Heating Systems for Your DIY Greenhouse
After reading our posts on types and design considerations for building your DIY Greenhouse you most likely have a decent idea of what your greenhouse will look like and how you would like it to function. If this includes use during the colder months of the year, you will need to look into some form of heating system. Luckily you have a lot of choices to choose from.
In case you are wondering how large your heater needs to be, we also wrote a post on calculating the correct size heater for your DIY greenhouse.
Several heating methods and designs can be used in greenhouses, each varying in either their heating source or method for heating a room. Some may heat and circulate water; others may use heat and a fan to raise the temperature of the air directly. Regardless of what system you do decide to go with, the first thing to consider is always safety. Because heating systems can and are fuel fired, they will most likely require a building permit (check your local building code laws) and installation by a licensed contractor.
The heating source that you do decide upon can have a significant impact on your heating costs and bills. For fuel fired heating sources, natural gas is generally cheaper than other options, but you may decide on kerosene, propane or even electricity. Check pricing for each option in your area (should be listed in dollars per million BTU) when considering cost.
Electric heaters work by passing electric current through material with high resistance to electricity. As the current passes through the medium it generates heat due to the resistance the electrons encounter while traveling. Have you ever looked into a toaster and seen the red glowing strands of wire? Whether you’re heating a room or making toast for your breakfast plate, the theory is the same. Electric heaters are easy to install, readily available, and depending on the type – may not require expert installation. They are not very efficient however, and on average the cost of electricity per BTU for heating purposes is higher than other sources. Due to this fact, they are better suited for milder climates or in cases where short term heating is needed. If you do decide on an electric heater, be sure to get one that has an adjustable thermostat and automatic shut off in the event that it gets tipped over (to prevent against fires).
As the name implies, kerosene heaters use the fuel source of kerosene to create heat. Kerosene is a petroleum-based product, and like gasoline or diesel fuel it is created during fractional distillation from crude oil. It’s burn characteristics make a very suitable fuel source for heaters, cooking stoves and in some cases transportation. Small kerosene heaters can be purchased rather inexpensively and be capable of producing up to and around 35,000 BTU/hr. Kerosene does have it’s draw backs however. First the fumes from the heaters can be deadly if not properly vented (though there are several “vent free” heaters available these days it is best to still vent rooms heated with kerosene). Further these fumes may cause damage to your crops if allowed to accumulate over longer periods of time. Most of the kerosene heaters we have seen also do not have thermostats installed; so proper room temperature regulation may be an issue an owner would have to contend with. For these reasons we would recommend kerosene heaters only for short term or emergency heating needs.
Heating systems that use gas, whether propane or natural gas, are a common choice for DIY greenhouses. They offer more control and “set it and forget it” capability than other types of heating systems. If you use natural gas for your home you are most likely already familiar with how the systems work. Within the self contained heater unit there will be a constant flame call the “pilot light”. The gas heating system will be controlled via an adjustable thermostat, which will monitor the room’s temperature constantly. Should the temperature drop below a set point, the heater will automatically allow fuel to enter into the combustion chamber where it will be “lit” by the pilot light and cause heat. As heat is created it will be circulated into the room via a fan or fans. The waste products of combustion, harmful and toxic gases, will be vented to the outside of the building. Once the thermostat sees that the temperature of the room has reached it’s upper setting, the system will shut off, leaving only the pilot light lit for the next cycle. These systems are often the most efficient manner by which to heat a building, but do require more upfront expenses for installation.
Existing Heating Systems
If your plans call for an attached greenhouse, then extending the systems from your existing structure will most likely be the cheapest option. You will need to consult and hire a licensed professional, but the upkeep and process in general will not need to be painful. One thing you should consider is installing a thermostat that only controls the greenhouse room and is not tied to other rooms of your home or outbuilding. These are typically called “zones” and your contractor will know what you are talking about if you use that nomenclature. The only limiting factor to using an existing system will be the capacity of your installed system, and making sure it can properly handle the extra burden of the new room.
You might also explore solar heating methods.
As you can see there are many types of heating options available for your DIY greenhouse. Make sure you carefully consider all of your options and choices before selecting yours. If possible, speak with other gardeners who have their own greenhouse and get their feedback. Enjoy and good luck!