Heating & Cooling & Your Registers

Heating & Cooling & Your Registershand closing a heating register

Closing off heating or cooling registers is a common practice and most homeowners don’t realize this can be a costly mistake.  You may think it’s going to cut down on your heating or cooling bill when in fact, it does the exact opposite and actually increases your energy bills!  The kicker is that it could actually damage your furnace and shorten its lifespan.

It turns out that you also increase the chance for what is known as the static pressure inside the ductwork of your home.  Higher static pressure is going to affect the airflow through your furnace and to your entire home.  If you have a standard blower motor on your furnace, higher static pressure is actually going to slow down the fan and decrease airflow to the entire house.  It can actually get low enough that the heat is created inside the furnace is unable to get out quickly enough and the furnace can overheat and hit the high limit, causing it to shut down.  Repeatedly running on a high limit is terrible for the furnace and will significantly shorten the life of the components, especially the heat exchanger.  The problem is similar in the summer with air conditioning – low airflow can lead to a frozen coil which could lead to liquid refrigerant making its way to the compressor which can kill that vital component in short order.  In other words, you can literally destroy your important and expensive heating and cooling equipment with something as seemingly harmless as closing a few vents.

If you have a newer, energy-efficient furnace equipped with an “ECM” motor, higher static pressure will cause the motor to use more energy to keep up with the extra pressure.  This results in higher utility bills along with shortening the lifespan of the blower.

If you have an older furnace, it may have a “PSC” blower motor that only operates at two speeds: on and off. So, when these motors work against extra pressure, the blower runs at a slower pace. And if the motor can’t pull as much cool air over the heat exchanger,  it will eventually overheat and crack, leading to thousands of dollars in repairs.

Other counter-productive issues include increased duct leakage, decreased comfort, and increased energy use.  It’s always best to call a professional if you have the urge to close off any part of your home so you can be sure it makes sense and doesn’t cause damage that could cost you in the end.


  • Have a skilled heating contractor inspect your ductwork to ensure that it’s properly sealed and free of any leaks.
  • Have your furnace inspected annually and cleaned every few years to prevent blockages and other issues. If your ductwork also needs cleaning, now’s a good time to have that done as well.
  • If your furnace is in need of replacement soon, go with a newer, energy-efficient model. Most new furnaces feature an annual fuel utilization efficiency (AFUE) rating near 95, whereas older furnaces are only half to two-thirds as efficient as their modern counterpart

To find out more about the drawbacks of closing air vents in your home, contact the professionals at Frontier Heating today for your heating and cooling needs.

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