Construction
Garage Door Opener Sizing
Most door issues blamed on a 'weak opener' are actually broken springs — the opener doesn't lift the door, the springs do. That said, here's what HP / Nm you need so the motor isn't undersized for your setup.
FAQ
What's the 'lift by one hand' test? +
A properly balanced garage door, springs intact, should lift with one hand. The opener exists to overcome friction and provide controlled motion — not to drag a heavy door up. If you can't lift it by hand, get the springs fixed first.
1/2 HP vs 3/4 HP vs 1.25 HP? +
For a balanced single door under 200 lb, 1/2 HP is plenty. Double doors over 300 lb or 8'+ tall doors need 3/4 HP minimum. 1.25 HP is for solid wood doors over 500 lb or commercial cycles.
HPc vs HP — what's the difference? +
"HPc" (horsepower comparable) is what Chamberlain/LiftMaster use because their DC motors don't quote pure horsepower. A "3/4 HPc" DC motor produces equivalent torque to a 3/4 HP AC motor.
Jackshaft openers — when? +
When you have no headroom (cathedral ceiling garage), need a wall-mount, or want the fastest open speed. LiftMaster 8500W is the residential standard. Pricey but premium.
Belt vs chain noise difference? +
Chain is loud — fine for detached garages. Belt drives are 70-80% quieter, essential if there's living space above the garage. DC direct-drive is quietest of all but priciest.