Horsepower Rating, Not What It Used to Be

Faced with buying a new garage door opener, one of the first things you’ll have to decide is whether you’ll get one with an AC or DC motor.

If you’re replacing an older model there’s a good chance that you’ll have one that uses alternating current (AC). New AC garage door openers are pretty rare nowadays, especially for residential openers.

DC motors have a number of advantages: they aren’t as bulky; they operate more smoothly; and they offer soft start and stop functionality, meaning they don’t have that jarring jerk when the door begins moving. DC motors don’t interfere with some wireless equipment that AC motors mess with. It’s also much simpler and cheaper to implement battery backup on a DC motor. Finally, they are much quieter.

Basically I’m saying that if you are buying something for the home, go for a DC motor in your garage door opener. Be sure to check if the opener you’re considering has a brushless motor. If not, then it won’t have a comparable lifespan to an AC motor of the same performance.

Horsing Around

AC motors can have their power measured in horsepower, and this has been the standard power rating unit for openers long before DC motors became the norm. DC motors, because of the way they develop power, aren’t measured in horsepower. This is a problem, since the horsepower rating of an opener is the main piece of information we use to decide if it will be strong enough to lift a given door.

Luckily most manufacturers have devised horsepower equivalent ratings. They often use a unit like “HPc” or something similar to denote this. This does not mean that the DC motor in question has the same absolute power as the AC horsepower equivalent, but that they perform in a similar fashion.

How Many Ponies?

You’ll encounter a fairly wide range of horsepower ratings when shopping for a garage door opener, starting with openers that have one-third of a horsepower. These are best avoided, as that really is too weak for even standard doors. It may actually lift the door, but having a motor constantly work at its operational limit will reduce its lifespan and the difference in price is really not worth the compromise.

At the moment, half-horsepower garage door openers are probably the most popular. These will generally lift a single-car door of up to 300 pounds. Some “heavy-duty” models may even go up to 350 pounds.

This should accommodate most standard single- and some double- width doors.

I recommend three-quarter horsepower openers as the sweet spot. These openers are usually rated for doors up to 550 pounds in weight.

These are the ones you’d want to use for non-sectional wooden doors, those with insulation, or doors wider than standard. Since the price difference between half- and three-quarter horsepower products are often negligible I’d go for them nine times out of ten.

Doors with one horsepower or more can lift the heaviest door. Very wide doors, doors made from heavy materials or of course provide maximum efficiency and longevity when paired with lighter doors.

My current best pick is a 1.25 horsepower unit and is basically (with a little luck) the last opener you’ll ever buy.

Pick a Card

I usually say that in the end your budget is the most influential deciding factor, but with the shrinking price difference among models based purely on horsepower, it pays to have a slightly overpowered door opener.

Save the extra $30 or $40 and go for the three-quarter horsepower model in the series you are considering. I think the additional peace of mind is worth that extra bit of scratch.

Remember that a garage door opener is usually a long-term purchase. If you pick a good one, it should keep trucking for more than a decade of normal use. Cheaping out may mean buying another one three to five years down the line. Suddenly, saving 50 bucks doesn’t make that much sense. More powerful motors are more likely to have lifetime warranties, which means that if the motor does give up the ghost ten years down the line, you can actually have it fixed under warranty.

I think you’ll agree that’s the most sensible route.