 Hours (event): ventilation runs constantly for 24 hours, then returns to Auto/Off — e.g., on a day with good outdoor air quality.
• Auto (mode): cycles per installer-set parameters to meet ventilation requirements.
• Off (mode): ventilation does not run.

Program Schedule & Holds

Understanding Program Schedules

Each daily schedule has four sections: Wake (temperature at wake time), Leave (temperature while away), Return (temperature for arriving home), and Sleep (nighttime temperature).

These defaults can be changed to fit your schedule; AprilAire recommends them because they reduce heating/cooling expenses. Fan is preset to Auto for all events.

Progressive Recovery

Pre-heats or pre-cools before a scheduled event so the desired temperature is reached exactly at the start of the event. Example: with a 6:00 AM Wake event at 70°F heat and a 62°F Sleep setpoint, heating begins before 6:00 AM so 70°F is reached right on schedule.

How to Modify Program Schedules

1. From the Schedule option, turn the schedule On/Off, or select Modify to change default settings for a specific day or group of days (All Days, Weekdays, Weekends, or individual days).
2. Adjust Wake details (Start time, Heat, Cool, Fan) and select Next to proceed through Leave, Return, and Sleep in sequence.
3. After modifying a group of days, Save & Exit. After modifying a single day, you can copy those settings to other days/groups, confirm the copy, then Save and Exit or Edit More Days.

On/Off: when the schedule is turned Off, the thermostat holds the current temperature setting until manually adjusted.

Heat Blast® (if installed)

Raises the current room temperature 3°F to 5°F (per installer setup), then resumes normal operation. Select Heat Blast from the Menu and toggle ON to activate, OFF to cancel. Only available if enabled in Installer Setup and the thermostat is in Heat or Emergency Heat mode.

Program Schedule Holds

Temporary Hold: press the up/down arrows to immediately adjust temperature while a schedule is running — holds until the next scheduled event. Can also be set/canceled/adjusted via the Hold option in the Menu (including the hold's end time).

Vacation: suspends the programmed schedule for an extended period, maintaining a selected temperature (and optional dehumidification setpoint) until the vacation end date/time, then automatically resumes the normal schedule. Turn off the Vacation hold manually from the Vacation menu option if you return early.

Setup Menu — User System Settings

Limited Warranty

The AprilAire Thermostat is warranted for 5 years from the date of installation against defects in materials or workmanship. Research Products Corporation's exclusive obligation is to supply a free replacement for any thermostat found defective within that period, returned (with proof of installation date) no later than 30 days after the 5-year period, to the original supplier or to Research Products Corporation, Madison, Wisconsin 53701.

This warranty does not cover labor costs or defects in workmanship/materials furnished by the installer (as opposed to the thermostat itself). It is void if the thermostat was not installed by a qualified heating and air conditioning contractor. Implied warranties of merchantability/fitness are limited to the 5-year period; incidental/consequential damages (other than personal injury) are excluded. Some states don't allow such limitations, so they may not apply to you. Register your product at aprilaire.com, or mail registration info to Research Products Corporation, P.O. Box 1467, Madison, WI 53701.