Programmable Thermostats

Reviews of digital programmable thermostats

Honeywell RTH8500D

buy a Honeywell RTH8500D

Click Here to find the Best Price on Amazon for the Honeywell RTH8500D

List of Specifications:

  • 7 Day programming and 4 periods per day
  • Large touchscreen with back light
  • Intuitive, menu driven touchscreen programming
  • Smart Response
  • Temporary override
  • Vacation mode
  • Auto change-over
  • Batteries not needed
  • Filter warning
  • Can cycle fan
  • Real time display that takes account for daylight saving
  • Keeps settings even after a power outage
  • Energy Star approved
  • 1 year warranty
  • Price $109 (use the link above to check the latest price on Amazon)


  • Central air, heating only, cooling only, single stage heat pumps, heat pumps with auxiliary, 2 wire hydronics, gas, 750 Millivolt, gas fireplaces
  • up to 2 stages of heating and 2 stages of cooling


The Honeywell RTH8500D 7 Day Touchscreen Programmable Thermostat is the eighth best selling thermostat on It is a device that has excellent compatibility and nearly every conceivable function a home owner could want from a programmable thermostat excepting wi-fi and humidity control. And at just over $100 this Honeywell International thermostat is being sold at a good price.

The Honeywell RTH8500D gives the user a program slot for each day of the week and for each day the user can set up for 4 periods of heating and cooling. Programming is via a large touchscreen with a backlight. The thermostat uses an intuitive menu driven style of programming that is easy to understand and lets the user quickly set up his or her programs.

The thermostat is compatible with nearly all 24 volt HVAC systems including heating only, cooling only, furnace (warm air), central air conditioning, heat pump (with and without auxiliary heat), hot water, steam or gravity, 750 Millivolt, and gas fireplaces. The thermostat can also manage up to 2 stages of heating and cooling. This makes the Honeywell RTH8500D far more compatible than the Lux Products TX9100E or Lux TX9000TS.

The Honeywell RTH8500D has temporary hold, vacation mode, auto change-over and smart response. Having a vacation mode makes the Honeywell RTH8500D better than the Honeywell RTH7500D and Honeywell RTH7600D which are both models missing vacation mode. This is a useful function because you can set the thermostat on a timer. Until the timer point is reached (when you return home) the thermostat keeps the HVAC just ticking over to protect your house.

The smart response function on the Honeywell RTH8500D is a powerful function that tracks how long it takes to heat or warm a room during the changing of the seasons and uses this information to pre-heat or pre-cool a room so at the start of a programmed period the temperature is just as you want it.

The Honeywell RTH8500D 7 Day Touchscreen Programmable Thermostat is accurate to 1 degree Fahrenheit and is a reliable device. It is an Energy Star approved device and comes with a 1 year warranty.

Other features include the ability to cycle the fan. The clock works in real time and automatically makes changes to compensate for daylight saving. The thermostat can be hardwired into the HVAC so it can be powered by the mains. This obviates the need for battery changes. The Honeywell RTH8500D can also keep programmed settings even after a power outage.


There is very little that you can write in criticism of the Honeywell RTH8500D. It has a whole slew of functions and can be installed onto most heating/cooling systems.

As with all Honeywell thermostats, the RTH8500D is missing a swing control function. Instead the Honeywell RTH8500D limits the number of cycles of the heating/cooling per hour. This is a system that usually works well to stop the HVAC systems from becoming damaged with too much short cycling. The system is particularly suited to temperate zones. For more extreme conditions it is not certain whether swing control is not a better option.

The only other notable function that is missing from the Honeywell RTH8500D is keyboard lockout. If this is important for you because your programmable thermostat will be placed in a public spot then you should look at a Lux Products thermostat.

Amazon Reviews

There are surprisingly few reviews of the Honeywell RTH8500D – only 12. Of these 12 reviews, 9 people give the thermostat 5 stars and the other 3 give the Honeywell RTH8500D 4 stars.

As you would imagine with mostly 5 star reviews, opinions are mostly positive about the device. One reviewer noted how useful the vacation mode is. Another that the pre-set times and temperatures (in line with Energy Star recommendations) were useful guidelines.

A reviewer from North Carolina noted that “set up was a cinch” and the temporary hold works effectively.

The only negative comments were about the touchscreen interface. One person found it ‘wonky’ and another that the backlight didn’t stay on for long enough

Keynote Quote:

“Highly recommended! I have three of these in my home, one for each zone.”

W. Price

Sat, January 22 2011 » Honeywell, Under $150

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