Wide variety of types available. Selection will depend on what you want to accomplish. Some feel a loud alarm at the point of entry will scare away the intruder. Others prefer a remote alarm located in a bedroom that will alert only the homeowner. Others prefer an outside alarm that will alert neighbors. Other kinds will sound an alarm and are connected directly to monitoring systems that will alert the police.
Simple alarms may consist of a door-locking device with a buzzer attached. When the device is tampered with or the door opened, the alarm sounds.
Many intrusion alarms are more elaborate and have twocomponents. A perimeter alarm detects intrusion at points of entry, such as door and windows. An area alarm detects motion inside a room.
Uses either ultrasonic waves or microwaves to detect motion. When it detects motion, it triggers an alarm.
Generally plugs into a standard electrical outlet, so they’re easy to install.
Ultrasonic detector waves only go as far as the wall of the room, while microwaves penetrate walls and windows.
Some ultrasonic alarms use a narrow sonic beam that must be bounced off a hard surface. Here, the intruder must break the beam to be detected.
Other ultrasonic alarms use a wide beam that fills the room and detects motion anywhere in the trap zone.
The most important consideration with this type of alarm is avoiding false alarms. These can be caused by air conditioners or drapery moving above a hot air register. Better systems have built in circuitry that does not respond to these types of signals.
Some systems have extra repeater alarms or satellites. These can be plugged in anywhere in the home to add extra noise and relay the warning to remote rooms.
Detects radon, a colorless, odorless, radioactive gas formed wherever there is uranium, an element present throughout the crust of the earth. It poses little risk if it makes its way to open air, but if it seeps into a house, it can collect in hazardous concentrations.
This detector consists of a small sheet of plastic. Alpha particles that strike the plastic cause microscopic pockmarks.
After an exposure period, users mail the detector to a lab. The lab’s count of the pockmarks gives a direct measure of the mean radon concentration.
Another type uses activated-charcoal granules, which trap radon gas. After an exposure time, the container is resealed and shipped back to a lab for analysis.
Has a locking button on the inside knob but no key device on the outside knob.
Can be either a knob or a lever.
In an emergency, the lock can be opened from the outside by inserting a narrow object through the small hole in the outside knob and either depressing or turning the locking mechanism inside, depending on the type of lock.
Available in a wide variety of styles and finishes.
Called “dead” because there are no springs to operate the bolt. It is only operated manually with a key or a thumb turn from the inside.
The bolt locks the door to the frame and helps prevent someone from prying the door open.
The throw is the length the bolt is extended from the lock housing.The industry standard is a 1” throw.
Locks are designed to fit specific size holes and backsets. Backset refers to the distance between the edge of the door and the center of the handle.
A single-cylinder deadbolt is operated with a key from the outside and with a turn button on the inside. It is used mostly with solid metal or wood doors.
A double-cylinder deadbolt is operated with a key on both the inside and outside. It is best used on a door with glass in or around them as the style prevents someone from breaking the glass, reaching in and unlocking the door.
Double-cylinder deadbolts can pose a danger during an emergency. If the key is missing or not readily available, people could be trapped inside a locked house. In some areas, codes may not permit this style of deadbolt.