Greenhouse Heating Systems, Greenhouse Solar Heaters and Solar Greenhouses
With 4-5 hours of sunlight on average per day your Growing Dome® Kit with the 5-wall polycarbonate glazing panels will typically stay 30 degrees Farenheit above the outside temperature over night. What this means is that on very cold nights (below zero) and/or after a series of cloudy cold days you may need to supplement with some form of additional heat. There are a number of options for heating your Growing Dome including some net-zero options. All of these heating options are do-it-yourself options as we don’t offer any of these for sale. We’ll start with the most conventional here and go to the more eco-friendly options:
1. PROPANE HEATER: We do not sell propane heaters, but list some recommendations below. Placing the heater next to the above ground pond is a good idea because this heats the water. Then the water radiates the heat throughout the Growing Dome over time.
Mr. Heater– This heater has a low, medium or high setting (8,000, 12,000, 14,000 BTU). It is a little round heater that mounts to the top of a propane tank. This heater is adequate for up to and including a 26′ Growing Dome (View single burner heater on Mr. Heater’s website). For larger sizes, you can get a second head for the tank for twice the heat output (View two burner heater on Mr. Heater’s website). This heater does not have a thermostat, so the downside is the amount of propane used continuously and the inconvenience of having to turn it off and on.
Southern Burner – The “Rolls Royce” of greenhouse heaters, this heater is specifically designed for greenhouses and impervious to rust in humid conditions. They are 25,000 BTU which is too big for an 18′ and almost too big for a 22′ Growing Dome, but will work in a 22′ due to the built in thermostat. This heater is ideal for a 33′ diameter Growing Dome. You would need two heaters for a 42′ or a 51′.
There are two types of Southern Heaters – vented and non-vented. Both types require an air intake pipe run to the outside. If you are growing sensitive plants such as orchids, you will want to go with the vented heater and install the chimney with chimney jack. For general greenhouse heating, we recommend the non-vented Southern Burner. The non-vented distributes carbon dioxide into the Growing Dome which the plants like. 405-224-5000 http://www.southernburner.com
2. FLOATING POND HEATER: This is an electric heater that floats on the surface of the water tank. It must be plugged in to the grid and is very power hungry, so we don’t recommend this option for that reason. It is more efficient, although, than an electric space heater because the water stores and releases the heat more efficiently than the air in the greenhouse.
3. WOODBURNING STOVE: This would be a custom installation of the owner’s choice and it is up to the owner to make sure that the stovepipe and placement of the stove don’t pose a fire hazard to the structure or others near it. It may be necessary to check with your local building department before installing the stove.
4. CLOSED LOOP SOLAR WATER HEATER with ANTIFREEZE: A food-grade antifreeze called “propylene glycol” is heated in the panels pictured here and then pumped thru a copper coil placed in the water tank. The anitfreeze is moved by a circulating pump which is solar powered. The pressure of the system does need to be regulated, so we recommend consulting with and/or hiring an expert (a plumber or solar contractor) to help you get this system operating properly. This method has proven incredibly successful in augmenting solar gain by raising the temperature of the water tank significantly. The warmer water then releases more heat into the Growing Dome at night.
Currently there is no “out of the box” solution for this system and it will need to be custom built. You have a couple of options for moving forward with this as a heating option. Be ready for a fair amount of research regardless of which route you choose.
- Most solar system contractors also install solar hot water heater systems. We suggest getting in touch with a local solar system contractor to see if they would be available to custom build a solar hot water system for your Growing Dome. You are welcome to have them contact us for guidance on what works best.
- You can do-it-yourself by either purchasing the solar collector, tubing, pump and other components yourself and assembling them or you can build the solar collector panel yourself. There are a lot of instructions online about how to build your own solar collector. This option obviously is more cost effective, but, depending on your level of experience with plumbing and woodworking, can be time consuming and challenging.
5. FLOATING ROW COVERS AND CLOCHES: Neither of these are heaters, but rather an added layer of frost protection to keep your plants from freezing when/if the Growing Dome dips below 30 degrees F. Many owners avoid heating altogether by using these methods instead. You can buy Agribon brand floating row cover from a company such as GrowOrganic.com. Watch our video to learn more about cloches.
6. OTHER OPTIONS: Other folks have been very creative and added systems such as geothermal heaters, climate batteries, and in-floor radiant heating. If you have a system you’re designing for your Growing Dome and are interested in knowing our experience with such a system, we’d be delighted to talk with you further. Just give us a call at 800-753-9333, give us the name on your customer file and we’ll put you in touch with our technical department.