Solar Heat Recovery

Heat Recovery for “Once-through” Systems

Some buildings, such as hospitals, facilities requiring clean rooms and laboratories have rooms zoned as “one pass air” or “100% outside air ” systems. In these buildings, the HVAC system heats or cools the building’s air and passes it through the room then exhausts it after one pass. American Solar’s low-cost solar roofing and siding systems offer new cost efficiency for these “once-through” systems.

Our solar roofing and siding systems can recover solar heat from these surfaces to preheat (or pre-cool) the ventilation air coming into the building. The HVAC system can then use this “recovered solar heat” as another source to precondition the outside air coming into the building. The solar heat, even at low temperatures, reduces the expensive heating by the conventional heating systems.

Heat Recovery from “existing walls and roofs”

Another source of recoverable heat is the solar heat available from many ‘existing walls and roofs’. Our systems can recover this heat to preheat boiler intake air, heat occupied spaces, heat boiler makeup water, and for other uses. These systems produce the solar heat at the lowest cost because the “solar collector” (the wall or roof) is already in place. Only a small cost of installing the fans and ducts is required to produce large amounts of solar heat.

We can install heat exchangers in a range of applications to use that solar heat. For example, solar air to air heat exchangers can use solar heated air that contains odors, dust, or other undesirable traits and exchange the solar heat to fresh outside air. The fresh air is then used for space heating or other uses.

We can use solar heated air to heat the outdoor heat exchanger of a heat pump. This technique uses low-cost, low-temperature solar heat to boost the performance of a heat pump, which would otherwise use colder outside air. The solar air never enters the building, but the low-temperature solar heat can double the performance of the heat pump, producing more heat for less electrical use.

We can use solar air to liquid heating for processes like dyeing operations, which preheat cold water for hot dye tanks. Many other liquid heating processes use hot deionized water, which starts at city water or well water temperatures. Solar air to water heat exchangers preheat the water without the risk of contamination often found with water to water heat exchangers.