HVAC Frequently Asked Questions

Q: In a sealed environment, how many BTUs of cooling do I need per 1000 watt light?  How many tons?

A: 4000 BTUs of cooling per 1000 watt.  There are 12,000 BTU’s per ton of cooling, allowing 3 lights per ton.

Q: How do I properly size my dehumidifier?
A: The amount needed for dehumidification is generally equal to the amount of water your plants drink daily.  Plants drinking 4 liters every 3 days will need 1.3 liters of dehumidification per plant per day.

Q: What should my CO2 levels be at?
A: CO2 levels can boost growth rates by up to 30% at 1500 ppm.  Anything above 1500 ppm is wasted.

Q: When air cooling my lights, how much CFM do I need?
A: An accepted amount of movement is 250 CFM per 1000 watt fixture.

Q: For exchanging air in my room, how much CFM do I need to account for?
A: Calculate your rooms cubic feet (LxWxH) and divide that number by 3 (the amount of minutes the air should be exchange in) and that is the required CFM.

Q: How much CFM is lost through my carbon filter?
A: It depends on the fan and filter combination in use. Typically, a CANFAN and filter at the maximum exhaust CFM rating will have approximately 0.7” wg pressure drop, which accounts for 20% of air flow.  MAXFAN will lose 7-15%.  Cheaper fans can lose upwards of 40%-60% through a carbon filter.