Between work meetings with clients, I found time to read the entire 59 page Installation Manual for the geothermal heat pump we are planning to use in the River House. This particular model from Water Furnace features a variable speed compressor, variable speed, fan, and variable speed circulation pump. What this means is that the entire system can operate at the exact rate to provide the heating or cooling needs of the house at any given time. Most systems have one or two speeds and maintain temperature by cycling on and off. In addition to the significant energy savings, this variable speed capability leads to very consistent temperatures, quieter operation, and lower air speed coming out of the vents.