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DIY Natural Gas co2 Generator

Discussion in 'Do It Yourself' started by tat2ue, Aug 9, 2009.


    tat2ue Well-Known Member

    I have been wanting to add co2 to my grow room since I finished it a cpl months ago but the cash outlay kept me from doing it. Then I ran across an artical on the web titled "CO2 for FREE" written by David Oppenheimer (Great read). Simply put, he explained how you can use the exhaust gas from a natural gas hot water heater to enrich your growing area with co2 for a mere fraction of the cost of a tank system or one of those pricey co2 generators made by "CAP" or "BluOx". Since my water heater is about 10' from my grow room this worked out great for me. All I did was place a "T" in the exhaust line exiting the top of the heater. I then ran a 4" metal duct (not that flimsey 4" dryer duct) into my grow room. Once inside my grow room I continued it to a bathroom exhaust fan ($14.00 at Loews) I built into a box and attached to the wall. You can use a 4" inline booster fan but I would have had to order it online from Loews or HD .The exit side is a 3" duct fitting that I attached a 90 degree elbow to and directed the flow of exhaust gas (CO2) behind a 16" oscilating fan that I mounted close to the ceiling. The fan disperses the co2 over my entire grow area for complete co2 saturation.

    Before I installed my "Ghetto Generator" my co2 ppm in my sealed grow room ranged from 400 - 500 ppm. After the instalation it measured 3000 ppm:shock: WAAAAY to high. And since I don't have one of those co2 monitors like a CAP1/2 or 3 I had to dial my Ghetto Generator"in with a $17.00 timer. After trial and error I got it to keep a constant 1500 -1900 ppm with lights on by setting my timer at 15 min on and 30 min off. I also installed a Carbon Monoxide alarm to be on the safe side....Total cost was around $80.00 and install time ran 3-4 hours.

    I run 4 x 1000w HPS lights in cool tubes vented into the attic w/ an 800cfm inline fan drawing from outside air and the temps stay in the range of 82 to 85 degrees while venting the warm air from the water heater into the room. I do have a line from my central air running into the 8 x 12 grow room to help keep it cool also. Well anyway I hope this helps a few of yall out. Here are a few more specs on my grow-op.

    Room Size is 8 x 12

    Set up two ebb & flow tables that are 3 x 8, one on each side of the room. Each table has eighty 3" netpots for a total of 160 plant sites (I lollypop all my plants and they go straight from the DIY aero cloner into flower)

    Ea table is covered by 2 x 1000w HPS cool tubes

    Ph range is 5.8 to 6.0

    Nute ppm range is kept close to 1500ppm at all times

    Night time temps (lights off) is 69 to 71 degrees

    Day temps w/ co2 and lights on ranges from 82 to 86 degrees.

    CO2 ranges (lights on) 1500 to 1900 ppm (and is now FREEEEEEE:grin:)

    Thats All Folks ...Hope this helps someone cause it sure saved me a bundle of $$$$$$

    Attached Files:


    darkdestruction420 Well-Known Member

    why not make some beer or wine? or just mix sugar yeast and water? that messing with natural gas heater stuff sounds dangerous.

    darkdestruction420 Well-Known Member

    sorry, i didnt read your post thourougly enough. you would need to make alot of beer or wine to work in your situation. i didnt realize your room was so big, must of rushed through that part reading..

    BigBudBalls Well-Known Member

    Have you measured the CO ppm???

    tat2ue Well-Known Member

    I have not taken a reading as of this writing on the ppm for the carbon monoxide. For now I have a carbon monoxide audible alarm setup near the exhaust vent blower. The room is vented once every 2 hours for 15 minuits.

    For the most part, the fan that pulls the co2 into the room is doing so mostly from the pilot light in the water heater which burns a steady BLUE flame which means mostly co2 and very little co. The pppm on both the co2 and co spike when the water heater is heating up the tank like when someone is takeing a shower or the little womans runs the dishwasher and levels back out when the room runs thru a venting cycle.

    I just took a shower and went in and took a ppm reading on the co2 and it spiked at 2500ppm but the co alarm was quiet which means carbon Monoxide ppm are at an acceptable level.

    To be on the safe side, if I plan on being in the room for more an extended period of time, I run a manual vent cycle for about 10 min prior to be safe.
    That 5hit likes this.
    That 5hit

    That 5hit Well-Known Member

    i love this idea not for everone but it for me

    BigBudBalls Well-Known Member

    It it a MAJOR code violation.
    That 5hit likes this.
    That 5hit

    That 5hit Well-Known Member

    thats a joke right
    reading that and then looking at your avatar ialmost died

    but you r playing right
    stop it
    stop it now

    BigBudBalls Well-Known Member

    So putting exhaust gases back into a living area isn't a code violation? Where do you live? Nigeria?

