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Fan Size Calculator Heater Size Calculator Plastic Size Calculator Surface Area Calculators
Not sure what size heater you need for your greenhouse kit? Our Greenhouse heater size calculator does all the work for you. Just enter in all of the greenhouse information below. Then you can choose from our extensive selection of greenhouse heaters and thermostat controls.
Greenhouse Heater Size Calculator
Surface Area of Greenhouse - This is the total square feet of exposed surface area (this is not length x width) your greenhouse has (don't include floor). To find out the surface area of a greenhouse we sell, click here. To find the surface area of a different greenhouse, click here to use our greenhouse area calculators.
Minimum Outside Temperature (°F) - You will want to enter the lowest temperature expected for your area. Not sure? Use the USDA Zone Map to find the minimum temperature for your area.
Inside Temperature (°F) - This is the minimum temperature you would want to maintain in your greenhouse when heating.
Heat Loss Value - Check the list below to find the heat loss value for the covering on your greenhouse. Some values may vary with manufacturer. If you know the R-value of your covering, you can convert it to a heat loss value using this formula: Heat loss value = 1 / R-value.
Area x (In - Out) x Heat Loss
Minimum BTUs Needed - This is the minimum amount of BTU output your greenhouse heater should have. If the heater only has a BTU input rating, use the following formula. BTU output = heater efficiency * BTU input. View Our Selection of Greenhouse Heaters

Greenhouse Covering Heat Loss Values
4 mil polyethylene
1.20
4 mm (5/32") twinwall polycarbonate
.70
6 mil polyethylene
1.15
6 mm (1/4") twinwall polycarbonate
.62
6 mil poly double layer (inflated)
.70
6mm polycarbonate roof & glass walls
.90
11 mil woven polyethylene
1.05
8 mm (5/16") twinwall polycarbonate
.58
3 mm (1/8") glass (single layer)
1.13
10mm (3/8") twinwall polycarbonate
.53
Double layer insulated glass
.45
10 mm (3/8") triple wall polycarbonate
.48
Polycarbonate / fiberglass (single layer)
1.20
16 mm (5/8") 5 wall polycarbonate
.33

Greenhouse Exposed Surface Area
Grow More Greenhouses
GM8 (8' x 11') 333 GM8ext (8' x 5') 104
GM10 (10' x 13') 442 GM10ext (10' x 6.5') 149
GM13 (13' x 13) 557 GM13ext (13' x 6.5') 175
GM16 (16' x 13') 681 GM16ext (16' x 6.5') 202
Sunshine Greenhouses
GKP64 - 6' x 4' 195 GKP88 - 8' x 8' 369
GKP68 - 6' x 8' 273 GKP812 - 8' x 12' 462
GKP612 - 6' x 12' 352 GKP816 - 8' x 16' 555
Cross Country Greenhouses
Because of the large number of sizes available, you will need to use our surface area calculator
to find the total surface area for the model you are interested in.
Modine Hot Dawg HD75 Gas Heaters modine, hot, dawg, hd, dog, gas, heater, hd75, garage, shop, unit, greenhouse, dang, HD75AS0111, HD75AS0121, 4010170, 4010160
Free Shipping
Price: $1,299.00

Modine Hot Dawg heaters are an affordable way to heat your garage, shop, greenhouse, or barn. Modine HD heaters feature direct spark ignition and low profile design. Each Hot Dawg heater includes: electronic ignition, power exhaust system, advanced diagnostic system for dependable worry-free operation, lots of safety features, high power fan to provide even heat distribution, rust-resistant aluminized steel exchanger, and a baked-on enamel finish made to protect the HD from harsh environments....

240v Electric Heater with 24v Controls greenhouse, heater, electric, portable, space, 220, 240, plug, in, hobby, garage, shop
Price: $289.00

Need help sizing a heater for your greenhouse? Use our Greenhouse Heater Size Calculator One of the most common problems when heating with a 240 volt electric heater is finding one that can be controlled with an external thermostat at a resonable price. Look no further. This kit includes a rugged and reliable 19,107 BTU heater and everything you need to automate it with a separate control of your choice. Works great for heating small to medium greenhouses and keeping large greenhouses above...

Sterling XF100 Gas Unit Heater sterling, xf100, tf100, heater, gas, propane, xf, tf, furnace, greenhouse, shop, natural, separated, combustion
Free Shipping
Price: $1,299.00

- Replaces Sterling TF100 and SF100 heaters - The Sterling XF series gas unit heaters replace the TF and SF series heaters and combine them into one unit that can be vented as standard open combustion (Exhaust pipe only) or separated combustion (Using both an exhaust and intake pipe). They are a great heating option for large greenhouses, warehouses, commercial structures, etc. Sterling XF heaters feature: tubular heat exchanger, power exhaust system, electronic ignition, advanced diagnostic...

King Pic-A-Watt 240v Electric Heater king, 240, 220, volt, electric, heater, greenhouse, space, garage, shop, small, portable, fan, room
Price: $659.00

Need help sizing a heater for your greenhouse? Use our Greenhouse Heater Size Calculator This rugged heater will provide your greenhouse, garage, or shop with years of reliable heating. The King heater has an amazing 19,454 BTU output at the 5700 watt setting. Everything about this heater is high quality including the accurate capillary thermostat (Range 40° F to 85° F), sealed and permanently lubricated fan motor, delayed fan which continues to run after heater cuts off to remove heat from...

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ACF Greenhouses
380 Greenhouse Drive
Buffalo Junction, Virginia 24529
1-888-888-9050 toll free

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