Reznor model RHH is the new pre-engineered air handler with 91% efficiency. Model RHH is available in four sizes, 130MBH, 180MBH, 260MBH and 350MBH, and can be used with either natural gas or propane. Model RHH units are approved for makeup air and space heating applications in commercial/industrial installations in the United States and Canada by ETL Testing Agency.