Any recommendations for CO2 burners?

Indoor at higher altitude. Hoping to also increase temps a little during overnight. Winter is getting colder. Thanks.

I run autopilot 4 burner suppose be one better co2 machines don't know how big your space is but they have an 8 burner to.

The Titan 2 burner LP does the trick for me for 4'x14' canopy of flowering girls.