SCHOFIELD, Wisconsin — Direct gas-fired makeup air units from Greenheck Fan Corp. now use R-454B, an A2L refrigerant with a low GWP that complies with mandates from the U.S. Environmental Protection Agency (EPA).

Because R-454B has mild flammability potential, the units underwent third-party testing from Intertek for all relevant product safety standards, including UL 60335-2-40. The tests certified that the refrigerant leak-detection and -mitigation systems are operating at full effectiveness, according to a press release from Greenheck.

Greenheck’s Model DGX units, which provide 100% outdoor air, also feature packaged direct expansion (PDX) cooling, housing all cooling components in one compact rooftop unit. Their improved design also includes microchannel coils, which have parallel flow tubes with tiny channels that carry refrigerant. Compared to standard coils, microchannel coils are on average 40% smaller, use 50% less refrigerant, and transfer heat 40% more efficiently, Greenheck said.