ducts for new homes

Improper sealed ducts will reduce significantly the efficiency of any heating and cooling systems. Sealing them with mastic is important, but there are other features you should pay attention to. The ductwork design is also extremely important when building a new home…

Design

Bet on a straight and short ductwork for your new home. It will improve the energy efficiency of the ducts and diminish their leaking and thermal loss potential.

Location

If possible avoid locating your energy equipment – and ducts… - outside the home or outside its insulated space. Locating it in an non-insulated attic, garage or crawl space is not energy-efficient.

Work hard with your contractor in order to get a design that locates the ductwork inside your new home. To achieve it you must also to locate your water heating, ventilation and cooling and heating equipment inside your new home, in an as central position as possible.

Such location will make the duct design simpler, straighter and shorter, diminishing the potential for energy and thermal losses. And will also ensure that losses associated with air leaks and thermal flaws will not be entirely wasted.

Sizing

Pay attention to the size issue. Duct systems should carry enough air to heat and cool the house. Size should be calculated simultaneously with the installing of the heating and cooling equipment, to take into account its power and the home’s heating and cooling needs.

Do not accept a rule-of-thumb approach when estimating the size of the ducts. The contractor should use proper software and methods to estimate the best size for ductwork. An undersized duct system will not drive enough air to the rooms and will force the equipment to run overtime and to waste fuel.

Leaking

Ducts must be well sealed. And to achieve it, common duct tape is not a solution.

Mastic-type sealants and foil-backed tape are the ideal sealants. Do not forget: it’s much easier to seal ducts correctly during construction than attempting to seal them after the home is finished.

Also do not forget that if the ducts are located inside the home’s living space, the losses associated to leaks and lack of insulation will be less severe, but they do not disappear. If the heated or the cooled air isn’t driven to the intended rooms, there will be comfort problems, and in some sense losses are unavoidable…

See, for details: Duct sealing and Ducts Basics and Insulation

Insulation

In addition to sealing, supply and return ducts should also be properly insulated - even if the ducts are installed in the living room space. If there isn’t a proper insulation, heat and cool will be conducted through the walls where the ducts are located, and a significant part of the energy can be lost.

A minimal insulation levels of at least R-5 is a common reference for ducts located inside home (if the ducts are located outside, insulate them to at least R-8).

See, for details: Ducts Basics and Insulation