Mini-Split Heat Pumps and Smart Home Integration

Both the Sensibo and Ambi Climate provide a way for a homeowner to better control their mini-split heat pump system.

Mini-split heat pumps, also referred to as ductless heat pumps, have become an energy efficient alternative to standard HVAC systems. The system consists of two parts, an outdoor compressor unit and an indoor air handler. The two components of the system are connected by refrigerant lines. During the summer, heat is removed from inside the home and it is released outside. In the winter, the process is reversed. The outside unit absorbs heat and releases it through the inside air handler.

There are significant advantages to a mini-split heat pump compared to other types of heating/cooling systems in a home.

• The system provides both heating and cooling. There are not separate furnace and air conditioner units
• In new construction, there is no labor-intensive ductwork to install; reducing cost. In older homes this ductwork may not be insulated, leading to wasted energy and higher costs for heating and cooling. In addition, the joints in the ductwork may not be sealed, allowing heated or cooled air to leak into walls, ceilings, the home’s attic, etc. This again leads to wasted energy and higher costs for heating and cooling
• According to energystar.gov, because they transfer instead of generate heat, ENERGY STAR-certified ductless mini-split heat pumps use 60-percent less energy than standard home electric resistance-based heating systems
• Again, according to energystar.gov, mini-split heat pumps can save on cooling costs by 30 percent compared to conventional room air conditioners
• Depending on the model being installed, multiple indoor units may be able to be connected to a single outdoor unit
• The separation of the indoor air handler from the outdoor compressor unit reduces noise when compared to window air conditioners
• For added comfort, different heating/cooling set points can be set in different rooms of a home
• Unoccupied rooms can be shut off from heating/cooling to save on energy use and the cost of heating/cooling.

However, before you throw away your old forced air heating/cooling system and replace it with a mini-split heat pump, there are a few things to be aware of:

• Mini-split systems are not inexpensive, especially compared to the cost of a window air conditioner. I recently priced the installation of a mini-split system for a single room in my home and the cost exceeded $5000.
• Indoor units are typically mounted high on a wall and are not what I would refer to as “decorator friendly.” There are some indoor units that can be mounted within a ceiling, but these can add to the cost of installation
• Like any HVAC system, mini-split systems need to be carefully sized to a home. This typically means involving a professional installer, which adds to the overall cost. In addition, while a mini-split system is much simpler to install than a ducted HVAC system, the system’s warranty may be violated by a DIY installation.

Smart Home Integration with an HVAC System

There is a great deal to be gained by integrating an HVAC (heating, ventilation, and air conditioning) system with a smart home processor/hub.

1. The thermostat can be set back based on occupancy. When nobody is home both energy and money can be saved by setting back the thermostat. The normal set point can be restored as soon as a family member comes home
2. Since a mini-split system provides for different settings in different zones of the home, even more money can be saved by setting back an individual zone when that area of the home isn’t occupied
3. Using a product like RoomMe, which tracks peoples’ locations in a home through their smart phones, the set point of a mini-split system can automatically be adjusted to a person’s personal preference in the area of the home where they are currently located
4. Again, to save energy and money on utility bills, the set point can be adjusted based on the weather forecast. In the spring and fall when temperatures can be cool at night but warm during the day, the system can be set to warm the house up first thing in the morning. Then the set point can then be set back to take advantage of warming outside temperatures during the day.

The challenge of implementing the above use cases with a mini-split system is that there isn’t a single, centralized, thermostat that can easily be replaced with a smart thermostat. Instead, each zone of the mini-split system has its own built-in thermostat that is fully integrated into the room unit and cannot be replaced with one that is compatible with your smart home processor/hub. Fortunately, third-party companies have come up with a solution to this problem.

Sensibo and Ambi Climate both offer products that allow smart home processors/hubs to integrate with a wide variety of mini-split systems. In addition, they also allow integration with a wide range of heat pumps, in-room air conditioners, and window units. Throughout the remainder of the article I will simply refer to mini-split systems, but it is important to remember that Sensibo and Ambi Climate devices can control many other types of air conditioners and heat pumps besides just mini-splits.

Sensibo

Sensibo also offers both Sensibo Sky and Sensibo Air for controlling mini-split, heat pump, and air conditioning systems that are operated by a remote control. Both products allow you, using your smart phone, to control your mini-split system from anywhere, can automatically turn the connected mini-split system on/off through geo-location, offer smart temperature settings, and seven-day scheduling.

