All Our Ducts in a Row

Ductwork on the second floor. Air enters through the hole in the floor and leaves through the rectangular duct.

Second-floor ductwork in progress. Air enters through the hole at right and leaves through the rectangular duct.

The plumbers have arrived. They’re also the HVAC system contractors – in fact, the company is called Chuck’s Heating and Air Conditioning – and we share the job site with them throughout this week. With a crew of eight, led by Chuck’s son Brad, they work lightning fast but they also take up a lot of the house. We stay out of each other’s way when possible: on a day Terry expected Brad’s crew to install ductwork on the first and second floors, we built walls in the basement. But when I can’t get to the chop saw table because a plumber is standing on it to cut a hole through the ceiling, or when I have to wait at the bottom of the stairs for traffic to clear, the place feels mighty crowded.

Full house. (And there's another truck parked around back!)

Full house. (And there’s ANOTHER truck parked around back!)

Congestion in the basement.

Congestion in the basement.

Our ductwork got crowded in a hurry, too. We’re using forced hot air for heating and cooling, and two huge air ducts run through the living-room hearth blockout. One is the insulated “out” duct, which blows hot or cold air up to each room. The other is the uninsulated “return” duct, which sucks each room’s ambient air back down to the basement fan and heat exchanger. Together, these ducts use up most of the space set aside for utilities in the blockout… leaving almost no room for the stove’s flue.

Ducts fill the blockout.

Ducts fill the blockout. The stove flue needs to fit in the next bay right of the one he’s working in.

This conflict looked bad. The flue needs to travel up through the second floor and escape out a gable end. With so many ducts in the way, the only remaining route for the flue appeared to go directly through a floor truss. As the resident structural engineer, I vehemently opposed cutting the truss – it exists to support our second floor, we NEED it! Terry felt the blockout walls could support the truss on either side (and thus become load-bearing walls), but everybody agreed this solution was not ideal. Somebody floated an idea to angle the flue into the living room high on the hearth wall, an eyesore for sure. Then I stumbled on a far better solution by taking a quick measurement. The gap between the truss and the 2×4 hearth wall is 7 inches; a small cutout in the wall’s top plate (which carries no load) will easily accommodate an 8-inch flue pipe. Hooray!

When we weren’t busy resolving utility conflicts, we actually got a lot of carpentry accomplished, too. Most impressively, we installed the walkout basement’s sliding door. The three-lite door assembly is nearly ten feet wide and very heavy, so we removed the middle lite (the slider itself) as soon as we could. Colin and I nailed plastic flanges around three edges of the frame to provide nailing surfaces, along with 1×12 lumber to create jamb extensions. Meanwhile, Terry sawed out an inch of foam along the side of the floor slab so the door’s bottom edge would also slide in.

We built our own jamb extensions using 1x12 lumber.

We built our own jamb extensions using 1×12 lumber.

The sliding door in place.

The sliding door in place, before adding Zip-Tape and trim.

The quest continues for an airtight house to meet Efficiency Vermont standards. Colin applied a bead of caulk around the sliding door frame before we lifted it into place, and he Zip-Taped around the perimeter after. This level of tightness demands a proper ventilation system built into the house, with a minimum number of air exchanges per minute, and I’m excited for Brad’s crew to deliver.

One thought on “All Our Ducts in a Row

  1. Pingback: Two Hundred Fifty | PERCH ENGINEERING PLC

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