REFRIGERANT SWITCH: A Greenheck DGX-P116 Makeup Air Unit. Greenheck Fan Corp. has begun offering direct gas-fired makeup air units with the lower-GWP refrigerant R-454B. (Courtesy of Greenheck Fan ...

with an analytics firm recently saying more than 200 gas-fired units are in development across the U.S. That record natural gas production comes as gas-fired power plants are being used regularly to ...