Honeywell CMT927 Wireless

The CMT927 (or alternatively the CM927) is among Honeywell’s more controversial products. Fundamentally, it is a wireless thermostat with 7-day programming options and is capable of providing heating and cooling. However, it is not considered as one of their more durable units because its LCD screen is prone to problems.




However, it’s not all doom and gloom. The CMT927 is still fairly impressive in its own right. The feature which stands out most is the fact that it offers both heating and cooling. This is not standard among thermostats, which primarily focus on heating. Aside from that, the CMT927 can be programmed for 7 days for maximum convenience.

This thermostat also features a few different modes, giving you the option to adjust the temperature as per your needs. These modes include Auto, Manual, Holiday, Party, and Frost. Auto and Manual are self-explanatory. Holiday mode sets a certain threshold for the temperature and if it reaches beyond that, it will compensate by adjusting the temperature. Party mode is for keeping the temperature at a consistent level for a specific period of time.

It has built-in memory that keeps your settings saved, so if you are exchanging batteries, you don’t have to worry about losing your settings. It also has volt-free connections and energy-saving TPI controls.


How to Use

The CMT927 is fairly simple to use. You only need to insert the batteries, set the date and time, and select a heating program. There is a slider on the thermostat that you can use to decide which heating program you want. Each one is clearly labelled along the slider.



If you want to customise it a little, you can set the slider to the “PROG” option and make the necessary adjustments on the screen by pressing the buttons on the screen labelled “+” and “-” to increase or decrease the temperature, date, or day.


CMT927 Common Problems / Complaints

It is nigh impossible to discuss the Honeywell CMT927 without addressing the problems with the LCD screen. Honeywell’s products are typically well-received due to their reliability, but in the case of the CMT927, this does not apply.

There are many complaints that point out how unreliable the LCD screen is. Some people report problems after a few years, but it’s not uncommon for problems to spring up even just a few months after installation. This is also the same with the CM907. That’s not to say that every owner of this model will experience an issue such as this.

When a replacement is needed, some people prefer to go for the same model they had previously to ensure a fast, compatible swap over, but the screen issues for this unit are a widespread enough internal fault to give buyers that little bit more hesitation when considering re-purchasing this model. Even at a cheap price. However, as already mentioned, you may buy this model, in used or new condition and have no screen issues what so ever.


Cause of the problem?

Most common cause: The problem stems from moisture entering the thermostat from the walls, rendering the screen faulty, unreadable, or completely shutting off. The most common solution used is to remove the screen and use a hair dryer to get rid of the moisture.



Honeywell is known for its impressive line of products, and the CMT927 is no slouch at least in terms of features, as it provides great heating and cooling and a lot of freedom to customise settings. Being user-friendly is another appealing quality. However, the problems with the LCD screen make this thermostat fairly unreliable. Considering the price of Honeywell products, this (as of yet) officially unresolved problem taints the reputation of the CMT927.

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2 Thoughts to “Honeywell CMT927 Wireless”

  1. […] Although the programmer comes with a 1-year warranty, its screen sometimes glitches to show you an “internal fault” sign. This is where you get a blank display and the controls become unresponsive. This could mean two things: either the internal capacitors have failed, or the small lithium battery inside has gone flat. Another Honeywell thermostat that can suffer potential problems with the screen is the CMT927. […]

  2. […] to fix them below. But please be aware: Some thermostats, such as the Honeywell ST9400C, and the CMT927 do have issues that are fairly well known. Still, they are excellent units overall. And while some […]

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