The BroadLink RM4 Mini is an affordable means to add IR capabilities to your smart home setup. With more than 50,000 IR codes on Cloud, chances are high that you can find a suitable one to control your IR devices like TV, set-top box, fan, radio, air conditioner, etc. I already had a BroadLink RM4 Mini in my living room for the TV and set-top box and I got another one for the bedroom to make the KDK fan and Mitsubishi Electric air conditioner smarter by allowing me to control them over the Internet. To maintain a consistent bedroom temperature, I got the HTS2 temperature and humidity sensor cable to go along with the RM4 Mini. In total, they cost me S$32.40 from Shopee.

What are you using it for?

I am on a little quest of finding a cost effective way of making my air conditioner smarter. I like to remotely control it using smart assistants like Amazon Alexa or via mobile when I am at home or outside. A stretch target would be the ability to maintain the room’s temperature consistently around a certain value (e.g. 25 degrees celcius) regardless of the weather (e.g. raining, warm night, thunderstorm).

I’ve tried specialised devices like air conditioner controller from Ambi Climate (i.e. Ambi Climate 1, Ambi Climate 2) and Sensibo (i.e. Sensibo Air). They are priced averagely around S$150.

With the BroadLink RM4 Mini and HTS2 combination, I hope I can achieve similar capabilities (like Ambi Climate and Sensibo) at a fraction of the cost.

BroadLink RM4 Mini

Unboxing the BroadLink RM4 Mini

Within the small package, you will find:

BroadLink RM4 Mini IR Universal Remote
USB power cable
Wall mounting accessory
Quick setup guide

Taking a closer look at the RM4 Mini

The glossy top cap hides the IR components. Near the center is the LED indicator.

The BroadLink RM4 Mini is a tiny little device. Compared to the Coca-Cola Classic Mini can (180 ml), the RM4 mini is slimmer and shorter.

At the front is the LED indicator to inform you about the operation status of the device. On the rear is where the microUSB power input and reset button is located. I like having an actual depressible button instead of the pin hole design that I had to dig for a paper clip. This is an improvement over the previous version of the RM4 Mini.

The glossy top cap hides the IR components like the sensor and emitters.

BroadLink HTS2 Temperature and Humidity Sensor Cable

The BroadLink HTS2 Sensor accessory can only be used with the BroadLink RM4 Pro and RM4 Mini currently. It enables the RM4 Pro or RM4 Mini to sense and log the temperature and humidity of the area it is deployed in.

The HTS2 cable can also be used to deliver power to the RM4 Pro and RM4 Mini. It is one (1) meter in length so you might need USB extension cable if you intent to deploy it further from power source.

Using the BroadLink RM4 Mini and HTS2 as smart aircon controller

In fact with just the BroadLink RM4 Mini, it is already possible to control the air conditioner remotely as it is a universal IR controller. I can control the temperature, mode (e.g. dry, cool, fan), fan speed (e.g. low, medium, high) and others if your aircon supports it.

With the additional HTS2 temperature and humidity sensor accessories, it is possible to set up routines like setting to a lower temperature when the room temperature is above a certain value. More than one routine can be configured.

Surprised to find an experimental feature – AI comfort temperature.

Other than manually setting routines, there is an experimental “AI comfort temperature” mode where it maintains the room at the desired temperature by varying the aircon’s temperature and fan speed periodically.

The hourly temperature and humidity is logged. Pretty useful.

It also logs the hourly temperature and humidity for the past 24 hours. The user interface could be improved by showing the entire graph in a single screen instead of having to scroll left and right.

How does it compare to the Ambi Climate and Sensibo?

Pro – Works as a smart aircon controller and more

It definitely qualifies as a smart aircon controller. In fact, it can also control other devices in its vinicity which Ambi Climate and Sensibo cannot do. I can create routine such that the aircon and fan can work together to cool down the room faster. I can also save money by switching off the aircon and switching on the fan to circulate the cool air when I am in deep sleep.

Pro – Climate Control is free

Both Ambi Climate and Sensibo have means to maintain the room at a desired temperature but this feature is either not offered for their entry level device or requires subscription. However, BroadLink offer this as a free experimental/ lab feature.

Con – Lack power state tracking

Although it works as a smart aircon controller, it lacks a particular feature that Ambi Climate and Sensibo has. That is, the ability to track the power state of the aircon. Ambi Climate and Sensibo works by actively listening for IR signals from the aircon remote. If you switch on the aircon using the physical remote, it sees the signal and registers that the aircon is switched on.

Although it does not really cause issues, it is just a small nuisance to see that the aircon is switched on while the app reflects it as off.

Conclusion

I am extremely pleased to learn that the BroadLink RM4 Mini and HTS2 sensor cable is able to control the air conditioner via Wi-Fi at a fraction of the cost of Ambi Climate or Sensibo.

Other than controlling the aircon, it is also capable of controlling other IR devices like the TV, set-top box and fan in the vicinity.

Last but not least, it is able to maintain the room’s temperature at my desired temperature via the free AI Comfort Temperature feature.