Aprilaire Model 8551 Owner's Manual

About this manual

The Aprilaire Model 8551 is a 5-2 day programmable electronic thermostat designed to control heating and cooling equipment. It allows users to set up to four time schedules per day for weekdays (Monday through Friday) and one program for weekends (Saturday and Sunday). The device features buttons for programming event times, setting desired temperatures, and managing fan operation.

What's inside

• Setting Or Changing The Clock
• Setting Or Changing The Weekday Program
• Setting Or Changing The Weekend Program
• Reviewing Programmed Time Schedules And Temperature Settings
• Thermostat Operation
• Temperature Control
• Equipment Control
• Cleaning

Specifications

Frequently asked questions

How do I set the clock on the thermostat?

Press the CLOCK button to select the day, then press it again to set hours and minutes using the DECREASE or INCREASE buttons.

How do I start running the programmed schedule?

After programming all temperatures and times, press and release the RESUME button to start running programs.

Can I hold a new temperature indefinitely?

Yes, pressing and holding the DECREASE or INCREASE buttons changes the set-point, which can be maintained indefinitely by pressing and releasing the HOLD button.