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Charley's Greenhouse
17979 State Route 536
Mt. Vernon, WA 98273
1-800-322-4707
Fax 360-873-8264

Call Center Direct Line
360-428-2626

Retail Store Direct Line
360-395-3001

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Heat Calculation Formulas

Heat conservation is first. Seal and insulate where needed.
  • Heat only as much as your plants require (this may feel cool to you).
  • Reduce heat loss by using a Heat-Saver Fan to pull heat off the ceiling.
  • Our Prewired Portable Heater Thermostat will also save heat by accurately turning your 120 volt heater on and off.


How To Calculate Heat Requirements

The following formula can be used to determine the approximate heating requirements of your greenhouse: A X D X 1.1 = Btu’s. “A” is the total wall and roof surface area of your greenhouse. “D” is the difference between coldest outdoor winter temperature and the night temperature desired in your greenhouse. "Btu’s" is the heat requirement. Subtract 30% if greenhouse is insulated using double glazing or polyethylene liner. Subtract another 30% if it is a lean-to greenhouse on heated wall.