Brooklyn Passive House Mechanicals

Here’s one of two 9,000-Btu/hr air handlers for the ducted mini-split system, mounted above the ceiling of an upstairs bathroom, directly under the smart vapor barrier that protects insulation in the building’s low-slope roof. Copper refrigerant lines, insulated with foam tubing, sprout from the side of the unit and bend toward the roof (they’ll be attached to the outdoor side of the split system when weather allows that part of the system to be placed). The white piping next to the refrigerant lines is the system’s condensate line (condensate will be pumped under pressure into the home’s plumbing drain system). To the right is a short return plenum that communicates with the home’s hallway.

Supply ductwork from a 9,000-Btu/hr air handler, one of two for the home, leads out of the unit and into roof and wall chases. The ducts will feed distant rooms in the house, enabling the system to mix air volumes in the building, equalize temperatures, and distribute passive solar heat and other internal gains in the building around the various occupied spaces. The galvanized ductwork is sealed with mastic for airtightness. Light-gauge steel framing for the bathroom ceiling will be covered with drywall soon.

The metal duct register shown here is one end of a pass-through vent set in the master bedroom to help move return air from the bedroom into the hallway, where the ducted mini-split system’s return grille is located. The other end of the pass-through vent is located in a hallway closet with a louvered door.

Corrugated plastic tubing for the energy recovery ventilator terminates in a ceiling register in the basement level of the house, covered for temporary protection with pink insulation foam. Ventilation airflows for the home are too slow and low-volume to supply heating or cooling air, or to create significant mixing of air. The larger ductwork of the mini-split heating and cooling system, with its more powerful air handler, provides those functions, while the heat recovery ventilator supplies tempered fresh air to each room and pulls humidity and odors out of the house through return grilles located in the bathrooms and kitchen.

White corrugated tubing for the energy recovery ventilation system in the ceiling of the Brooklyn brownstone. All bedrooms and living spaces in the house will receive air through supply ducts, while return ducts will withdraw air from bathrooms and the kitchen and exhaust it from the house. The body of the system will recover heat from the outgoing air and warm the incoming air in winter. Before the house is occupied, the ERV system should be commissioned by an expert who will make sure the incoming and outgoing airflows are balanced to allow the system to run at its full rated efficiency.

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