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How Home Alarm System Sensors Work and How to Replace Them

Oct 31, 2022|

Keeping your family safe and secure from break-ins, fires, and natural disasters is probably one of your biggest priorities. The good news is that with the availability of home alarm systems, gaining the peace of mind that your family is protected has never been easier.

Installing a home security system can help keep your family and home safe in case of intruders, a fire, a carbon monoxide leak, and even flooding. If you’re considering investing in a home alarm system, you might be wondering how home alarm system sensors work and what it takes to maintain the sensors so the alert system doesn’t malfunction.

The purpose of this guide is to give you the information you need to understand home alarm system sensors and how they work, how they provide security for your home and loved ones, and the basics of what you need to know to maintain home alarm system sensors.

Vivint window sensor.

How do home alarm system sensors work?

Home alarm systems use a series of sensors that communicate what’s happening in a particular area of your home. When a sensor is triggered, it sends a signal over radio frequencies or wires to a central hub like the Vivint Smart Hub—which is generally a small box or touch screen located in an easy-to-access area of your home. Often, this hub is mounted on a wall or placed on a countertop.

Once the hub receives the signal from a triggered sensor, it sounds an audible alarm while also notifying the homeowner (which is you) through text, phone call, or a Wi-Fi-enabled alert on a mobile app.

If you’ve opted for professional monitoring, the hub will also send an immediate notification to the outside agency through a telephone line or cell connection, and they’ll try to contact or send help if they can’t get a hold of you. They’ll also confirm that it’s not a false alarm.

Let’s be neighbors.

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How do alarm system sensors provide security for your home?

Alarm system sensors—to provide the most protection for your family and home—are typically installed in strategic places where they’re most likely to detect an intruder or another type of problem by sensing motion, sound, or the opening of doors and windows.

Here’s how they keep you and your home secure.

Be alerted to unexpected movement

Motion sensors are used to detect unexpected movement in the home. These devices use either ultrasonic sound waves or infrared sensors to detect a potential intruder’s movement.

With ultrasonic sound wave technology, ultrasonic sensors shoot ultrasonic sound waves at objects around your home to detect active motion. Infrared sensors, on the other hand, use passive infrared technology to sense body heat. Both types of sensors are effective at sounding the alarm when an uninvited person enters the area.

Typically, motion sensors, like those offered by Vivint, are installed in high places in a home’s common rooms or hallways. This makes it easier to catch an intruder as they move through the house.

Know if a window breaks

Glass break sensors, like the Vivint Glass Break Sensor, pick up the sound of broken glass—a sound made if an intruder bursts through a window or glass door. The broken glass sound triggers the audible alarm and the chain of events that includes notification to the system’s hub, your smartphone, and even law enforcement if you have professional monitoring.

Because roaming animals could potentially set off a false alarm, many homeowners with pets choose to install a glass break detector over a motion detector to avoid the security sensors being triggered.

Monitor doors and windows

Contact sensors—also called door sensors, window sensors, or magnetic sensors—can tell if a door or window is being opened. When the alarm system isn’t activated, the sensor will often produce a chime to let the residents know when a door is opened. When the burglar alarm function is activated, opening the door will set off a door alarm.

Contact sensors are small battery-operated devices consisting of a sensor and a magnet. The sensor and magnet are placed on the parts of the door or window that meet. When the door or window opens, the contact is broken, causing a signal to be sent to the hub.

It’s important that your door and window sensors fit properly, which is why Vivint offers two types of sensors: a surface-mounted sensor that goes on the outside of the door or window and a recessed door sensor designed to be installed on the inside of the door.

Vivint window sensor.

How to replace a door or window sensor battery

From time to time, you might need to replace your door and window alarm sensor batteries. We give you step-by-step instructions on how to do this.

What you will need

First, you’ll need to find a small coin and purchase the battery that’s right for your particular type of sensor. You can look at the instructions that came with your system.

For Vivint’s Door and Window Sensor (DW11), for example, you’ll need a CR2032 battery, which is available at most hardware or superstores.

1. Disarm your system

Before you start working on the sensor, you need to disarm the system. You can do this from the system hub or—for systems that connect to smartphones—directly from your phone.

If you have a Vivint smart home system, for example, you can disarm the system directly from the Vivint app.

2. Remove the sensor from the backplate

You need to remove the sensor from its backplate. This is where your small coin comes in. Gently place the coin in the crevice between the sensor and the backplate and pry the two sides apart.

3. Replace the battery

Next, take the coin and slide it into the battery compartment. You won’t have to push it very far in. With just a gentle tap, the old battery should easily slide out of the sensor. Then, insert the new battery—positive side up—into the sensor.

4. Reattach the sensor

Once the new battery has been secured in the sensor, you can reattach the sensor to the backplate attached to the door or window. You do this by lining up the notches and securing the sensor in place. Then, open and close the door or window, so the sensor’s status is updated on the control panel/hub and your mobile app.

How to replace home alarm sensors

Most professional home alarm system manufacturers don’t recommend that homeowners replace their own home alarm sensors.

Not only can the system end up disabled following a DIY attempt — which could leave your home unprotected — but you might also end up damaging the system and voiding the warranty. The best course of action if you need to replace your home alarm system sensors is to contact a professional.

Vivint, for example, offers professional installation, and our experts can not only replace the sensors but also suggest the best places to put them, so your home is most protected.

Vivint window sensor.

Discover the leading home security system solutions from Vivint

Vivint is your one-stop solution for all your home security alarm system needs. You can build your home security system to include as many or as few devices as you want.

Whether you’re looking to install motion sensor alarms, fire alarms, smoke detectors, smart lights, security cameras, or any combination of Vivint’s wide range of home security solutions, we make it easy to design the system that’s right for you.

Find out more about how a Vivint smart home security system can be tailored for your specific needs. Give us a call at 855.822.1220 today.

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*Offer Details

Qualifying system purchase requires minimum $599.99 expenditure on equipment after all discounts have been applied, professional installation, and execution of Vivint monitoring services agreement. Click here for monthly service plan prices. DIY system purchases and reactivations of previously-installed systems not eligible for offer. Offer not available in all states or provinces. Equipment purchase may be financed separately subject to an agreement with one of Vivint's third-party financing partners. Monthly $1.48 cellular network maintenance fee applies. Taxes and local permit fees may apply.

Third-Party Financing Options Available

Financing eligibility and terms subject to credit approval by one of Vivint's third-party financing partners. Qualified customers may finance equipment purchase at 0% APR for up to 60 months. Month-to-month service agreement available when equipment is purchased upfront.

Vivint Systems & Services

System supports up to six cameras subject to sufficient WiFi speeds. Without a Vivint services plan, product and system functionality is limited (including loss of remote connectivity). Speak to a Vivint representative at the phone number in this offer for complete equipment, services, and package details, including pricing and financing details. Products and services in Louisiana provided by Vivint Louisiana Commercial Certificate #58280. See Vivint license numbers here.