Air Exchangers and SIPs

Reducing leaks in a structure is central to achieving maximum energy performance. Many building strategies such as house wraps, vapor retarders, rigid insulation sheathing, tapes, and sealants are designed to reduce leakage. To provide low leakage and overall building energy efficiency, many choose to build with Structural Insulated Panels (SIPs), an insulated building system used in both residential and commercial construction.

Moisture, fumes from adhesives, smoking, and other gases and particulants can become trapped within the structure. When these pollutants accumulate to high levels they could potentially contribute to an unhealthy living environment.

Air exchangers allow a structure to remain efficient while also providing fresh comfort at a low operating cost. Indoor pollutants are continuously being taken away and replaced with fresh air. This provides a healthier living environment while retaining energy savings.

What Is An Air Exchanger?

This is a unit that can continually exchange stale inside air for fresh outside air, while also using the heat (or cold) from the exhaust air to raise or lower the temperature of the incoming air. A large percentage of the heat in the exhausted air can be recaptured. This efficiency allows a constant flow of fresh air, but doesn’t require a separate heating unit to heat all the incoming.

What Installation is Required?

Air exchangers require some planning before construction. The main unit should be placed in a temperature controlled area, basement, mechanical room, etc. Ductwork is typically run from rooms such as bathrooms, laundries, and kitchens to the air exchanger. These areas are chosen for their typically high levels of odor and humidity. Insulated ductwork is then run from the exchanger to the exterior of the building. A separate system of fresh air ductwork is run from the exterior of the building to the unit and continued to the fresh air drop, often a return air of a furnace.

How Do They Work?

Stale air is drawn from the bath, laundry, and kitchen to the air exchanger, and is ducted through the air exchanger to the outdoors. Meanwhile, fresh outside air is drawn to the air exchanger, then ducted to the inside fresh air drop point. As the two separate streams pass each other within the heat exchanger, they are separated by a medium that provides a conductor for the heat to be exchanged from the hot to the cold air. The incoming fresh air is warmed by the transfer of heat from the inside air and is then ducted into the living area or furnace air supply.

Excessive moisture can also be controlled with an air exchanger. As the airstreams pass the medium, condensate will appear on the exhaust side of the medium. The condensate forms because the warm moisture-laden exhaust air cannot hold as much moisture after its heat has been drawn through the medium. The excess moisture is removed and drained away.

How Can They Benefit The Sunbelt?

In areas where warm, outside humidity exists, an air exchanger will allow fresh air to be introduced to the building while controlling the humidity level. The two airstreams will follow the same routes as before, but as they pass within the unit, heat is drawn from the warm, humid outside air. Its ability to hold moisture decreases as it cools. Condensate is left behind as before, except that the condensate forms on the opposite side of the medium. Thus, the fresh incoming air is cooled and dried before being introduced into the living area. The air exchanger must be equipped with a desiccant system for sunbelt areas. Hvac near me

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