After thinking about the safety of the water heater based CO2 system for years, I finally built the deluxe (IMO) system.
The test room is an 8x8x8' room with 4Kw of HPS lighting. The whole system is controlled by one Siemens LOGO 12/24RC programmable relay (wannabe PLC).
The CO2 meter is a Honeywell (made by Sensaire) with a 0-10v output which is connected to the LOGO. When the CO2 falls below 1200 a diverter (valve) sends the exhaust (flue gas) from the heater into the grow room -when 1500 is reached, it sends the gas outside. If the temp rises above 82f the co2 turns off & if the temp goes to 86f, half of the lights turn off for a minimum 12 minutes -@ 92 all lights turn off & the system must be reset because there is a problem. I have a Kidde CO alarm with a display and piezo alarm that is hardwired to the LOGO controller so if the CO gets too high the CO2 is diverted outside and the system must be manually reset before the co2 will turn back on.
The CO2 portion of this system has been online for over a week and we have never had a CO alarm. The only reason the CO would ever get to a dangerous level is if there was a problem with the heater or possibly the CO2 controller. The diverter valve is spring loaded so if it doesn't get it's power, it sends the CO2 outside. When the H20 heater is running, it takes about 60 seconds to reach 1500ppm, if not it doesn't run more than 30 minutes. There is not much that could go wrong -no more than a commercial CO2 gen getting stuck on all day.
THe 40K BTU water heater puts makes 4.6 pounds of CO2 & .0016 pounds of CO per hour if it were running continuously for an entire 24 hour period (which it never does). While that small amount of CO could potentially poison the air in the grow room , it would take days of continuous running to even come close to making the building's environment hazardous.
BUT if you are thinking about using a gas heater for CO2, think again! Unless you are talking about a huge commercial space with some serious safeguards in place (redundant safety system, like an airplane!) it would be too dangerous. - The H2O heater might run 10 minutes out of an hour, the gas heater can run for hours at a time and the potential for serious, loss of life type danger is always present! I would not suggest using the heating system unless you really do your homework and have appropriate safeguards in place.
I don't care if you are using a commercial CO2 burner (none of which are UL listed) or the water heater setup, a CO alarm is an absolute neccessity! Not just an alarm but hooked up to kill the CO2 and/or a ventilation fan to blow the air out of the room. Smoke & fire alarms are also a must-have in any grow room where any HID lighting or CO2 burners are running. Just remember, all of the alarms in the world will do no good if they are not loud enough to wake you up in the middle of the night. -Another great thing is the Flame Defender auto-fire extinguishers. @ less than $50 for the 2Kg unit, it's the cheapest insurance you can possibly buy.
I'll post more info about this system after it has a few more miles. Diagrams, parts list, software... BTW, If you are thinking this system must have cost a fortune: LOGo controller $168; add-on module $80; CO2 controller $225; CO alarm $35; valve & diverter motor $80 (FeeBay); plus the relays & panel that was already installed...
1000000 BTU natural gas byproducts:
- Pounds per Million Btu of Energy Input
Carbon Dioxide 117#
Carbon Monoxide .0016#
Nitrogen Oxides .00368#
Sulfer Dioxide .00004#
A properly adjusted flame outputs very little CO -Mostly CO2 & water vapor.
Use your head!
DX -DX Hydro
