We have all heard that there is no such thing as a “free lunch”; Well, the process outlined in this article may be as close to one as possible. Most of us already know the benefits of CO2 enrichment for photosynthesis. To maximize indoor growth and greenhouse potential, CO2 is supplemented to maintain an approximate level of 1500 ppm, this may require frequent trips to an industrial gas supplier and / or heavy use of propane or natural gas, and costs related. It is ironic that many indoor farmers are expelling CO2 outside of household heaters and water heaters at the same time that they release or generate CO2 for an indoor grow room or greenhouse.
Propane and natural gas burn clean enough that small non-vented gas appliances have been approved for indoor use. All of these gas combustion devices use oxygen (in air) to burn the gas, resulting in the by-products of CO2, H20 (moisture), and heat (Reusch). The exhaust from gas appliances can provide 3 essential conditions to maximize growth: humidity, temperature and CO2 level. Most of the exhaust heat is removed by the furnace or water heater heat exchanger; resulting in a slightly hot exhaust. Photosynthesis of many plants, including marijuana, in a CO2-enriched environment is most efficient around 85 degrees F.
If the exhaust from a large gas heater is diverted into the growing area, there is great potential for all oxygen to be burned or displaced, as well as CO (carbon monoxide build-up), resulting in conditions of toxic air. With the right equipment, the CO2 from your gas furnace and / or the exhaust from the water heater can be safely used to supplement the CO2 used in your grow room. This will save time and money, make plants grow well, reduce fuel use, and dramatically reduce the amount of greenhouse gases released into the environment. With this technique, you will help prevent global warming while optimizing growing conditions. The key to doing this safely and effectively is to divert enough exhaust from your gas appliance to your grow area to maintain a CO2 level of 1500 ppm and have additional exhaust directed outside.
“The Occupational Safety and Health Administration (OSHA) and the American Conference of Governmental Industrial Hygienists (ACGIH) have established workplace safety standards of 5,000 ppm” and very high levels of CO2 can cause undetectable suffocation when O2 in blood is replaced by CO2 (Minnesota Department of Health). Keep a CO (carbon monoxide) detector in the grow room for added safety in case equipment malfunctions! Do not attempt this project if you use hot oil or kerosene, which do not burn cleanly!
The trick to harnessing this unused CO2 source from gas furnaces and water heaters is power buffers. A power damper is a section of conduit with a hatch that opens and closes flow through the conduit and is powered by electricity. Some dampers close with applied current and others are designed to open. Most buffers are low voltage, so the correct size transformer must be connected in-line to the snubber; there are some 110 volt shock absorbers. Quality shocks will seal much better than cheap shocks. This simple addition to a CO2 enrichment system will pay for itself many times over (especially at current fuel prices) and reduce home or business emissions to the environment, making your project more “green”. It is necessary to have a CO2 level monitor connected to a controller (sequencer) to indicate to the buffers (applying energy) when CO2 is needed and when the threshold has been reached. You can still use your controller to run your CO2 generator and / or your regulator.
Find the exhaust pipe from your gas furnace or water heater. These devices should already be properly ventilated. Turn off your gas appliance while working on this. Disconnect (or cut) a section of conduit where you will be closest, with the fewest bends, to hit and route a new conduit to the grow area. The few necessary items can be found in most heating supply stores. If you can’t find dampers that match the size and type of duct you have, you may need to convert the duct to a size or type that you can find dampers for. With a “Y” connector and a power regulator that closes when power is added, connect in line with conduit to the outside. For smooth flow, install “Y” so exhaust reaches ‘bottom’ of ‘Y’ duct section. Now take the damper that opens when power is applied, connect it to the other “Y” opening. Run a duct from this ‘power opening’ regulator into the grow area above the plants, as CO2 is heavier than air; but you probably already know. Now all you have to do is connect the dampers or use a multi-outlet adapter and connect them to your CO2 sequencer along with your CO2 generator or CO2 tank regulator using a 3-outlet adapter.
If the pipes are away from the exterior wall or ceiling, there may be duct booster fans in line. If the grow room is not flowing through the new duct, an in-line duct booster fan may be needed, especially if there is one used in the original duct that goes outside beyond the new “Y” section. “of the appliance. If you add a duct booster fan, wire it or plug it in together with the dampers, they will turn on and off together. Many ovens will have a suitable exhaust fan, so an additional duct booster fan will not be necessary. Be on the lookout for booster fans (if any) in the original duct between the “Y” junction and the outside, there is a possibility that they will overheat if they run when the outside damper is closed.
Once this is set up, when your CO2 sequencer determines that it is time to add CO2 to the room and turn on the power, the outside exhaust damper will close and the grow room damper will open; resulting in exhaust from the furnace or hot water heater being diverted into the grow room. The CO2 generator or release regulator will work as well, this ensures that the room will always have just the right amount of CO2, even if the furnace or water heater is not in use. When the proper level is reached and the sequencer shuts down, the hatch leading to the grow room will close and the hatch to the chute leading to the outside will reopen. All exhaust gases at this point will be vented outside until the room needs more CO2.
For safety, make sure that all circuits and / or outlets are not supplying more than 80% of their rated watt load and that they are wired correctly. Also, be sure to secure the conduit well. 200 ° F rated duct tape holds up better than regular duct tape (for connecting sections of duct).
If you are diverting the water heater exhaust for this CO2 enrichment supplement, you can take further advantage of this setting by scheduling showers, dishes, and laundry, as the lights come on (time the enrichment equipment runs longest). ) and during the light cycle. in general.
With this system, farmers will find that they take fewer trips to fill propane or CO2 tanks and spend less money, while levels in the grow room remain the same.
This addition to an enrichment system will also reduce the volume of CO2 released into the environment from the home or business. The CO2 diverted to the room is used by plants during photosynthesis, further reducing the release of CO2 from the gas appliance into the environment. With this system, the room will reach the desired CO2 level faster and fluctuate less, further enhancing growth.
List of works cited:
Minnesota Department of Health
This page, located on the Minnesota Department of Health website, is a good source for showing the adverse health effects that high C02 levels will cause. The best I can say is that this site is run by the state government. The information on this page is consistent with other sources that also describe the harmful health effects caused by too much CO2 in the air. This page, while short, clearly presents the figures and dangers, agreed upon by a government scientist, that are associated with high levels of CO2. The statement, “At very high levels, 30,000 ppm and above, CO2 can cause suffocation as it replaces oxygen in our blood.” clearly demonstrates the potentially fatal condition that elevated CO2 levels can cause.
“Carbon Dioxide (CO2)” Minnesota Department of Health. March 2004.
June 27, 2005 http://www.health.state.mn.us/divs/eh/indoorair/co2/>
Reusch, William. “Reaction of Alkanes” Michigan State University
This page clearly describes the physical process of propane combustion. After reviewing a dozen sources of propane and natural gas combustion, I found that this page has more accurate, detailed, yet understandable descriptions of the possible reactions of propane combustion. Although the article does not cite references for the information it contains, the information is consistent with common knowledge and other reference materials and is located on the Michigan State University Department of Chemistry website. By showing the structural formulas for the above reactions along with clear reasoning showing why the reactions may differ, this source will allow the reader of my essay to understand what products can be created by burning propane. This article shows how CO2 and H2O are the direct products obtained by burning propane when sufficient O2 is present.
Reusch, William. “Reactions of Alkanes” Michigan State University
Chemistry Department 1999. rev. 2004. June 28, 2005
http://www.cem.msu.edu/~reusch/VirtualText/funcrx1.htm>