The Sensibo Air also offers compatibility with Apple HomeKit, is slightly smaller (approximately 2-5/8” wide x 2-5/8” long x 3/4” high) and is compatible with their optional Room Sensor that can be used to determine if a room is occupied, or not. Finally, according to Sensibo, the Sensibo Air includes a more advanced chipset.

Both products are small and would easily fit into a contemporary décor with their white plastic cases and dark plastic IR windows. Like the Ambi Climate Mini and Ambi Climate 2, the Sensibo Air and Sky control mini-split, heat pump, and air conditioning systems by sending IR commands to the device.

Sensibo provided me with a Sensibo Air and a Sensibo Room Sensor to test for this article. Throughout the remainder of the article I will simply refer to the Sensibo Air, instead of both the Sensibo Air and Sky as the products are primarily the same, other than the differences I’ve already pointed out, and all my testing was done with the Sensibo Air.

Sensibo appears to be compatible with a broader range of mini-split, heat pump, and air conditioning systems than Ambi Climate. I base this on the fact that the Ambi Climate Mini and Ambi Climate 2 will only work with mini-split systems that have discrete power on and power off IR commands. Also, the Sensibo Air will work with mini-split systems that have either discrete power on/off commands or power toggle commands.

I don’t have a way to validate whether or not Sensibo truly has a larger compatibility list than Ambi Climate. However, another Crestron programmer helped me test the Crestron driver I wrote for the Sensibo Air. He has a Mr. Cool mini-split system and only Sensibo is compatible with it. Like Ambi Climate, Sensibo offers a tool for checking compatibility on their website.

Included with the Sensibo Air are a power cord, plug-in power supply, and a small double-sided adhesive pad for wall mounting the Sensibo Air. The Sensibo Air also has a keyhole slot in the underside of the case for mounting the device to a wall using a screw. Printed on the packaging are the basic instructions for downloading the Sensibo app and for contacting Sensibo support if you need assistance.

Sensibo Operation

After the very simple Sensibo app installation process on an iPhone or Android device, The Sensibo Air provides complete control of a connected mini-split system including the ability to:

• Select between different operating modes, including cool, heat, fan only, dry, and auto
• Select the set point of the mini-split system
• Select between different fan speeds including quiet, low, medium low, medium, medium high, high, and auto
• The ability to control the swing of the mini-split system including settings for stopped, fixed top, fixed middle top, fixed middle, fixed middle bottom, fixed bottom, range top, range middle, range bottom, range full, horizontal, and both. Swing is the ability of horizontal flaps to move up and down to disperse the air in the room.
• The ability to control the horizontal swing of the mini-split system including settings for stopped, fixed left, fixed center left, fixed center right, fixed right, fixed left right, fixed center, range center, range left, range right, and range full. Horizontal swing is the ability of vertical flaps to move left and right to disperse air in the room
• The ability to control the mini-split system’s lights including settings for on, off, and dim
• The ability to use geofencing to turn the system on/off when users arrive/leave
• The ability to create schedules that can turn the system on/off, change the set point, change the fan level, and more. Schedules can be setup for different times and on different days of the week so, for example, you can have separate weekday and weekend schedules
• The ability to create a timer that turns the mini-split system off after a specified period of time
• The ability to view graphs of the temperature, humidity, and “feels like” temperature in the room where the Sensibo Air is located
• The ability to view a log of system events that have taken place; such as when the system was turned on and when the mode was changed
• The ability to add additional people as users of the Sensibo app that can control the mini-split system
• The ability to calibrate the Sensibo Air’s internal temperature and humidity sensors
• The ability to control what notifications you will be sent including notifications of error conditions, general system operation, and promotional information about Sensibo sales and product offers

Sensibo also offers an advanced operating mode called “Climate React.” Climate React offers the ability to, for example, setup dual set points so the system will automatically change the mode to air conditioning when it is too warm and change the mode to heat when it is too cold. Climate React can turn the system on/off, change the operating mode, change the fan level, and change the set point in response to a change in the actual temperature, the “feels like” temperature, or the humidity. So, for example, during a family vacation the mini-split system could be placed into dry mode when the humidity gets too high to avoid the possible growth of mold in a home.

