A screw-drive system is quieter than chain-drive (and thus pricier), and has considerably more power to move the lifting mechanism along the threaded steel rod. Other advantages: fewer moving parts, and reduced maintenance.
Belt-drive systems are the most expensive. Because they use rubber belts to operate the door, they are also quietest.
Plenty of power: To lift the typical garage door, the opener's motor should be at least one-half horsepower. For a smoother, quieter operation, look for one that lifts and lowers the door without bucking, which can wear down the motor too quickly. If the opener jumps to a start, the motor might not be powerful enough for the weight of the door. If you get a larger motor than needed, some experts say, the opener will last longer.
Speed limit: With power comes speed. Though more expensive openers get the garage open faster, they tend to close more slowly, reducing the chance of an accident.
Alight safely: All but the cheapest openers come with lights built into the box that holds the motor. When the opener is activated, the light comes on, and in some cases stays on as long the door is open; in others, it will shut off after a few minutes. The idea is to give you enough time to get out of the garage without tripping over something.
Stop short: What if your toddler decides to run under the door while it's opening or closing? Federal law requires that automatic openers come to an immediate stop, then head in the reverse direction, to prevent an accident. On most models, an electronic beam remains focused on the door during operation - if a child breaks the beam, the mechanism reacts.
Safe, but secure? Manufacturers say that every time the door is lifted, a new, random code is generated for the opener. This deters burglars, and also means that your garage door won't open when the neighbor clicks his remote.
Control issues: Door openers are typically activated by either a remote controller or a hard-wired push button mounted inside the door of the garage or somewhere between your house and the garage. Remotes require frequent battery-level checks, so you don't get caught without power as you arrive home in a downpour. Some openers also have keypads that let you create a security code to enter the garage without the remote control.
What will it cost? Chain-drive openers start at $100, screw-drives run about $175, and belt-drives go for $200.
To DIY or not: Installing an automatic opener is not all that difficult, but if it requires additional wiring, you should contact a licensed electrician to make the necessary changes. The thing to get right is locating the mechanism so that the door opens and shuts easily - often easier said than done.
Caveat emptor: Check the warranty of the unit you buy, because it could be voided or compromised if you don't have the opener professionally installed. Also, check the repair and replacement provisions of the warranty. Garage openers are often temperamental, and a lot of frustrated homeowners go without rather than spend the money to fix them.
Want Alan J. Heavens' advice on a home-improvement project or purchase? E-mail him at email@example.com or write to him at The Inquirer, Box 8263, Philadelphia 19101.