Cleaning blades and lubricating shutter hinge points will extend the life of your fans.
Photo: Karen E. Varga

Editor’s note: The following article is excerpted from our 2015 Structural Strategies Guide. To read Bartok’s maintenance tips for other types of greenhouse structure components, visit bit.ly/29VSUv4

Keep it cool: fans and shutters

Fan systems have a depreciated life of about 5 years but can give longer service if properly maintained.

1. Clean the fan blades, motor and shutter. Check the fan belt for wear. Adjust the belt to achieve ½ inch to ¾ inch deflection in the center between the pulleys.

2. Lubricate the shutter hinge points so that they close tight. A 48-inch shutter that fails to close properly leaving 1-inch gaps allows about 23,000 Btus/hr of heat to escape.

3. Clean evaporative cooling pads and tanks. Replace deteriorated pads.

4. Service horizontal air flow (HAF) fans by cleaning the blades and guards. Oil bearings if they are not sealed.

Seal in the heat: vents and louvers

These allow considerable heat to escape during the winter if they do not close tight.

5. Roof and sidewall vents get considerable use and need to be adjusted so that they close even and tight. This involves lubricating bearings, rack and pinions, vent arm hinge points and checking fluid in gearbox drives. In houses with vents that don’t close tight, adding weather stripping may be the only way to stop excess infiltration.

6. Maximum and minimum vent position limit switches should be checked to see that they will stop vent travel at the correct position.

7. On roll up sidewalls, adding a permanent polycarbonate closure panel between the two end hoops on each corner of the hoophouse will provide a better heat seal. The plastic should be permanently sealed during the winter with wire lock or a furring strip.

Save energy: controls

Significant energy savings can be obtained by installing more accurate thermostats or electronic controllers.

8. Check the accuracy of all thermostats and sensors by using an ice bath or an accurate laboratory thermometer. Clean the sensor coil with compressed air. Check that all wire connections are tight and not broken.

9. Check the electric supply for low voltage to prevent damage to motors.

10. Run a test mode on the temperature alarm system to see that it is operating properly.

11. Test run the back-up generator and check its fuel supply.

John is an agricultural engineer, an emeritus extension professor at the University of Connecticut and a regular contributor to Greenhouse Management. He is an author, consultant and certified technical service provider doing greenhouse energy audits for USDA grant programs in New England. jbartok@rcn.com