ECONOMIC CENTS: HVAC Systems and Air Flow Go Hand-in-Hand

Dirty filters, built up air pressure cause for inefficiencies in many homes.

by Bruce Saller

The heating, ventilation, and air conditioning (HVAC) system works hard enough on both cool and warm days to keep people comfortable. Don’t make it work harder by restricting its airflow. 

A dirty air filter can reduce your system’s efficiency by anywhere from 5% to 15%. To maximize an HVAC system, replace the air filter every month or two during the heating and cooling seasons.

Dirty air filters are easy to replace, and critical for maintaining a system’s efficiency. But this isn’t the only thing that can block air flow.

Another issue can be a blockage of the return air path. 

Most systems have one or two central air ducts that return air to the HVAC unit. Closed doors can restrict the return airflow. To ease this problem, ensure that the gap between interior doors and the floor is between ½ and ¾ inches

If the gap is smaller than that, air pressure can build up in the room causing air to be forced outside through gaps in windows, electrical outlets, lights and bathroom vents.  This air is replaced by outside air pulled into other rooms, which then needs to be heated or cooled. 

It’s easy to determine if air flow is inadequate. Simply close a door until the latch touches the strike plate, and then see if the door quickly shuts.  If it does, you have restricted air flow. To reduce or eliminate this problem follow the following steps:

1.      Leave doors open where possible.

2.      If you need to keep a door closed:

a.      Remove rugs from around door bottoms.

b.      Consider cutting off a portion of the door bottom to make a ¾ inch gap.

c.     Close vents in the room no more than 75% of the way.

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