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Temperature Sensor Secrets: How Can Freeze Sensors Help You?

freeze sensor This little guy can save you a lot of trouble!

Blizzards, ice storms, a polar vortex — this winter is shaping up to be VERY chilly! There's no time like the present to make sure your house is winterized. And what's the best way to make sure it's safe? Keep an eye on vulnerable parts, like the basement or the attic, with a freeze sensor. Here's everything you need to know about this handy little gadget.


Freeze sensors keep track of temperature using one of several possible mechanisms. Depending on what kind of house and what climate you're talking about — an Arctic yurt, an East Coast beach house, or a Washington State ski chalet — you'll want a different type of freeze sensor.

Indoor Pipes

frozen pipe

It may look fragile, but ice is strong—strong enough to break through metal. When standing water in a plumbing system is allowed to freeze, increased water pressure at the mouth of the pipe leads to structural failure, and the pipe will burst. Burst pipes aren't just a temporary technical nuisance—the ensuing water damage can lead to structural problems and mold infestations that wreak endless havoc on your house. It's more common than you'd think. Even if your house is insulated against the cold, one hole or drafty spot can compromise the whole thing. And houses in normally warm climates are often built to stay cool, so they can fall prey to this after just one freezing spell.

A well-placed freeze sensor prevents this by warning homeowners when temperatures in vulnerable spots (basements and attics, for example) fall below a crucial threshold. Some models, such as SimpliSafe Freeze Sensors, include Smart Alerts that find you wherever you are, so that you can take the appropriate action immediately should your heating system fail.

Outdoor Water Fixtures

frozen fountain

Have you got an outdoor pool, a fountain, a koi pond, or another water fixture subject to the elements? A pool or spa freeze sensor can let you know when you should start your winter maintenance routine. These sensors alert you when temperature drops beneath a critical threshold, and some even automatically turn on filter pumps to keep them from freezing. Recommended for all summer splashers, unless you want your pool to double as a skating rink.

Irrigation Systems

frozen faucet

Busy people with yards and gardens rely on irrigation systems to keep their plants verdant and healthy. But if a mild day becomes a cold night, an innocent sprinkler can transform into an ice-making machine, turning your lawn, your stairs, and even the surrounding street into a slippery tundra. This not only harms your plants: it can also be a safety hazard to drivers and pedestrians. A freeze sensor shuts off your irrigation system as soon as temperatures threaten to drop into Arctic territory. They're so useful that some towns legally mandate freeze sensors on all irrigation systems, in order to prevent dangerous situations and save water.

Frost Alarm

frozen grass

It's nice to wake up to the twinkle of frost on a winter morning — unless you're a farmer, in which case that image probably struck cold into your heart. For vegetable-heads, frost means ruined crops—to the degree where professionals and die-hard hobbyists might find themselves up every few hours checking the outdoor thermometer. That's no longer necessary with frost alarms, which monitor outdoor temperature and respond to signs of impending frost with an audible alarm and/or protective measures like watering or fog systems. Many maintain connectivity from far away, so they can be placed anywhere in a field or garden.


frozen grass

  • Don't put your freeze sensor in a drafty spot! The sensor records the local temperature, not the thermostat temperature, so a stiff breeze through a door or window might cause it to alarm.
  • Freeze sensors are particularly great for vacation homes, vacant properties, and other places that don't enjoy 24/7 supervision. Stick one in the basement, set up a Smart Alert, and avoid a really terrible watery surprise when you come back in the spring.
  • If you have multiple Freeze Sensors, your Dashboard will show you the average temperature reading for all of your sensors. In order to get individual readings, click on the tab for your Alarm Settings page.


freeze sensor

Even though it's named after just the low end, a freeze sensor is basically a temperature sensor. There are many ways to gauge temperature, and different technologies use different methods depending on the range within which they're required to work, whether or not they need to be waterproof, fragility, and size. Many residential-grade freeze sensors, including the SimpliSafe Freeze Sensor, use what's called a negative temperature coefficient (NTC) thermistor.

"Thermal" means temperature-related, and a "resistor" is something that impedes an electrical current. "Thermal" + "resistor" = "thermistor" — a gadget that determines temperature based on resistance to a current. NTC thermistors are made out of temperature-sensitive, semiconductive materials, such as metallic oxides or ceramics. These materials are "sintered" — fused together — into a chip.

Depending on the materials used, the sintering temperature, and the time it takes to fuse them, this chip will have a particular resistance profile — allowing a certain amount of electrical current through at high temperatures, and less and less as temperatures get colder. (This works on an atomic level because higher temperatures provide the energy necessary to activate more "charge carriers" — particles that can transfer electric current from a negatively charged pole to a positively charged pole). If you send a fixed amount of electrical current through the thermistor chip, and measure the voltage on the other side, you can figure out the temperature based on how much resistance the chip provided.

frozen faucet

SimpliSafe Freeze Sensors are made up of an NTC thermistor, a battery-powered electrode, an ammeter (to measure current), and a mechanism that does the necessary calculations in order to take in all this data and come out with a temperature reading. They are made for indoor use only — so those who need outdoor water fixture alarms, irrigation system alarms, or frost alarms should look into other options.


SimpliSafe uses NTC thermistors because they are very precise and operate well even at low temperatures — important for a freeze sensor! Because they're reliable and low-cost, many industries rely on NTC sensors to measure temperature. They're popular among food handling and processing professionals, as well as manufacturers of toaster ovens, hair dryers, refrigerators, and air conditioners. They're also very common in cars — a check engine light could be the result of an NTC thermistor at work!

Have any Freeze Sensor tips for your fellow customers? Share in the comments!

SimpliSafe blogger extrodaniare Cara Giaimo

Cara Giaimo

A man's home is his castle, as they say, and no matter what kind of castle you have, I'm here to help you fortify it. When I'm not blogging, you can usually find me running, jamming with friends, or making strange types of ice cream.

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