    (I guess I am a dummy, and thought a chimney was to let the gases *out* of the living areas. Silly me, I guess the chimneys aren't needed.)

    tat2ue Well-Known Member

    BBB..Exhaust gases are mainly the CO2 gases expelled from my natural gas hot water heaters pilot light and an occasional heating of the water tank The gases are drawn into a sealed 8 x 12 flower room built in my garage. Not the living area of the house. I know it is not code, but neither is a MJ grow room in ones home. I know it sounds like a disaster waiting to happen but I don't see any difference between my DIY set up and a high $$$$$$ store bought natural gas gen like Bluox,GreenAir, or CAP ect. I do take precautions and monitor CO2 and Monoxide levels constantly. Mr. Balls , you have my utmost respect for your concern as for the safety issues that one would encounter in this DIY project.:clap::clap:
    That 5hit likes this.

    BigBudBalls Well-Known Member

    I was going after the code violation, not the safety of it. You had said previously that you have a CO alarm and a CO2 meter, so its monitored.
    But its still a violation.
    (and indoor CO2 levels over 1000ppm are considered by OSHA to be a problem. Granted OSHA doesn't involve itself with small companies nor homes)

    born2killspam Well-Known Member

    There are some flukey risks that go along with it, ergo the code violations, but if you're monitoring CO.... I'd double check that the active draw doesn't stand a chance of altering the burn, or flaking out the pilot light though..
    Oh, and if you ever have an hvac/furnace guy come for any reason and he sees that, he'll know immediately what you're up to.. Most of those guys have gone to jobs to undo stupid jimmy-rigs done up by pot growers..:)

    nikk Active Member

    you read that ladies and gentlemen....and thats why they call him the GOD FATHER

    just teasing born....thats a scene from one of my favorite movies

    born2killspam Well-Known Member

    I've honestly never watched those movies.. Well I think I've passed out while they've been playing, I was just never in the mood to dedicate 3-4 hrs attention to anything..
    I've never really watched Star Wars either..
    I'm just worried that this could potentially allow gusting back to the heater/furnace or something.. Probably wouldn't considering that every NG HWH I've ever seen has an open concept reducer above it going to the exhaust ducts, but I'd want to double check with an HVAC guy, and prevent other HVAC guys from seeing this..

    nikk Active Member

    the movie is called OLD SCHOOL,its a comedy,funny stuff...and yeah i definitely see you point tho,you know what i noticed,that you are one of the few people on here that really takes other people's safety into consideration,youre so passionate about that,most people would just say things like "hell yeah,thats fucking awesome set up bro" follow suit and kill themselves if it wasnt for people like you putting things into perspective...kudos to you my man

    born2killspam Well-Known Member

    Oh I saw that, but all I remember is Blue.. I thought the line was from the Godfather..
    And I really couldn't care if stupid ppl hurt themselves (naive/uninformed ppl are slightly different).. Thing is when that kind of accident goes down, the media & police team up to cast an evil shadow over this entire hobby.. Like I said, theres no better footage than wheeling body-bags and pot plants out of the same house..

    nikk Active Member

    BLUE YOU'RE MY BOY..lmao,one of the funniest movies ever,but yeah body bags and weed paraphernalia isnt a good look for none of us,especially when it all couldve been prevented with some common sense
    born2killspam likes this.

    fatfarmer34 Well-Known Member

    "Come on we are all streaking"........ Just my 2 cents, it looks like a pretty good idea as long as the safety considerations are observed. In my own set up I have a HVAC duct going into my room but it is not permanent I can take it down and put original pipe back in place if I have to have someone in the basement. I think a backdraft damper would be a good idea to stop airflow going back towards water heater exhaust duct.

    unclejuicee Member

    I personally think this is a great idea. AS lONG as the air is monitored. Why not optimize on this gas. AWESOME!

    Bluediemond Active Member

    To clear up a couple myths.....or to show who knows how little they are talking about....here's a good start.

    A natural gas flame produces CO2. Water heater....Gas Dryer....Gas stove....anything that burns propane or natural gas.

    The problem comes when oxygen runs out, the flame starts to burn CO2 since there's not much left. Carbon Monoxide becomes the by-product from this point.

    A simple fix....allow fresh air in the area! The same requirements with the expensive CO2 Generators give this same warning.....you MUST have a fresh air source for the burner.

    The only 2 options are to supply the O2 requirement (a small fresh air stream to the heater/dryer/water heater or a big bottle of CO2 feeding the room.

    What's overlooked is the fact that a bottle of CO2 is JUST as deadly as an improperly supplied gas burner. CO2 will kill you just like carbon monoxide. They both work on burning all of the oxygen in the room...and once oxygen levels get too low, they both are just as deadly.

    IF you want a CO2 generator.....use a meter. Plain and simple. Neither is more dangerous, but both can be deadly.

    Both produce GREAT results but the CO2 bottles are considerably more expensive.

    CO2 bottles are considerably more expensive to refill as you will refill them often. Gas burners are far less expensive but generate more heat.

    Personally I use a gas burner, outside my house, with a network of tubing to cool it before it comes inside the room. Less heat and far cheaper.

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