Honeywell RTH6400D1018 5–1-1-day Thermostat programmable *Open Box*
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Honeywell RTH6400D1018 5–1-1-day Thermostat programmable *Open Box*

Programmable 5-1-1 day with 4 program periods per day. For heating and air conditioning systems. Large backlit display with menu driven programming. Soft-key controls. Shows room and set temperature. Exclusive Smart Response technology. Compatible with most electric, gas oil single stage furnaces, heat pumps without backup heat, heat only, and cool only furnaces. Will not work on electric baseboard heat. Precise temperature control +/- 1 F. Automatically switches from heat to cool to adjust the preheating/cooling of your home so you can feel comfortable at your programmed times. Battery powered. Approximate size: 3.75-Inch H. x 6-Inch W. x 1.25 W. Off-white. ENERGY STAR rated.

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Maximize comfort, reduce household energy use, and save money with the RTH6400D 5-1-1 Programmable Thermostat from Honeywell. Featuring a user-friendly design that lets you program weekdays, Saturdays, and Sundays separately, this thermostat makes it easy to sync your home's heating and cooling system with your schedule.

The RTH6400D 5-1-1 Programmable Thermostat offers:
  • Separate programming for weekdays, Saturdays, and Sundays
  • Effective energy expense savings
  • Backlit display and easy push-button design
  • Intuitive adjustment for precise comfort control
  • Compatibility with a range of heating and cooling systems


Convenient and Efficient for At-Home Comfort
You know that turning down your heat at night saves you money, but you hate waking up and making breakfast in a freezing cold kitchen. Or you don't want to run your AC all day while you're at work, but you want your home to be cool and comfortable when you get home. That's where a programmable thermostat makes all the difference.


The customized settings add luxury to your home while affording you valuable savings on your energy bill. View larger.

Every day is unique. With this thermsostat, enjoy the freedom of pre-programming to fit your different daily needs. View larger.

Offering you the ability to program weekdays together and Saturdays and Sundays independently and allowing you to customize temperatures for four periods per day, this thermostat makes it simple to heat or cool your home for optimum comfort.

An Easy Way to Save Energy and Money
If programmed as directed, this thermostat also offers you the ability to save up to 33-percent on annual heating and cooling costs (savings may depend on the geographic region you live in and your energy usage). When it does come time to change the thermostat's battery, an easy-access compartment makes battery replacement fast and painless.

Exclusive Technology for Reliability and Ease of Use
Programming and monitoring the thermostat is simple with a soft-touch button interface and an easy-to-read display that shows the current room temperature and the set temperature simultaneously. This display is backlit, making it easy to see even in dimly lit rooms and hallways. All readouts are rendered in natural language instead of confusing symbols, and you can select whether you would like temperature readouts to appear in Fahrenheit or Celsius.

The thermostat features Honeywell Smart Response Technology and a feature that enables Auto Changes from Heating to Cooling, which continually adjusting the pre-heating or cooling of your home for effective results and precise comfort control within one-degree F of your desired temperature. The thermostat offers temporary and permanent hold settings for greater convenience.

Broad Compatibility for Use with Your Existing System
This thermostat is compatible with a broad range of 24-volt heating and air conditioning systems, including single-stage heating and cooling, heat pump systems without auxiliary (back-up) heat, gas fireplaces, and heating only or cooling only systems. It is not compatible with multi-stage heating and cooling, heat pump systems with auxiliary (back-up) heat, and electric baseboard heat (120-240 volts).

About Honeywell
With over 120 years of trusted reliability, Honeywell International is a diversified technology and manufacturing leader, serving customers worldwide with aerospace products and services; control technologies for buildings, homes and industry; automotive products; turbochargers; and specialty materials.

Whether you're flying on a plane, driving a car, heating or cooling a home, furnishing an apartment, taking medication or playing a sport, Honeywell products touch most peoples' lives everyday. Honeywell technologies are found in more than 150 million homes, 10 million buildings and a multitude of manufacturing plants around the world.

What's in the Box
RTH6400D 5-1-1 Programmable Thermostat, wire labels, wall anchors, mounting hardware, and an installation and user guide


With personalized temperature control, your household enjoys comfort day and night.

FrFrom the Manufacturer

A Honeywell programmable thermostat can save you up to 33 percent off your energy bill. You set it up to adjust the temperature when you are away or asleep---times when you don’t necessarily need to heat or cool your home to optimum comfort---and your heating and cooling equipment runs less. The RTH6400D with exclusive Honeywell Smart Response Technology continually adjusts the pre-heating/cooling of your home so you are comfortable at your programmed times. It also automatically determines if your home needs heating or cooling to provide maximum comfort. Simplified programming with easy to follow text instead of symbols. 

Data sheet

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