Beyond break-ins
When people think about a security system, they usually think of intruders. Yet many of the losses that owners face come from other causes: a burst pipe, a failed heater, a leaking water heater, a fire or a gas problem. Environmental sensors are the devices that watch for these hazards. They are called “non-intrusion” sensors because they have nothing to do with someone entering the building. They measure conditions in the space.
The same panel, hub or app that handles door and window sensors can often handle environmental sensors as well, so you get alerts in one place. Whether yours supports them depends on the system, so check before you buy.
The main types
Temperature sensors
These report the temperature of a room, and often send an alert if it rises or drops beyond limits you set. A low-temperature alert helps in vacant properties where heating could fail, and a high-temperature alert can be useful for server closets, wine storage, or a room with equipment that could overheat. Freeze sensors are a specialized version that triggers at a low threshold; they have their own article.
Humidity sensors
Humidity sensors measure moisture in the air. Persistently high humidity can encourage mold and may damage wood, paper, instruments or stored goods. Some people use these in basements, bathrooms, archives and storerooms. They give a trend rather than a warning of sudden disaster, and the readings are only a clue. Fixing a humidity problem usually involves ventilation, dehumidification or finding a source of moisture, which may need a professional.
Flood and water leak sensors
A flood sensor is typically a small unit with two contact points or a probe. When water bridges the contacts, it sends an alert. Place them where water would show up first: beside the water heater, under sinks, behind washing machines and dishwashers, near the sump pump, in basements, and below air-conditioning drip pans. Some models come with a cable that detects water along its length. These devices warn of water on the floor; they do not stop water unless paired with an automatic shutoff valve, which is a separate product. Reducing the harm from leaks is a broader subject, which is covered further under water damage.
Carbon monoxide detectors
Carbon monoxide (CO) is a gas that has no smell or color and can be dangerous. It is produced when fuel burns incompletely, for example in a faulty furnace, a blocked flue or a car left running in an attached garage. A CO detector senses the gas and sounds an alarm. It is a life-safety device, and codes about where it must be placed vary by location. Follow the manufacturer’s directions and local rules, and consult a licensed professional for questions about fuel-burning appliances. The household habits around carbon monoxide are worth learning separately. CO detection is different from smoke detection, so a smoke alarm does not protect you from it.
Smoke and heat
Fire detection is usually treated as its own category, with its own rules, and standalone devices differ from monitored ones. It is covered in a separate article on the role of fire detection, and the comparison of smoke alarms and heat detectors explains the sensing methods.
What the alerts can tell you
Environmental alerts are useful because they say something specific happened. A leak sensor says water has reached a spot. A temperature sensor says a room is colder than your limit. They cannot say why, or how bad it is. For example, a freeze alert does not tell you whether a pipe has burst, and a leak alert could mean a small drip or a major break. The alert is a prompt for someone to check.
Several details determine whether the alert is useful:
- Who receives it. A notification to a phone you do not check, or to a person who is away, wastes the sensor.
- How it is sent. Wi-Fi only devices go quiet when the router loses power. Cellular backup and battery backup improve the odds that a message gets through, though neither is a guarantee.
- Whether a human acts. Some professionally monitored systems pass along certain environmental or life-safety alerts to a monitoring center, while others send only a phone notification. This is an item to ask about in the monitoring contract, because it is easy to assume more than is actually offered.
Choosing and placing sensors
Start with risks specific to the building. A basement with a sump pump, an upstairs laundry room, a cabin with no heating in winter, and a shop with a refrigerated stockroom all have different priorities. A simple risk assessment is a good way to rank them. Then:
- Pick the hazards with the highest chance and the worst consequences.
- Match each with an appropriate sensor type and location.
- Decide on notification routes and a response plan.
- Think about power: batteries in wireless sensors need replacing, and low-battery warnings should not be ignored.
- Test after installation and regularly afterwards.
Sensors in damp or cold places may have temperature or moisture ratings. Read them, and avoid putting an indoor-rated sensor outdoors.
Limits to keep in mind
Environmental sensors detect only what is near them. A flood sensor in the wrong corner will miss a leak elsewhere. Sensors can fail, run out of battery or lose connection, and false alerts occur from condensation, spills or ordinary changes. No sensor guarantees you will avoid damage, and insurance coverage depends on your policy rather than the device. For fire, gas and electrical concerns, codes and licensing vary by place, so consult a licensed professional and your local authority.
Adding a few well-placed environmental sensors is often inexpensive compared with the cost of the damage they are meant to flag early. Treat them as early-warning tools, and plan what you will do when one goes off.