March 13, 2019

If you’re concerned about heating and cooling costs, closing vents in rooms you aren’t using probably seems like an easy way to save energy and money. After all, you’ll be cooling or heating less square footage, so it only follows that closing your vents would deliver savings.

The truth is that closing vents in unused rooms actually does the opposite. This can waste more energy because your air conditioner or furnace will be forced to work harder and push excess air to other areas of your home.

How Closed Vents Affect Pressure and Performance

Your system operates with a blower that pulls air from your house through your return ducts then pushes it back through the supply ducts. The system is meant for the blower to push against a maximum pressure difference. When you close vents in unused rooms, the duct system becomes more restrictive, and pressure increases. Depending on the type of blower you have, it will either ramp up the motor in an attempt to maintain the right airflow or spin at lower speeds and move less air.

The more vents that are closed, the higher the pressure increases. This will force cooled or heated air through leaks in the duct system and either moves less conditioned air for reduced comfort in occupied rooms or increase energy consumption.

You can think of closing vents as closing one of your nostrils and trying to walk at a brisk pace; you must either put in more effort to breathe or move less air through your nose.

Closing Vents Can Damage Your Air Conditioner or Heater

Energy costs aren’t the only concern when closing vents in unused rooms. This practice can also damage an air conditioner, heat pump, or furnace. Most systems today use a PSC blower that spins more slowly when vents are closed and reduce the amount of air delivered to the evaporator coil or heat exchanger.

When an evaporator coil gets too little airflow, the coil can get too cold and freeze. This can allow refrigerant to flow back to the compressor outdoors and cause damage. A heat exchanger in a furnace can also be damaged by low airflow, which can cause the heat exchanger to overheat and even crack. At Gunthers Heating, Cooling, and Plumbing Heating and Cooling, we take cracked heat exchangers seriously. A cracked heat exchanger is the most common way for dangerous carbon monoxide to enter the home. In most cases, replacing a damaged heat exchanger is not worth the cost, so we will recommend new furnace installation to correct the problem.

Gunthers Heating, Cooling, and Plumbing Heating and Cooling serves American Fork, Provo, and surrounding communities with residential and commercial heating, cooling, and plumbing. If you’re concerned about saving money on your energy bill, contact Gunthers Heating, Cooling, and Plumbing Heating and Cooling to learn about cooling and heating system maintenance.

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