Extension spring systems should always be restrained by a safety cable that runs through the middle of the spring, tying off to a solid point at the rear and front of the horizontal door track. Extension springs represent a hazard to bystanders when a spring, pulley, or cable breaks under tension. Metal parts from extension spring systems can suddenly be launched.
However, in addition to potentially causing injuries to the under-prepared DIYer, a malfunctioning door can become a safety hazard to you and your family. Keep in mind, according to the National Electronic Injury Surveillance System (NEISS), over 13000 people checked into hospitals with garage related injuries in the United States in 2007. You don’t want to turn a loved one into a statistic just to save a few dollars!
The third stage of garage door opener technology uses a frequency spectrum range between 300-400 MHz and rolling code (code hopping) technology to defeat code grabbers. In addition to transmitting a unique identifier for the remote control, a sequence number and an encrypted message are also sent. Although an intruder could still capture the code used to open a garage door, the sequence number immediately expires, so retransmitting the code later would not open the garage door. The encryption makes it extremely difficult for an intruder to forge a message with the next sequence number that would open the door. Some rolling code systems are more involved than others. Because there is a high probability that someone will push the remote's button while not in range and thus advance the sequence number, the receiver does not insist the sequence number increase by exactly one; it will accept a sequence number that falls within a narrow window or two successive sequence numbers in a much wider window. Rolling code technology is also used on car remote controls and with some internet protocols for secure sites.
With garage door installation costs, these numbers also include the actual purchase of the new door and other hardware, including the tracks, adhesives, connectors and fasteners. Keep in mind that if these numbers seem extreme, garage door replacement and upgrades can yield, on average, one of the highest returns on investments for homeowners — with an expected 85 percent.