Saturday, September 20, 2008

Greenhouse - Reducing Heating Costs II

This is the second in a series on reducing heating costs in greenhouses. This post focuses on increasing the efficiency of heating systems.

Efficient Heating Systems
  • Installation of floor or under-bench heat will allow air temperature to be set 5º - 10ºF lower.
  • Yearly maintenance - Check boiler, burner and backup systems to make sure they are operating at peak efficiency. Have furnaces cleaned and adjusted and an efficiency test run before heating season. A 2% increase in efficiency for a 30' x 150' greenhouse will save about 200 gallons of fuel oil or equivalent in propane.
  • Clean heating pipes and other radiation surfaces frequently.
  • Check accuracy of thermostats - correcting a reading that is 2ºF high will save $100-$200.
  • Install electronic thermostats or controllers with a 1 ° F accuracy. Potential yearly savings of 500 gallons of fuel oil or equivalent in propane in a 30' x 100' greenhouse when changing from a mechanical to electronic thermostat or controller.
  • Aspirate thermostats or sensors for more uniform temperature control. Differential between on and off can be reduced as much as 6ºF.
  • Install horizontal air flow (HAF) fans to get more uniform temperature in the growing area.
  • Insulate distribution pipes in areas where heat is not required.
  • Check and repair leaks in valves, steam traps and pipes.

Reprinted from "Greenhouse Energy Conservation Checklist" by John W. Bartok, Jr., Agricultural Engineer, Natural Resources Mgt. & Engr. Dept., University of Connecticut , Storrs CT

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