Purchasing a new thermostat for the HVAC system in your home is not something you have to do frequently. When you then, due to circumstances, have to purchase a new thermostat you might wonder how to choose the right one. You probably have many questions such as: Is it better to compare different thermostats in detail instead of just asking a few friends their opinion? Are there specific brands to look at? What are the aspects I have to compare?

Yes, you have to compare different thermostats to enable you to find the one that suits your circumstances the best. And you have to compare aspects like price, energy-saving capabilities, compatibility, and control via your smartphone.  Are there specific brands to look at? For years Ecobee and Honeywell thermostats have been trusted by clients and a comparison of their models is a good starting point.

Ecobee4 vs Ecobee3 Lite vs Ecobee SmartThermostat
Ecobee4 Thermostat

Ecobee 4 thermostat

Honeywell TH9320WF5003

In this article, we’ll first answer the question of why you have to compare different thermostats before buying. Then we will provide you with a table, list and chart to make a quick comparison between the two thermostats we are comparing – the Ecobee4 and the Honeywell RTH9585WF, and then we discuss some of the main differences and similarities you have to take a look at. Remember, although we only compare one model of each manufacturer you use the same principles and ask the same questions when you compare other models and brands. 

Why do I have to compare different thermostats before buying?

The top manufacturers of home thermostats are continuously in competition with each other to provide “the best” thermostat to clients. This competition amongst manufacturers is to the benefit of every homeowner who is looking for an effective and efficient thermostat because each brand tries to offer a thermostat that is more accurate and easier to use than the competitors’ devices. 

Every new model on the market has been developed to have more program possibilities and to be more of a smart device than any other on the market. 

However, although this “battle of the brands” ensures that thermostats are always state-of-the-art devices, it also, to a certain extent, makes the choice more difficult for the homeowner. There are so many aspects to compare that many potential buyers just ask around and purchase the thermostat their friends are recommending. But to really get the ideal thermostat for your home and circumstances, you have to do some research and compare the aspects that are crucial for your circumstances. 

To assist you with this research, we’ve looked at two of the top available thermostats and now share our findings with you. The two thermostats are the Ecobee4 and the Honeywell RTH9585WF.

The differences and similarities between the Ecobee 4 and the Honeywell RTH9585WF

The differences between the two thermostats don’t necessarily make the one better than the other, but you may find that a specific aspect automatically excludes one of the thermostats as it doesn’t fit your circumstances or existing HVAC system.  

We’ll discuss the differences and similarities between the Ecobee4 and Honeywell RTH9585WF thermostats in detail, but to give you a birds-eye view of the most important differences and similarities, let’s first have a look at the following table, list and chart: 

Table with most important differences

This table briefly provides you with the main differences between the Ecobee and Honeywell thermostats. 

Ecobee4 Honeywell RTH9585WF
Compatible with Apple HomeKit Not compatible with Apple HomeKit
Offers many geofencing capabilities Does not have many geofencing capabilities
Uses room sensors to know your location and the temperature around the entire house Does not use room sensors 
Can be installed without a C-wire You need a C-wire to install
You cannot change the display You can customize the display color 
Cannot learn your habits Learns your habits and can program itself

List of most important similarities

The Ecobee and Honeywell thermostats also share similar characteristics. As with the differences, we list the most important similarities here and will later discuss some of them in more detail.  

Both thermostats 

  • have mobile apps, 
  • can be activated and controlled with voice commands,
  • can be programmed,
  • offer extensive possible schedules,
  • will power over 95 percent of the common HVAC setups,
  • offer a DIY installation and set-up possibility,
  • have touchscreen displays in 480×480 resolution, and 
  • are capable to handle multiple users controlling the settings.

Specifications Chart

This chart indicates most of the specifications you will be looking at when you have to choose a thermostat to purchase. For your convenience, the specifications that differ, are listed separately from the specifications where there is no difference between the two thermostats.

Ecobee4 Honeywell RTH9585WF

Color of unit Black only Silver only
Dimensions of unit 4.29×4.29×1 inches 3.5×4.5×0.88 inches
Display options on screen None 12 preset colors plus sliders
Can use Apple HomeKit Yes No
Work with SmartThings Yes No
C-Wire substitute PEK None
Remote sensors Room sensors None
Voice and audio abilities Yes Only limited abilities
Habit learning No Yes
Warranty  For 3 years Only for 1 year
Price Check on Amazon Check on Amazon

Screen resolution  Touch-screen : 480×480 Touch-screen : 480×480
Bluetooth function No No
Operate wireless  Yes Yes
Amazon Alexa capability Yes Yes
Can use Google Home Yes Yes
Wink compatibility Yes Yes
Mobile App available Yes Yes
Website access Yes Yes
Energy reports available  Yes – monthly Yes – monthly
DIY installation possible Yes Yes

Aspects to look at in more detail before you buy

We’ll now discuss in more detail the aspects to look at when choosing a thermostat. Although we are comparing the Ecobee4 and Honeywell RTH9585WF thermostats in this article, you use, in principle, the same aspects and criteria when you compare any model or brand with another. 