Sensibo offers an optional, battery operated, Room Sensor that is used as an occupancy sensor in the room where the mini-split system being controlled by the Sensibo Air is located. The Room Sensor is easily installed by choosing the Sensibo Air that it will be paired with, scanning the QR Code on the bottom of the device, and pulling the small plastic tab which will allow the replaceable, internal battery to begin powering the device.

With the Room Sensor installed, the Presence React function can be configured in the Sensibo app to turn the mini-split system on/off and enable/disable Climate React when someone enters or exits the room. The amount of time after motion is last detected, before the Room Sensor triggers that the room is unoccupied, is also adjustable. Finally, the scheduler can be used to, for example, disable Presence React at night so the mini-split system in a bedroom can’t be turned off by a lack of motion when people are sleeping.

Sensibo also offers a subscription based “Sensibo Plus” program. Sensibo Plus costs $4.99 per month or $2.99 per month when purchased on an annual basis. Sensibo Plus offers:

• Real-time weather and air quality notification that will help cut back on energy use
• The ability to save money with energy-saving tips so your mini-split system is always set to efficiently Cool or Heat
• Reminders to clean, or replace, your mini-split system’s filters on time to keep it operating efficiently
• The ability to turn Climate React on, or off, based on geofencing
• The ability to view graphs and logs on a weekly and monthly basis. Without Sensibo Plus you can only view the graphs and logs for the current day
• Perform a health check that analyzes the performance of your mini-split system
• Get special promotional discounts from Sensibo
• Sensibo Plus extends the warranty of your Sensibo Air by an additional year.

Integrating with Sensibo

Sensibo supports integrations with Amazon Alexa, Google Assistant, IFTTT, Siri (Sensibo Air Only), and an open API so programmers can create their own integrations. The Sensibo Air acts as a thermostat within the Amazon Alexa ecosystem. This allows a homeowner to use simple commands including “Alexa, turn on the <room name> air conditioner” or “Alexa, increase the temperature in the <Room Name> by X degrees”.

IFTTT can also be used to control the Sensibo Air. IFTTT provides the ability to turn the connected mini-split system on/off, set the operating mode, adjust the set point, and set the fan level.

Using the Sensibo open API I created a Crestron driver to allow a Sensibo Air to be controlled from a Crestron smart home 3-Series or 4-Series processor. The driver can be downloaded from my GitHub here.

Unlike the Ambi Climate, the Sensibo API doesn’t implement OAuth2 security but that doesn’t mean that the API isn’t secure. To use the API you begin by obtaining an API Key. To accomplish this, you will need to use your username/password and login to the Sensibo website. There is a login link in the menu at the bottom of the main page of the website. You will then be presented with a screen that shows you your Sensibo devices. In the upper left-hand corner of the screen is a menu icon and selecting it will present you with an option to create an API Key. The API Key is then included in a parameter field of the Crestron driver module and limits the driver’s access to only those Sensibo devices associated with the account used to create the API Key.

Next, you will need to obtain the ID of your Sensibo Air. In the lower right corner of the square that represents your Sensibo Air, when you are logged in on the Sensibo website, is a three-dot menu icon. Pressing this displays a drop-down menu. Press the “Advanced” option on the menu and then choose “Advanced Info.” The UID is the device ID of the Sensibo Air. The Sensibo Air’s device ID is then included in a parameter field of the Crestron module.

The driver provides full control of mini-split system connected to the Sensibo Air including:

• Power On/Off
• Changing Modes
• Controlling Fan Levels
• Controlling Swing
• Controlling Horizontal Swing
• Controlling the Mini-Split System’s Lights
• Turning On/Off Climate React
• Setting the Mini-Split system’s target temperature
• Providing Feedback on Temperature and Humidity measured by the Sensibo Air’s built in sensors

It is important to understand that not every mini-split system, heat pump, or air conditioner that will be controlled by a Sensibo includes every option in the module. It is up to the programmer who is including the driver in a Crestron program to only expose the options available for the homeowner’s mini-split system in the Crestron system’s UI.

