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Electronics whiz creates freeze alert device for peace of mind

Logan Stewart sells his Freeze Alert Plus units at Bueg's Ace Hardware in Detroit Lakes, where he works and pictured here, as well as online at his product's website, The units sell for $80 each, with $10 of that going to the Detroit Lakes High School robotics team. Stewart is the adviser of the team. (Marie Johnson / Tribune)1 / 2
The Freeze Alert Plus connects to a WiFi router and is constantly sending information about weather conditions and power outages to the Ther-Monitor website, which owners of the units can check from anywhere, any time. (Marie Johnson / Tribune)2 / 2

DETROIT LAKES, Minn. — Tired of trudging back and forth to his pumphouse all winter to keep an eye out for weather-related damage, Logan Stewart of Detroit Lakes started to wonder if maybe there was a way to get technology to do the legwork for him.

He began thinking about it more seriously after customers at Beug’s Ace Hardware, where he works, started asking for something that sounded just like what he wanted himself — something that would allow them to remotely monitor their homes and other properties for potentially urgent situations like freezing temperatures.

Stewart was aware of a couple of existing products that almost fit this bill, he said, but they weren't quite hitting the nail on the head.

That's when he started working on what would become his invention, the Ther-Monitor.

“There seemed to be a lot of people asking for something like (Ther-Monitor),” Stewart said. “People like snowbirds, or who were going on vacation … They wanted to be able to monitor the temperature of their house so the pipes didn’t freeze, and things like that. And there wasn’t anything out there that did that (like Ther-Monitor does), through Wi-Fi and the internet.”

Once he recognized the need, he set out to meet the demand — and that’s where his background in technology really came in handy. Stewart is the adviser of the Detroit Lakes High School robotics team, and has had a lifelong interest in electronics and programming.

“When the other kids were buying Ataris, I bought a computer,” he said. “I’ve got quite a bit of experience creating things that work with other things.”

It took him six months of research and development to create the Ther-Monitor, a product that checks all of his desired boxes. It sends customizable email and text alerts to property owners (and their friends, neighbors, employees, etc., if they so wish) whenever there are freezing temperatures, excessive humidity levels or power outages. Those owners can get more information by going to any computer, smartphone or other device capable of pulling up a website, from anywhere in the world.

The invention is two-part, consisting of the Ther-Monitor website,, as well as a small companion unit that connects to a Wi-Fi router at the location being monitored. There is no app to install. Multiple units with the same owner can all be checked at the same time, and multiple devices can all check the same unit at once.

Stewart has been selling his hand-made invention for about a year, and he says the system has worked “flawlessly” and customer feedback has been great. People are buying the units for their homes, businesses, cabins, garages, guest houses, greenhouses, barns, coops and stables, wine cellars, dog houses and other buildings.

“People who are using it are loving it,” he said. For instance, Stewart said it saved a local landlord who had three heaters go out on the same day last winter.

One reviewer on wrote that she got a warning about high humidity underneath her mobile home: "I looked into it and sure enough there was a water pipe leak. If that had continued, I would have had a serious moisture, rotting and mold problem.”

Another wrote that Ther-Monitor helped keep his cows from freezing to death by alerting him to a low temperature situation in his barn.

Stewart says he’d like to expand the sale of his invention into other stores in the near future. And at the request of a Detroit Lakes restaurant, he’s developing another model of the Ther-Monitor, which will have a probe on it to monitor food temperature.

Find the Ther-Monitor

The Ther-Monitor units sell for $80 each, with $10 of that going to the Detroit Lakes High School robotics team. They’re for sale at Bueg’s Ace Hardware in Detroit Lakes and online at