It’s July in southern Indiana which means it’s hot and humid outside. But this year it’s worse because there’s a heat dome over us and while both we and the corn in the fields are sweating, air conditioning units are working overtime to keep our homes cool and comfortable. AC units use a lot of electricity which can lead to dread when the electric company bills show up in the mailbox. Is there anything you can do to make your AC run less while still keeping your house cool? Mistbox is a gadget that has been designed to help you save up to 30%, depending on where you live, on your monthly electric bill during the hot summer months. Let’s take a look. Mistbox is a device that connects to your outdoor AC condenser unit and sprays a fine water mist around it while it is running. The mist pre-cools the air around the AC, which helps it be more efficient and the air coming out of your registers will be a few degrees colder than without the Mistbox. Here’s a video that does a good job of explaining the process: Mistbox main unit with attached filter AC charging adapter with interchangeable plugs Mist sprayer bars Attachment hardware User guide The Mistbox system consists of a plastic control unit, a sprayer arm assembly and an app.

The control unit has an LCD display with three buttons, a WiFi antenna, water filter and a water intake connector. On the back of the unit is a power port that can be used to charge the controller’s battery. The Mistbox controller also has a solar panel on top which will keep the battery charged if your AC unit is in a location that receives a few hours of sunlight each day. Mistbox sells an auxiliary solar panel can be added to the unit by plugging it into the power jack on the back of the controller. Installing the Mistbox is pretty painless if your AC unit is located next to a water spigot and gets a signal from your home wireless network. The unit comes with everything you need for the installation except for a hose that connects from the water spigot to the connector on the Mistbox.  I happened to have a very short section of hose from an old hose reel that worked perfectly for this application, but you can use a regular length hose just as well. To install the Mistbox, you first attach the controller to a corner of your AC unit.

You can do this with screws or with zip ties. I used zip ties. One end of the sprayer bar assembly attaches to the bottom of the filter on the control unit and then using the included clips or zip ties you can  attach the sprayer arms to the sides of the AC unit so that the spray nozzles are all pointing away from the air conditioning unit. york central air conditioning troubleshootingThe four sprayer arms are connected with a thin hose that can be pushed into the arms to adjust the length. belt for ac unitThe installation process took me only about 20 minutes or so to complete, so it’s really easy. a/c heat recovery unitI spent more time looking for a hose than actually attaching the hardware to my AC unit. The final step in setting up the Mistbox requires that you install the Mistbox app on your Android or iOS device.

The app will walk you through the steps of setting up the control unit to connect to your home’s wireless network. I had a little trouble with this step, but after a couple of tries, I was up and running. The app is easy to use and shows the current status of the unit, last time it was updated, and the local temperature. Dragging up on the picture of the AC unit will let you scroll through a timeline that shows how long your AC unit was running at different times during the day. The app has a status screen like the one you see above on the left. This screen shows the current status of the unit along with info on the battery level, filter and water saving mode status. The settings screen will let you toggle the misting option on/off, water saver mode on/off and set the misting temperature trigger (75 – 90°F). The savings screen takes several weeks before it starts showing info. The info is based on the information that you submit during the setup process about your power company and the price per kWh.

I’ve been using the Mistbox for a couple of weeks and still don’t have any savings info, but I’ve added the image above as an example of what I should be seeing after about a month of use. During the time that I’ve been using Mistbox, I’ve noticed that my AC unit has been running less than before I installed it. I’ve used my Nest thermostat app data to compare how much time my AC unit runs on days using the Mistbox with days when the Mistbox has been disabled. My testing hasn’t been very scientific since there are a lot of factors that can change how much the AC runs like temperature, humidity, wind, which are not identical every day. But I tried comparing similar days as best as I could and found that my AC was running an hour or so less on the days that the Mistbox was enabled. Again, I can’t really promise that you will have the same results. Depending on where you live you could have better or worse results. In addition to the AC not running quite as much on days with the Mistbox enabled, I noticed that the air coming out of my registers was noticeably colder whenever the Mistbox was misting.

In the beginning, I thought it was my imagination, so I got out my handy dandy IR thermometer and pointed it down one of the registers in my floor. With the AC and Mistbox running, the air was 3-4 degrees cooler than when the AC was running without the Mistbox. We all know that air conditioning units are exposed to the elements / weather day in and day out, 365 days of the year. But the biggest concern for some people is the potential for calcium build up or rust due to increased water exposure from misting. When I asked about these concerns, Mistbox agreed that while untreated water could indeed cause such issues, their product comes with a high-quality filter which guards against corrosion. The filter must be replaced annually ($29.99) and is rated for any municipal water supply that follows EPA guidelines, which is a maximum hardness of 500 PPM (parts per million) of dissolved solids. Mistbox does not recommend using their product with well water or with water that has a hardness level above 500 PPM.

If your water is above that hardness level, they recommend using a secondary filtration system. Mistbox uses sound and electro-magnetic field to detect when the AC unit turns on so it can start misting. If the outdoor temperature is at or above the set trigger temperature in the app, misting will start. The unit doesn’t mist the whole time the AC is running, but cycles on and off. I wondered about water usage, so I bought a cheap water meter from Amazon that I placed between the water coming out of my spigot and the Mistbox control unit. Unfortunately, the battery in the meter died after collecting info for a week, so I lost all that data. I contacted Mistbox to ask about water usage and this is what they told me: Mistbox is misting is 0.12 gal/min or 7.2 gal/hr.  It equates to pennies a day in water consumption even in places with expensive water. Water saver mode just makes Mistbox cycle the misting off more regularly during longer AC cycles.  It uses about a third less water in water saver mode while still producing about 80% of the benefit.

Water usage is the main thing about the Mistbox that I don’t like. But it’s not the price of water that bothers me, it’s all the water that ends up on the ground. I live in the woods, so my yard is mostly sticks, rocks, leaves and weeds with a little grass. The area around my AC unit is mostly bare ground. Even with the water saver mode turned on, the area around my AC unit remained wet and kind of muddy. Since the AC unit is located next to a wall of my walkout basement, it makes me nervous that all the water will somehow seep through the wall and might eventually cause a moisture or mold problem. Mistbox says it can cut your energy bills during the hot summer months by as much as 30%. That promise comes with a few conditions that have to be met. In order to earn the most savings, you need to live in a dry location. Humid locations like mine will still see improvement using the Mistbox, but not as much as other areas. And of course, you need hot weather for the AC to run. Saving money and using electricity more efficiently is something we should all be concerned with.