Sensibo Air Suggestions for Improvement

Overall, the Sensibo Air is a well-designed and easy-to-use product that can optimize the operation of a mini-split system. The API allows the products to be integrated with an overall smart home platform. However, there is one way, I think, the product could be improved. Climate React needs a third set point that can be programmed to change the operation of a mini-split system. In this way, the first set point can control when it is too cold, and the mini-split system should change to heat mode. The second set point can control when it is too warm, and the mini-split system should change to cool mode. The third set point would sit between the original two and provide the ability to turn on the mini-split system’s fan to improve the comfort of the people in the room but save money by not changing to cool mode.

Ambi Climate

Ambi Climate offers Ambi Climate Mini and Ambi Climate 2 for controlling mini-split systems, which are operated by a remote control. Ambi Climate provided me with both to evaluate for this article.

The two models offer the same functionality. The primary difference between them is size. While the Ambi Climate 2 is not very large (approximately 4-1/4” wide x 3-1/8” high x 1-5/8”deep), the Ambi Climate Mini is a fraction of that size. In addition, while the Ambi Climate 2 is designed to be placed on a table or shelf, the Ambi Climate Mini can, in addition, be mounted on a wall.

One other important difference between the Ambi Climate Mini and the Ambi Climate 2 is the lifetime operating cost of the two models. While the Ambi Climate Mini is slightly less expensive than the Ambi Climate 2, the Ambi Climate Mini requires a subscription to access Ambi Climate’s smart AI features after an initial two-month trial period. A lifetime subscription is included with the Ambi Climate 2. The subscription is not expensive, at $2.99 per month, and I understand that companies need a continuing income stream to support the cost of their back-end cloud platform. But it is important to understand that this fee exists and including it as part of a purchasing decision.

Both models are aesthetically pleasing with an IR window on top, a white plastic body, and a wooden base. Both Ambi Climate models control mini-split systems by sending IR commands to the device in the same way the mini-split system’s remote control does. Because of this Ambi Climate devices can only work with mini-split systems that include discrete commands for different functions; such as power on/off.

Included with each product is a power cord, plug-in power supply, and a brief getting start guide (a full user manual is available here). The Ambi Climate Mini also includes a wall mounting bracket.

Set up of the Ambi Climate app very simple. The most important thing to remember is to make sure you have the manufacturer/model of your mini-split system along with the model number of the system’s remote control. The model number of the remote control can typically be found on the underside of the remote.

Ambi Climate Features and Functions

Ambi Climate provides a wide range of options for controlling your mini-split system:

• Comfort Mode – In Comfort Mode, Ambi Climate learns what temperature/humidity combinations you find comfortable, under what conditions you aren’t comfortable, and then automatically makes adjustments to your mini-split system to keep you comfortable. The system starts with a basic model and using the app you can provide feedback as to whether you are comfortable, or not. Over time the system will redefine the model to fit your individual preferences.
• Temperature Mode – In Temperature Mode, you select a target temperature for your room. Ambi Climate then uses AI and machine learning to optimize the operation of your mini-split system based on the temperature/humidity of the room and how your min-split system is affected by changing environmental conditions outside your home.
• Away Mode – In most HVAC systems, away mode is simply a temperature setback to save energy when you aren’t home. Ambi Climate goes beyond that by allowing for thresholds to be set for heating, cooling, or humidity when you are away. For example, in a humid environment a homeowner might set back their air conditioning system to save energy while they are away. However, this might result in high humidity levels in a home that could lead to the growth of mold. In Away Mode the Ambi Climate can monitor the humidity level and, if needed, use the air conditioning as a dehumidifier to reduce the amount of moisture in the air.
• Manual Mode – In Manual Mode, your system is controlled by simply setting a target temperature set point along with any other features your mini-split system may offer, such as the fan speed, louver angle, etc. Manual mode does not leverage any AI or smart features offered by the Ambi Climate
• Off Mode – This allows you to simply turn off your mini-split system. There isn’t a corresponding On Mode as selecting any of the above modes will turn the mini-split system on, if it is off.

