Duct Airflow Problems

It isn't unusual to find duct systems undersized for the heating output of the furnace. Undersizing means that the ducts' cross-sectional area is too small. A stubbornly high supply-air temperature or portions of the conditioned space that are uncomfortable may indicate a duct-sizing or duct restriction problem.

Ducts are often restricted by furniture placement, closed doors and dirt registers. A test involving opening the door to a furnace's blower compartment during operation can provide information about duct restriction. If opening the lower compartment door reduces supply temperature significantly, then improving return air will usually improve comfort and boost efficiency. Improvements to return air include:

1) Cutting off interior doors to allow air to return from rooms, which have no return register.
2) Installing vents in doors or through walls, or installing ducts in ceilings to allow air to return from rooms, which have no return register.
3) Installing a new return duct leading from a hard to heat area directly to the furnace cabinet.
4) Cleaning registers, blowers and air conditioning coils.

Without getting into major reconstruction, first check your house. HZG sees weekly supply registered covered by dressers, beds, drapes, etc. Be smart; let the air FLOW.

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