311 Motors for Greenhouse Vents
Replacements, repair, and the biggest in-house stock of 311 motors in North America. We ship across the US and Canada.
So What is a 311 Motor?
The 311 is one of those motors that’s been around forever. If you’ve got an older greenhouse, especially a Lord & Burnham or a Mark II, chances are you’ve got a 311 somewhere driving the roof vents, sidewall vents, or louvers. Heavy-duty thing, sealed up tight against moisture, and built to keep cycling open and closed every day without giving you trouble.
Greenhouses are rough on motors. Humidity, dust, temperature swings, plus the vents opening and closing a couple dozen times a day. Most regular motors don’t last long in that kind of environment. The 311 was built specifically for this work, so the gearing holds up and the housing doesn’t corrode out on you after a couple seasons.
Why Growers Stick With the 311
Built for the greenhouse
Sealed against moisture and dust. Standard motors don’t survive in there for long, the 311 does.
Steady torque
Smooth open and close. No sudden jerks that wear out your vent arms and brackets.
Drop-in replacement
Matches the original mounting and wiring on most setups, usually a straightforward swap.
Built to last
Heavy-duty gear train. It’ll handle years of daily cycling without falling apart on you.
Where You’ll Find Them
- Roof vent drives on Lord & Burnham, Mark II, and similar older greenhouses
- Sidewall louvers and ridge vent setups
- Curtain and shade systems
- Retrofit jobs replacing an old motor that finally gave up
The Specs (Quick Look)
| Type | Greenhouse vent actuator motor |
|---|---|
| Used for | Roof vents, sidewall vents, louver systems |
| Environment | Sealed for high humidity, dust, and temperature swings |
| Drive output | Steady torque, good for medium to heavy duty vent loads |
| Fit | Standard mounting, works with most greenhouse controllers |
| Service | We rebuild and repair 311s in-house |
Signs Your 311 is Done (Or Close to It)
- Vent isn’t opening or closing all the way, or it stops part way through
- Grinding, humming, clicking, basically any noise it didn’t make before
- Moisture inside, rust, or burn marks on the housing
- Keeps tripping the breaker or blowing the fuse on the vent circuit
- Vent arm looking bent or the linkage straining against the drive
Don’t ignore these. Running a failing motor usually damages the surrounding hardware too, you can turn a $200 motor job into a $1,500 vent arm and linkage job pretty fast. If you’re seeing any of that, get in touch and we’ll figure out what’s going on.
Frequently Asked Questions
Can I just repair my 311, or do I need a new one?
Depends on the shape it’s in. We look at the gearbox, brushes, and seals first. A lot of 311s come in looking dead and we can rebuild them. If it’s truly beyond saving, we’ll tell you and quote a replacement.
Do you actually keep 311 motors in stock?
Yep. We carry the biggest in-house stock of greenhouse vent parts in North America, including 311s. Most orders ship same week.
How long does a rebuild take?
Usually 5 to 10 business days from when we get the motor, depending on parts and what else is in the queue. We’ll tell you upfront when we look at it.
Will a 311 fit my Lord & Burnham or Mark II?
Most of the time yes. The 311 uses standard mounting and wiring. Send us a photo of what you’ve got now (motor, nameplate, vent linkage) and we’ll confirm before you ship it.
Do you ship to Canada?
Yes. We deal with Canadian customers all the time, both for parts and repairs.
Other Greenhouse Vent Motors We Work On
Need a 311? Let’s Talk.
Tell us about your greenhouse and what’s going on with the current setup. We’ll get back to you with stock, repair options, and a price.