The Ambi Climate app offers a number of other additional features:

• Full control of a mini-split system including choosing one of the above operating modes, fan level, swing, etc.
• The ability to choose how the Ambi Climate AI will control your environment to maintain your comfort
• The ability to create timers. For example, you can create a time when your mini-split temperature will be set back during the night. Timers can be triggered at a specific time and on specific days of the week. They can trigger a specific mode to be selected and the operating parameters of that mode; such as a specific temperature set point when Temperature Mode is selected.
• User Management – the ability to add additional users to the system
• Analytics – For those that want to dig into the details on the operation of their mini-split system, Ambi Climate offers a wide range of ways to examine the data. There are graphs of AC run time, average AC set point, temperature and humidity, and more. You can also dig into the details of how the system knows whether you are comfortable, or not.
• Geolocation – Ambi Climate can automatically set back the connected mini-split system when you leave home and restore it to normal operation when you arrive home, using geofencing and the GPS on your smart phone. The system is designed to support multiple users so it won’t set back the min-split system until every member of a family has left the house and will restore normal operation when the first family member returns home. There is a complete article on the process of setting up geolocation in the Ambi Climate knowledge base here.

Ambi Climate Integrations

Ambi Climate supports integrations with Amazon Alexa, Google Assistant, IFTTT, and an open API so programmers can create their own integrations. For example, the Ambi Climate Alexa skill supports commands for providing comfort feedback to the Ambi Climate AI system by saying “Alexa, tell Ambi Climate it’s too warm in <room name>” or “Alexa, tell Ambi Climate it’s a bit cold in <room name>”.

Similarly, through IFTTT you can select the operating mode of the Ambi Climate device, provide comfort mode feedback, and more. For convenience Ambi Climate has provided a wide selection of pre-made IFTTT applets.

Using the Ambi Climate, open API I created a Crestron driver to allow the Ambi Climate to be controlled from a Crestron smart home 3-Series or 4-Series processor. The driver can be downloaded from my GitHub here.

The Ambi Climate open API requires OAuth2 authentication. Normally this is a showstopper when writing a Crestron driver because a full OAuth2 implementation requires a port forward on the homeowner’s router to the Crestron processor; a significant security risk in itself. Fortunately, Ambi Climate allows a user to create their OAuth2 access token through a website form instead of having to programmatically support callbacks by adding port forwards to the router on the homeowner’s network. The form for creating the access token can be found here.

Ambi Climate has not completely removed the complexity of implementing the OAuth2 protocol. Their access token expires after 40 hours and the driver software needs to implement a token refresh process, or it will lose the ability to communicate with the Ambi Climate device. I chose to simply implement a timer that refreshes the token any time the processor is restarted and after every 24 hours of operation. I hope that this will prove reliable.

The Ambi Climate API includes rate limiting that limits the number of API calls 20 during any 10-minute period. A programmer using the Crestron driver I wrote, or any other driver based on the API, needs to keep this in mind. For example, a basic up/down arrow interface to adjust the temperature set point that sent a new set point to the Ambi Climate on each button press could fairly easily exceed the API call limit. In writing the Crestron driver for the Ambi Climate I limited the functionality I provided in the driver because of this.

Suggestions for Improving Ambi Climate Mini and Ambi Climate 2

Overall the Ambi Climate Mini and Ambi Climate 2 are well designed and easy to use products that can optimize the operation of a mini-split system. However, there are a couple of ways I believe the product could be improved.

It is a pet peeve of mine that when you run an app on a table it should be able to operate in landscape mode. Many people, including myself, have keyboards attached to their tablets and an app that is locked in portrait mode is a pain to use.

While this won’t impact most users the Ambi Climate API needs improvement. First, the API documentation is incomplete and doesn’t fully document the protocol. Without support from Ambi Climate it would have been exceedingly challenging to develop the Crestron-Ambi Climate driver I wrote. Second, none of the API calls return feedback on the new state of the Ambi Climate after a command has been acted on. To implement a driver properly would require a second command to obtain the Ambi Climate’s status after any command is sent. This cuts in half the number of commands that can be sent before the rate limit is exceeded. As mentioned above, implementing a temperature set point using up/down arrow buttons on a touch panel could also exceed the rate limit. I understand the desire to limit API calls, so the Ambi Climate cloud server doesn’t become overloaded. But, given the current state of the API the limit is very restrictive.

Conclusions

Both the Sensibo and Ambi Climate provide a way for a homeowner to better control their mini-split system. Ambi Climate offers more intelligent control but this feature comes at the price of a subscription with the Ambi Climate Mini. Sensibo offers an optional subscription. But, unlike the Ambi Climate subscription, it is optional; and no “must have” features are lost if the subscription isn’t purchased.

For the integrator, the Sensibo API offers much simpler, and complete, control of the customer’s mini-split system.

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