DIY Network

Heating Up and Cooling Down: Installing the Mechanical Systems From "Home IQ" episode DHIQ-109

As framing is completed, the subcontractors arrive on-site to begin the rough mechanicals -- or first stage -- of the plumbing, heating, cooling and electrical systems. A guest talks about the open-web floor joists, which allow the subcontractors to run all of their systems through. Using the systems-integration approach, viewers learn the order in which the subcontractors install their systems.

The "rough" stage is nothing but the behind-the-walls working of the plumbing, heating, cooling and electrical systems. In a typical home these systems are designed separately, but for the high-tech Oberg home, "typical" is not part of the vernacular. For example, normally one engineer will design the heating-and-cooling system, one engineer will design the structural system and usually there's no engineer for the plumbing, which is just installed by a contractor.

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	Figure B

The building engineers at Ibacos recommended an integrated approach to designing and installing these systems. To accomplish this for the Oberg home, the engineers created a detailed set of drawings (figure A) for each subcontractor to follow. These systems-integration drawings enables each sub-trade to look at the drawings and go about their work while not only thinking about the task at hand but about the further process of an electrician, plumber or the heating-and-cooling subcontractor.

For the Oberg home, the first subcontractor to deal with this unique approach was the carpenter. An important element to this approach to designing an engineering house is the use of a floor-framing system where you can actually integrate the ductwork and plumbing systems. Since the floor joists (SpaceJoists®) are open-webbed, the subcontractors can run their systems inside the joists (figure B).

Note: With this system, the mechanicals workers (plumbing, electrical, etc.) aren't required to do drilling, cutting or sawing, which makes working with this type of system much easier and quicker.

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Order of Systems Installation

1. Plumbing comes first because it's restricted by gravity since waste must flow downstream, which means the piping must have a slope (figure C). The plumber also will install the steel pipes that carry the gas to the furnace and the fireplaces.

2. While the plumber continues his work, the heating-and-cooling subcontractor arrives to get started on his installation (figure D). With all the new technologies in the Oberg home, they have to think a little differently. Gary Gressang from White Heating (see Guests and Resources, below, for more information on Gary and White Heating) said this was a totally different installation from any White Heating had undertaken. "Register placement, sizing and even down to the ductwork were different materials and different applications," he said.

   Much of the heating-and-cooling ductwork has to be fabricated right on-site because many of the chases -- or the areas where the ducts will run inside the walls (figure E) -- are different sizes and have unforeseen interruptions.

   After fabrication the corners of each duct are sealed (with duct tape) for air tightness. Then the ducts are installed. First, all of the vertical sections, known as stacks (see figure E), are installed between floors. Then all the horizontal sections, known as trunks (figure F), are installed.

   Tip: Another step to ensure that ducts are air-tight is to add a special sealant -- called "Mastik" -- to all the duct corners and joints.

   In addition to the sheet-metal ducts being utilized, flexible ducts are used to make installation easier. You can have longer runs for turning corners by using flexible ducts. This type of duct is also sealed (figure G) for air tightness.

   Note: Part of the heating-and-cooling system is being made from fiberglass duct board in the Oberg house in order to cut down on noise. Minimal air noise is heard when the system is turned on when you use fiberglass duct boards.

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	Figure I