Why Your Bathroom Vent Turns On By Itself And Won't Stop Running
Whether you call it a bathroom vent or an exhaust fan, that small device high up on the wall or mounted in the ceiling has an important job to do, circulating the air to clear smells and remove moisture. Bathroom vents are activated in a variety of ways, but most switch themselves off after a while. If yours is turning on by itself and then just keeps on running, it's a sign there's a problem. It could be an electrical fault, it could be over-sensitivity, or it could be excess humidity. Let's take a closer look.
Before we talk abut how long your vent should stay on, it's important to understand that some modern homes have bathroom and kitchen fans that are actually supposed to run all day, every day. It's called decentralized Mechanical Extraction Ventilation (dMEV). As well as maintaining high air quality, it means switches are unnecessary.
Other bathroom vents switch on or off in a variety of ways. They could be manual, connected to the light switch, timed, motion-activated, or have a built-in humidity sensor. The more complex a device is, the more potential there is for something to go wrong. If you still have the original instructions, you can check out the troubleshooting section; many guides are also available online. However, tinkering with anything linked to power can be dangerous, so unless the fix is straightforward, this is probably one of those electrical jobs you shouldn't tackle yourself.
It's possible that high humidity is to blame, and it's important you fix it quickly
If the bathroom vent has a humidity sensor (humidistat), your problem might be something as simple as the device being set to the wrong level, and it may be possible to adjust it (again, check the manual or online). If you've made changes and still the vent won't stop running, the problem could be with the level of humidity in the bathroom itself.
Consistently high humidity provides a breeding ground for mold and mildew. This can be a serious health issue. Some people can experience severe reactions, including asthma attacks. You can test if there's mold in your house, but tracking down the underlying issue is important. It could be a leak in the plumbing, for example, and that's only going to get worse and more expensive unless it is repaired.
It's not unusual for some types of bathroom vents to turn on by themselves. If they keep on running beyond a half hour, you'll want to find the source of the problem quickly. Trouble with electrical or plumbing systems could impact your pocket, but mold and mildew can affect your health.