Concealed Heat Pumps

Heat pump technology has improved significantly in recent years and is becoming a popular solution for new heating and cooling systems. The nature of a heat pump system allows flexibility in locating both indoor and outdoor equipment. The key to heat pump technology is the flow of outdoor air across a coil; in the summer, the system dumps heat into the outdoor air, and in the winter, the system extracts heat from the outdoor air. As an engineer, I never mind seeing equipment that makes a building run, but many owners and architects are concerned about the eyesore of exterior mechanical equipment. The outdoor units of a heat pump system are often located on a concrete pad at ground level, a flat roof, or wall mounted to the exterior of the building. But what happens when the site is cramped, the roof is sloped, and ruining the look of an exterior wall is not an option?

We have encountered this scenario more than once and have been challenged to find a creative solution for hiding our outdoor units. One of the approaches was to locate our units in a basement space modified to be outside of the building envelope and open to a free flow of outdoor air. There are a couple of critical points in this approach. First, this area of the basement is not conditioned and should be treated as if it were outside. This means there should be an insulated wall and floor separating the rest of the building. Second, providing sufficient outdoor airflow is essential to proper system operation. Without enough outdoor airflow, two things will happen: when cooling, the system will keep trying to dump heat into the air in the room, creating very hot conditions and losing efficiency; when heating, the system will try and extract heat from the already cold winter air creating very cold air, losing efficiency, and introducing the risk of equipment freezing. Depending on the design, basement wells with thru-wall fans may be needed to ensure adequate air movement. In a perfect world, there would always be an ideal spot for our systems, and we would never have to use this approach. But sometimes, these creative engineering solutions can help architects and owners save space and keep buildings beautiful!