Causes Of Poor Air Flow In An Hvac System

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Homes with central heating and air-conditioning systems rely on ductwork to distribute warmed or cooled air throughout the house. These ducts carry air from the furnace or air conditioner to the rest of the house.

Today’s ductwork consists of insulated flexible tubes that snake across the attic floor or under the house. Unfortunately, heating ducts are out of sight and often out of mind. Homeowners wouldn’t put up with leaking water pipes. But ductwork †carrying air instead of water †can leak for years, without anyone knowing it. Water damage is immediate, but the only reflection from poor ductwork will be increased heating and cooling costs.

Ducts can leak †anything that punctures a duct will cause lost air. This could be as simple as a protruding nail or staples used to hold the duct together. Then, too, joints and junctions where two pieces of duct come together may separate over time †especially if duct tape was used to seal them. Contrary to the name, duct tape is not very good at sealing ducts together. It fails in very hot and ...
... very cold conditions. It is better to use a mastic †a viscous sealant that is painted on.

Builders sometimes even forget to attach ductwork together or to connect it to the vent in the wall. As a result, an open duct wastefully pumps conditioned air into the attic or under the house, while the room it is supposed to serve never gets comfortable.

Poor air flow in an HVAC system also occurs when ducts are blocked or kinked. Just as a pinched garden hose cuts down the flow of water, a kinked duct drastically reduces the flow of air. Kinking can happen when ducts are run along tight corners, or into tiny spaces… Make sure ducts are properly supported, and don’t sag, twist or bend overmuch, and they have no gaps or breaks.

Design is important as well. Ducts that are too small for the volume of air are improperly designed. A duct that is too large in one room may leak conditioned air that should be going do a different room in the house. The air conditioner or heater may be either undersized or too large for the duct system, providing too little or much more pressure than the system was designed to handle. Often, builders may try so skimp on materials and use whatever they have in stock, instead of ordering the correct specified equipment.

If its duct system is poorly designed or poorly installed, a house will be inefficient, no matter how well insulated it may be, or how perfect its furnace and air conditioner are. That’s why it’s a good idea to have your duct system examined for leaks, blockages, and just poor design. Air conditioning companies familiar with duct testing can perform the examination, and your local utility may give you a sizable rebate when you have it done. You may be amazed at the monetary savings and the dramatic increase in comfort.

There are many causes for poor air flow in an HVAC system. While many of them are correctable, it takes time and effort to find the problems, as ducts are one of the more hidden aspects of an HVAC system.