VCG CO2 generators VCG-6 (1) burner operating VCG-6 (2) burners operating VCG-27 (2) burners operating VCG-27 (5) burners operating VCG-27 (7) burners operating VCG-27 (10) burners operating  
  Electronic ignition (no open pilot flames) Yes Yes Yes Yes Yes Yes  
  Dual redundant electrical solenoid valves Yes Yes Yes Yes Yes Yes  
  Tip-over switch (shuts unit off if tipped over) Yes Yes Yes Yes Yes Yes  
  Variable CO2 output Yes Yes Yes Yes Yes Yes  
  Comes in either Propane or Natural Gas models Yes Yes Yes Yes Yes Yes  
  Recommended for 128 cubic foot space or less Yes Yes OK OK OK OK  
  Recommended for 128 - 384 cubic foot space No Yes Yes OK OK OK  
  Recommended for 384 - 960 cubic foot space No No No Yes OK OK  
  Recommended for 960 - 1792 cubic foot space No No No No Yes OK  
  Recommended for 1792 - 3200 cubic foot space No No No No No Yes  
  3-year warranty Yes Yes Yes Yes Yes Yes  
                 
* To calculate the growing area's cubic feet, multiply the width x length x height of the area.  
* Both the VCG-6 and VCG-27 can operate (2) burners. Since the VCG-27 has (10) burners as compared to the VCG-6 which has only (2) burners, if expansion is planned, choose the VCG-27. Remember that each burner produces about 3000 BTU of heat. Make sure you account for the extra heat while planning the cooling requirements for the growing area. Running more burners will increase CO2 levels faster, but will also heat the growing area faster. Use only as many burners as necesary to raise the CO2 level to the desired level in 10 minutes.