Installing an ERV in a Two-Family Passive House

Placetailor project manager Travis Anderson uses Siga tape to sel an outdoor air intake line for the Air Pohoda energy recovery ventilator at the Roxbury, Mass., “Supply House” job. Placetailor crafted a mix-and-match hybrid system for this project: The ERV unit shown is supplied by Air Pohoda, but the air intake and exhaust lines are an insulated expanded polystyrene (EPS) product supplied by Zehnder. Placetailor preferred the Zehnder ducting in this application because of its insulation qualities and its resistance to crushing in the dense-blown cellulose-insulated wall cavity.

Travis Anderson places a distribution manifold manufactured by Zehnder on top of the Air Pohoda ERV unit. The designers combined components from Zehnder and Air Pohoda for this installation.

Another look at the Zehnder air manifold that Placetailor coupled with an Air Pohoda ERV for the Roxbury project. The advantage designers saw with this distribution manifold was its sound control qualities. Looking inside the box, you can see the dark-colored mass-loaded vinyl core components, which tend to muffle and baffle mechanical sounds and the whistling or roaring of air movement. This is the supply manifold for the system.

This metal manifold, supplied by Air Pohoda, will serve as the return manifold for the Placetailor-design ERV system at the Roxbury “Supply House” project. The manifold lacks any sound attenuation characteristics, but the designers considered it adequate for the return lines of the system. However, the designers chose a Zehnder manifold with sound-attenuating mass-loaded vinyl core elements for the supply side of the air distribution system.

Carpenter Diego Gutierrez runs air supply hoses from Air Pohoda in the ceiling system of the Supply House two-family building. Note the metal suspended-ceiling grid, which is designed for sound-proofing. The metal framework, suspended from the main floor system with wires and used to support the drywall ceiling, will help decouple the downstairs living space from the space upstairs, which is part of the building’s other unit. (The second story of the building is split between two apartments, one of which occupies the entire first floor while the other occupies the entire third floor.)

Carpenter Diego Gutierrez and project manager Travis Anderson install air supply tubing in the ceiling of a room. This photograph shows two supply registers with tubing already attached.

In this split image, Diego Gutierrez and Travis Anderson work together to run tubing from supply registers back to the Air Pohoda ERV core and air handler. At the air handler, Anderson labels each line to identify the location it serves at the other end. This aids in balancing the system when the house is commissioned.

An air supply register in the ceiling. Each register can be served by either one or two three-inch lines, depending on the quantity of air needed. The system is fine-tuned by adjusting manifolds and fan speeds, and can be modulated as needed in service to respond to changes in the required exhaust and supply rates. The Air Pohoda system also offers active humidity control for the building.

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