An Experience with Mini Duct Installation

Converting a 1910 Shingle Style house with no air conditioning to one with a whole-house system was not something I took lightly. I have spent my life restoring old houses. If HVAC was in my future it had better be efficient and virtually invisible.

I chose a small-duct aspiration system from a reputable company, but knew that the success or failure of the experience would come down to the local contractor’s willingness to be flexible. In my house, almost all rooms were mini-duct accessible through hidden spaces. Even the laundry chute connecting the third floor to the cellar would be used for the coolant and condensate lines, so there was plenty of wiggle room.

plaster removed, lath exposure

Papered plaster, then wood lath, was surgically removed for the return duct.

I met with all three of the manufacturer-preferred contractors working in my area. The first took no measurements and made no load assessment. (The load assessment determines how many units and components are required to efficiently cool the area.) Not surprisingly, that contractor declined to make a bid. The second contractor made two site visits and performed a load assessment. After seven months, repeated calls, and a nudge from the manufacturer, I received an exorbitant quote that suggested a lack of enthusiasm for the job. (Keep in mind that the house is finished, with historic wallpapers, and the owner is well informed.)

The third contractor preferred by Unico arrived the day after an initial email and gave me a firm quote by the end of the same day. The price was not unreasonable and included all electrical work. I agreed to proceed.

pipefitting return duct

A six-inch opening for a return duct under the stairs had, at first, a jarring appearance.

On arrival, the contractor worked out most of the component routing on a map, with changes to be made as necessary. As my house has a gambrel roof, we discovered that we could not get past certain gambrel plate members without substantially weakening the structure. That required having to run the duct hose lines over finished walls in two rooms on the third floor, and in two closets. The decorative solution in one room was to hang a period tapestry over the lines. Perhaps not everyone’s solution, but it works for me.

On the ground floor, the map called for two wall returns, on either side of the staircase. In spite of this, the contractor wanted to put in floor returns, as they are easier to install. We had a bit of a go-round over that; I didn’t want floor grates, which fill with dirt. After discussing where to put the returns, the contractor started to cut into the wallpapered plaster under the staircase. After determining that off-the-shelf grates would neither fit in the space nor provide enough air circulation based on size, I came up with my own solution. After adjusting the openings, I fitted the air-return holes with two antique bank-teller grates with fine, wire-mesh backing. They look like they have always been there.

return with grille

The homeowner/author solved the aesthetics problem by covering the opening with an antique bank-teller grate.

Scheduled to take two weeks, the installation took a full month, including down time. Although I would caution “be careful what you wish for,” I would do it again. Yes, the plaster dust and the blown insulation that got disturbed created an awful mess, but the crew really was good about cleaning up each day. And, in the end, the Unico system is whisper-quiet and quite efficient. My allergies are less reactive and, with zones set at 74 degrees, the house is wonderfully cool, with comfortably low humidity. 

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