DIY installation

The manufacturers of both the Ecobee and the Honeywell thermostats claim that their thermostat models have a simple DIY installation process. 

In a way, DIY installation should be the obvious way to go – you are only installing a thermostat. You need a few screws to apply the thermostat to the wall and you have to connect a couple of copper wires. Generally, this can be done by just about anyone. However, if you want to, you can have the thermostat installed by a professional. 

If you want to go the DIY route, make sure that easy to follow instructions regarding the connection of the wires are included in the box. 

Installation procedures

As the basic installation process is the same for Ecobee and the Honeywell thermostats, it doesn’t matter which one you are choosing. With either choice, you just have to decide whether you are going to do the installation yourself or are you going to get a professional to come and do it for you.  

If you’ve chosen the Ecobee4, you can add the thermostat to your wireless network after the thermostat’s set-up is completed on the touch-screen.  You can then also sync the Ecobee mobile app and further change settings.

If you’ve chosen the Honeywell thermostat, you will also have to add your email address to enable alerts after you’ve synced the app. The Honeywell mobile app will get you to push alerts for certain aspects, but the email alerts are crucial and more in detail. 

With all this said, it is clear that the installation and set-up of the two thermostats are virtually identical and therefore should not influence the choice you have to make before purchasing the new thermostat. 

Smartphone apps

Both the Ecobee and Honeywell thermostats offer great smartphone options and app control. They let you specify the temperature you’d like your home to be at and the smartphone apps duplicate this functionality.  They also provide additional information on their screens. 

On both of them you can, for instance, read the outside temperature. They both give you feedback on your HVAC’s energy usage. 

To be able to communicate with your smartphone they connect with Wi-Fi to your wireless network. They both supply reports on your energy usage, and both can be controlled by your voice if you use compatible digital programs such as Amazon Alexa.


Both these thermostats are programmable. You can, for instance, set the times you know nobody will definitely be in the house, and then program the thermostats to have the heating switch on only when needed. The set programs can easily be overridden if someone should come home early. 

Compatibility and portability

.Although the Honeywell thermostat is compatible with a broad range of heating systems which include heat pumps, you need a C-wire to make it compatible. A C-wire is a low-voltage return wire that’s essential for powering the thermostat.

It is also good to use a C-wire with the Ecobee4, but as it also works with Apple HomeKit, and comes with a power-extender kit you can make alternative arrangements if your system doesn’t have a C-wire.

Both the Ecobee and the Honeywell thermostats can be placed in the same hole in your wall where your previous thermostat has been. However, neither is suitable for use as a portable thermostat.  

Design and price

The Ecobee and Honeywell thermostats look very different. The Ecobee4 thermostat is a dark super ellipse and the silver rectangle look of the Honeywell RTH9585WF is more like a conventional thermostat with its menus and lots of data that can be displayed on the screen simultaneously. It can be said that Honeywell’s design is perhaps more functional than Ecobee’s design.

Although the Honeywell thermostat is somewhat cheaper than the Ecobee thermostat the price difference is for many potential purchasers not a factor. It doesn’t influence their choice too much. The difference in price is about $30

Energy Conservation 

For most people, the reason to purchase and install a smart thermostat is that they want to save energy and money.

A well-programmed thermostat saves you money because it controls your HVAC devices to be active only when needed. 

The Honeywell RTH9585WF system can save you, on average, between 20 and 25 percent on your utility bill. The savings are possible because the RTH9585WF thermostat will learn your habits and control your HVAC devices accordingly. 

If, for example, you wake up every day at 7 am and turn your heating on to warm the house to 72 degrees, the thermostat notices your daily pattern. Once it has recognized it as a pattern, it will kick on the heating system a few minutes before you wake up at 7 am to ensure that your home is 72 degrees when you get up. By learning your habits and making the necessary anticipations, your energy consumption is lowered and you are saving money. 

The Ecobee4 can save you up to 23 percent on your heating and cooling bill. The Ecobee thermostat doesn’t learn your habits but saves you energy with its geofencing, room sensors, fine-tuning abilities and scheduling possibilities. 


Smart thermostats’ sensors make your life and the temperature control in your home easy. 

The Honeywell thermostat uses a lot of different sensors to provide you with weather reports, ambient temperature and internal temperature. 

The Ecobee4 does not have all these sensors but offers a very efficient room sensors system. You place these little sensors around your home in places where the thermostat is not located. These sensors then send status updates to the thermostat. Instead of relying only on the temperature sensor in the thermostat itself, the room sensors make it possible for the thermostat to adjust temperatures to suit the whole house. 


When you have to purchase a new thermostat for your HVAC system, it is in your best interest to have a look at different models and brands to find the thermostat for your unique circumstances. In this article, we’ve compared one model each of two different brands. As they are both very popular choices, we hope that we could make your choice easier. And again, remember that you can use the same aspects to compare any two or more thermostats with each other. 


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