Messages and Online Forum Q&A

Re: central air system

From: info@builderswebsource.com
Category: HVAC
Remote Name: 63.198.181.43
Date: 20 Jan 2001
Time: 09:56 AM

Comments

So long as you can supply enough volume of air and you have space to pass flexible heating ducts into the attic area, there is no problem with using ceiling heating ducts upstairs. In fact, it's quite common practice.

Clearly, it's more efficient to have the heating ducts in the floor, since heat rises. However, most homes with two floors don't have the luxury of putting the vents in the floor on the 2nd story...so they're often run through the attic.

Another trick is to run the flexible ducts through the attic...and terminate them onto sheetmetal chutes that fit between the wall cavity. Then, this enables you to vent near the bottom of the floor. If you do this, be sure to allow clearance for baseboard moldings or other finish materials.

I prefer the flexible heating ducts made with metal as opposed to the wire-framed versions which tend to rip easily.

Regardless of the approach you take, make sure you size your ducts and new furnace properly...and that you provide a good path for the air return.

A typical rule of thumb is to start with each planned vent, assuming it will be connected to a 6" duct. Anytime two 6" ducts merge, the diameter should increase to 8". Where an 8" and 6" duct merge, the diameter should increase to 10" and so forth. Working backwards, you'll be able to determine the required diameter of the duct supplying the 2nd floor.

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