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This is the 2nd house we have GC'd. We want to address concerns prior to having the blue prints finalized and contacting an HVAC company. One among a few concerns is the plumber and HVAC having problems. After research, we have decided we want rigid sheet metal ductwork.

Furnace and ductwork will be installed in finished conditioned space.
Preliminary plans attached show basement with red lines showing the main floor above.

a. About how far on either side of the furnace will the supply and return trunk lines need to run, as well as the trunk line for the zone heating? What might be the logical location for the zone trunk and a possible length?

basement plan with redlines showing what is on 1st flr

closed as too broad by isherwood, Ed Beal, ThreePhaseEel, Speedy Petey, wallyk Apr 7 '17 at 4:56

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • Welcome to SE. Please understand that we're not a discussion forum. Stack Exchange is a question-and-answer network that requires clear, specific questions. You're asking many things up there, and some of the questions are very broad. "Any ideas?" isn't usually a suitable question. Please edit to simplify and clarify the one thing you're asking, and feel free to post additional questions if you like. – isherwood Mar 28 '17 at 15:15
  • Are you acting as your own GC? This is what they get paid for. If so, you should also be able to rely on a good designer/draftsperson to help. At any rate, it's much to big a bite for a DIY site. – isherwood Mar 28 '17 at 15:17
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You don't mention which direction the floor trusses lay, but assuming they run the narrow direction above they it will be a little challenging but hardly unusual. The best bet is to get your HVAC contractor and truss designer together to spec out openings in the trusses for at least the main supply and return trunks. The truss designer is the expert, but I would expect the supply and returns to be separated by a few feet to avoid a large opening and a weak spot in the trusses. The HVAC designer might prefer the trunks and opening be centered over the furnace, to make connecting the furnace easier and to avoid the plumbing under the main floor bathroom. It means long runs to the foyer side of the house, but those are between trusses.

If you are seeking efficiency consider talking to a energy rater, specialist or Passiv house/efficient builder. You have a nice small, simple structure. With a modern tight (beyond code minimum) envelope and enough insulation you may be able to heat and cool with a few mini-split heat pump units instead of forced air. The savings on ductwork alone will pay for a lot of energy improvements, and you'll save money and energy for the life of the home. There are plenty of resources, Greenbuildingadvisor.com, Building Science Corporation and the Energy Vanguard blog are some of my favorites.

  • Add 8" to the basement, then you can run the duct work as a contractor normally would, below the joists. – d.george Mar 28 '17 at 11:45
  • Added info: Our Floor joist run parallel to the short ends. The energy efficiency is dictated by minimum IRC 2012 code- very tight. A Forced air system will be needed and mini-split heat pumps are not an option in Minnesota. – minmn Mar 28 '17 at 12:13
  • Today's mini-split units are capable of extracting usable heat down to 0F and below. A tight house in any continental US location can be heated with them. 2012 IRC is tighter than any code before it, but it is not "very tight" by today's definition. 2012 IRC mandates 3ACH@50 (3 air changes per hour at 50pascals), 2009 was 7ACH@50, but well built homes are below 1ACH/50, and Passiv house designs are designed to be below .3ACH/50. Remember, codes are the minimum requirements. There are almost always benefits to building beyond code. – mfarver Apr 2 '17 at 1:34
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Things to consider: Instead of all those swinging doors, and I see way too many, you may want to consider pocket doors in some areas. You don't have the door infringing or competing for floor space. They work great for cupboards and areas that don't need privacy locks, such as bedrooms. If this is a retirement house you should consider wide door ways for later years when help is needed. As for the duct work, make sure it is larger than usually installed. If not, the system will suffer from air noise due to air flow being faster than necessary. I come from yesterday when duct sizes were larger than they are today. If the installer says that is B.S. send him to my house. My installer did not do it my way and now I have a noisy system. Putting the duct work into a joist space (between joists) will cause installation problems and will not save ceiling height. --Put both high and low returns in every room. Single vent damper registers work great in the one that gets opened and closed. The upper grills are open in the summer to take the heat off the ceiling and the lower grills are open in the winter to grab the cold air off the floor. Cold air is heavier and warm air is lighter. My next house will have a double floor, the way houses used to be built. Single 3/4" floors are too weak, especially if you have heavy furniture.

  • Gah. Pocket doors are a user-experience disaster and a last resort, in my opinion. – isherwood Mar 28 '17 at 15:13
  • Nobody asked for your opinion!!! We have them all over our house and they serve us well. – d.george Mar 28 '17 at 19:24
  • I will say I am" sorry" for being so insensitive to someone else's comments. I was experiencing a moment of weakness. Everyone has an opinion. I just thought mine was the best. Sorry again. – d.george Mar 28 '17 at 23:16
  • No worries. Delete 'em and move on. – isherwood Mar 29 '17 at 0:56

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