Larry Magid: Keeping cool with AC, evaporative coolers, fans and an app

I’ve been living in the Bay Area since 1981, and until about four years ago, it never occurred to me to invest in air conditioning. But recent extreme heat and the risk of smoky air from fires got me to rethink that decision.

About three years ago, on a very hot and smoky day, I escaped the heat and air pollution by working on my laptop from the backseat of my air-conditioned electric Tesla Model 3 which was parked in our garage. Later that day my wife joined me, and we watched Netflix on the car’s screen. Do not do this in a garage in a gasoline car. It could have deadly consequences.

Sitting in our car is not a good long-term solution, so my wife and I recently invested in a mini-split system, which not only cools our living room, kitchen, dining area and upstairs bedroom, but promises to heat them come winter. I’ll spare you the technical details but if you’re curious how it’s possible for one system to both heat and cool, visit larrysworld.com/heatpump.

Split system

A split system consists of a heat pump, sometimes called a condenser, which is placed outside the house. Inside there are one or more indoor units or “air handlers,” depending on how many rooms you want to heat and cool. The indoor units are typically mounted on walls, but they can be on the floor or the ceiling. Unlike traditional heating and cooling systems, there are no air ducts, but there is a bundle of cables and narrow pipes that provide power and communications, deliver refrigerant and handle drainage. In my installation these were encased in an approximately 4-inch-wide housing that cover and hide the cables. Our contractor painted them to match the house so, while they are visible, they are not unsightly.

We opted for two indoor units. Our downstairs is an open design, so we put one 18,000 BTU indoor unit between the living room and kitchen to handle the entire living, cooking and dining area. We installed a 9,000 BTU unit to cool and heat the upstairs bedroom, which gets quite hot but is a lot smaller than our downstairs area.  The outdoor heat pump is rated for 36,000 BTUs and able to handle a up to four indoor units should we later decide to add one or two. Both the outdoor and indoor units are extremely quiet, especially if you have the fan on low or medium.

Multiple bids and tax credit

We wound up getting a Mitsubishi Split system after getting bids from multiple contractors including one affiliated with Costco that offered Lenox systems at a much higher price even after the Costco gift card that came with the deal. The bids ranged from $12,500 to about $20,000 for what was, essentially, the same level of equipment. By scouring the web, I got a rough idea of what the devices themselves cost (none of my bids broke that down) so I went with Mountain View-based Calvey Heating and Air, which was the low-bidder but also highly recommended by a friend. That $12,500 bid much more than covered the cost of the equipment so, as far as I could tell, the company, which did a great job, still made a decent amount on the project. I have limited experience with this type of job, but my sense is that there is a lot of wiggle room when it comes to pricing.

Because the unit I installed also heats, we’ve decommissioned our old gas furnace, which qualifies us for a $2,000 federal tax credit thanks to the Inflation Reduction Act that President Biden signed in 2022. There may be other rebates depending on where you live.

Fans, Evaporative Coolers and Space Heaters

Additional indoor split units cost about $4,000 each with installation, so to save money, we decided to use space heaters in our other rooms in the winter and fans or evaporative coolers in the summer. None of our rooms have the type of windows that can accommodate a window air conditioner or easily handle a portable AC, which needs a window or hole in an outside wall to vent. So, for my small home office, I opted for an evaporative cooler that you fill with water to help cool the room. They’re not as effective as air conditioners, but they don’t require venting, and they are generally a lot less expensive and use less energy than window or portable air conditioners. I wanted one that I could pick up locally, and the best one I could find was a $69 Arctic Air Chill Zone XL that I have sitting near my desk. It’s not ideal but it is keeping me cool as I write this column while it’s 85 degrees outside. There are larger evaporative units available online that are advertised for cooling entire rooms. Evaporative coolers also humidify the air, which can be good in dry climates but not in humid ones.

Wi-Fi and app control

One of the reasons I opted for Mitsubishi is because they have an optional Wi-Fi adapter that supports an app and Alexa voice control. But the adapter, which requires professional installation, wound up adding $500 to the cost for both indoor units. Plus, the online customer reviews and experience of my neighbor who has the Mitsubishi “Kumo Cloud” Wi-Fi adapter, were less than stellar. So, instead I went with Sensibo, which is a device and app that works with almost any air conditioning system that has an infrared remote control, including window and portable systems. Sensibo controllers start at $87, which is far less than the Mitsubishi solution and do pretty much the same thing, though, unlike the Mitsubishi app, they are not integrated into the device but simulate the remote control from the smartphone app. The Sensibo app is easier to use and more intuitive than the Mitsubishi remote, and because it’s on your phone, you can use it in a dark room, which is handy if I want to control the bedroom device while my wife is sleeping. You can also use it away from home. One option is the $140 Sensibo Air PRO that also does indoor air quality monitoring. Sensibo units are often discounted on Amazon and sensibo.com, so you might find them at a lower price.

I would prefer going back to the days when we didn’t need air conditioning in the Bay Area, but our climate is changing, and there are days when it’s the only way to be comfortable at home. In an effort to spare the grid and our electric bill, we’re using it sparingly but glad that we have it and also glad it allowed us to ditch our gas furnace. Now I’m looking into solar.

Larry Magid is a tech journalist and internet safety activist. Contact him at larry@larrymagid.com.