Exhaust Fan Maintenance
Are your exhaust fans pulling enough air? Exhaust fans are the first step in keeping your greenhouse cool and if equipped can also help remove excess humidity. Fans require some maintenance but generally are very robust. During a normal day, they’ll kick on and off a lot depending on the temperature inside your space.
If you have several fans they are staged to kick on in degree increments by your greenhouse controller. When a greenhouse cools the first step of the system is to open the pad wall allowing cool air in. If that is sufficient the wall may close or even open in stages, 25%, 50% 100%. To continue to cool the greenhouse fan 1 kicks on at 70° Fans 2 & 3 at 73°, and all fans at 74°. At 75° the pump for the pad wall kicks in cooling the greenhouse like a swap cooler. (Temps here are for figurative purposes only, consult the Ball Red Book for best settings)
Alternatively, some greenhouses are cooled “long ways”, with a pad on the short wall, and two fans across the length. These fans also kick in on stages and occasionally have a high and low-speed settings controlled by the system.
Obviously, exhaust fans are one of the most important components of your greenhouse. Maintaining them properly is very important. Most are belt driven, these belts are under immense workload. They often are stretched, cracked by the relentless sun, and overworked. Inspecting and replacing them often is good practice. Sizes vary based on pully design, but if you remove one it generally has a part number you can reorder with.
It's important you practice the utmost safety when replacing belts. The fans are powerful, and will not hesitate to take off a finger, grab a tie, or your hair. Lock-out and tag-out procedures should be in place when working with this type of equipment.
We're often asked where to grease certain connections, we usually advise against grease. Grease can often build up soil particles, dirt, gunk, etc. leaving parts worse off. Best practice, if it has a grease fitting use it, otherwise keep it dry and clean.
We can do exhaust maintenance for you, we carry belts and often can have you back to full cool in no time. As usual, let us know If you have any comments questions, or concerns!
-Georg