In last month’s column, I touched on air-to-water heat pumps because they are rapidly becoming very saleable to consumers. In some areas of the U.S., electric heating, cooling and production of DHW are no longer an option and fossil fuels have been outlawed.

One thing not well understood is the need for us to design our heating systems to utilize the lowest possible water temperature on a design day (either the coldest or hottest day typically seen each heating and cooling season0. If you don’t yet have a good heat loss/gain program, you will definitely need one for designing HVAC systems. I use several, but my favorite is Elite Software RHVAC, which utilizes ACCA’s Manual J for its foundation. It is accepted by all AHJs (authorities having jurisdiction) and stands up in courts of law for testimony I have given before jury trials.