Greenhouse Heater Size Calculator
Size a greenhouse heater so your seedlings survive a cold night without overspending on wattage. Enter the length, width and average height of the greenhouse in feet to get its exposed surface area, then set the temperature you want to hold inside and the coldest outside temperature you expect. The calculator uses the heat loss formula, surface area times the temperature difference times a covering U factor, to estimate the BTU per hour the heater must supply. Single layer glass or film loses heat fast, while double wall polycarbonate holds it far better, so pick the U value that matches your covering. It converts the result to watts for electric heaters too. Everything is calculated instantly in your browser with no signup.
How to use Greenhouse Heater Size Calculator
- Enter the greenhouse dimensions to set its surface area.
- Enter your target inside temperature.
- Enter the coldest expected outside temperature.
- Read the required heater output in BTU per hour and watts.
Frequently asked questions
How does the calculator size a greenhouse heater?
It multiplies the greenhouse surface area, the temperature difference you want to hold, and a heat loss factor to get the required BTU per hour and watts.
Why does the inside minus outside temperature matter?
The bigger the gap between your target inside temperature and the coldest outside temperature, the more heat escapes, so a larger difference needs a bigger heater.
How do BTU and watts relate here?
The tool reports both because about 3.41 BTU per hour equals one watt, letting you match either an electric heater in watts or a gas one in BTU.
What is Greenhouse Heater Size Calculator?
Size a greenhouse heater so your seedlings survive a cold night without overspending on wattage. Enter the length, width and average height of the greenhouse in feet to get its exposed surface area, then set the temperature you want to hold inside and the coldest outside temperature you expect.
Is Greenhouse Heater Size Calculator free to use?
Yes. Greenhouse Heater Size Calculator is completely free, with no sign-up and no usage limits.
Does Greenhouse Heater Size Calculator work in a web browser?
Yes. Greenhouse Heater Size Calculator runs in any modern web browser. There is nothing to download or install.
Is my data private with Greenhouse Heater Size Calculator?
Yes. Greenhouse Heater Size Calculator runs entirely on your device in your browser, so nothing you enter is uploaded to a server.
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