An underfloor ducted heat pump uses the same technology as a standard ducted system, but the air handler sits beneath the house in a subfloor space rather than in the ceiling cavity. Supply vents are set into the floor instead of the ceiling, and the return air grille is usually built into a wall, often in a hallway.Underfloor installations suit homes with limited roof space or where ceiling access is difficult. The subfloor environment brings its own conditions, including moisture and ventilation, that affect the system differently to a ceiling installation.Maintenance requirements are largely the same as a ceiling-mounted ducted system, though access for servicing happens from underneath the house rather than through the roof.