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As anyone with central air conditioning can tell you, it’s a summertime necessity. But central HVAC systems aren’t inexpensive to operate, and that leads some homeowners to go looking for ways to save money when the mercury rises. One of the ways they may try to do it is by closing the vents in rooms they’re not using.

At first, that may seem like a logical thing to do. After all, if you aren’t in a room, why pay to keep it cool? But closing vents in unused rooms isn’t the cost-saving hack that many believe it to be. Instead, it could lead to higher costs in the short and long terms. Here’s why.

Closed Vents and HVAC Sizing

The primary reason that closing vents in unused rooms won’t save you money on your HVAC operating costs has to do with how your HVAC system achieves efficient operation. That has everything to do with size. An ideal home HVAC system should be powerful enough to cool your home but not so large as to be wasteful. And everything in the system — from its air intakes to its ductwork — plays a part in that calculus.

In practice, this means your HVAC system and your home’s ductwork are a matched pair. The former produces the necessary airflow, and the latter carries it to where it’s needed. When you close vents, you’re increasing the air pressure in your ducts, and that puts added back pressure on your HVAC system. This extra pressure forces it to work harder to push air through the system. In other words: You’re forcing it to run less efficiently.

The Consequences of Closed Vents

It’s also worth noting that closing vents in your home won’t just lead to poor operating efficiency; it can also cause damage to your whole HVAC system. For one thing, the increased pressure in your ductwork can create air leaks that route cooled air into the unconditioned parts of your home. And once those leaks happen, they’re permanent. From that moment on, you’ll be paying to cool the insides of your walls and ceilings, but that’s not all.

When you close vents in your home, you may also deprive your HVAC system of sufficient air intake. That can lead to frozen evaporator coils and other damage that will shorten the life of the system, and it’s the kind of damage that might not be obvious right away. Most of the time, you won’t notice the symptoms of frozen evaporator coils until your HVAC stops producing cold air at the return vents. And by then, your HVAC system might require extensive — and expensive — repairs.

The Science of Heat Transfer

By now, you might be wondering why your home even has registers that close if doing so is so bad for your HVAC system. That’s an excellent question. The reason is that most HVAC systems operate as a single zone. That means they control the temperature of your home using a single thermostat. In a setup like that, it’s necessary to have some way of controlling airflow to individual rooms. However, your vents aren’t meant to stay closed for long periods.

Even if they were, there’s one last thing that makes closing your vents a bad option to save money. It’s the laws of physics. Inside your home, heat will naturally travel from the warm areas of your home to the cooler areas. It’s called the heat sink effect, and by closing the vents inside one or more unused rooms, you’re playing into its hands. You’re creating artificially warm zones that bleed into the cooled rooms, all while forcing your HVAC system to cool those rooms with a fraction of its potential power.

Open Up for Savings

The bottom line here is simple. If you want your HVAC system to work at peak efficiency, don’t close the vents in your home. Instead, keep them all open, in addition to opening as many interior doors as possible. Doing so lets your HVAC system move air around your home without any artificial barriers to deal with. That’s just what a central air conditioning system does, and they’re quite efficient at it — if you get out of their way.

Another thing that you can do is to see to your HVAC system’s maintenance needs. Here at Texas Pride, we’ve been serving the Houston area with pride since 1983, and our expert HVAC technicians know how to keep residential HVAC systems working at peak efficiency. We also sell, install, and service a variety of other heating and cooling, air quality, and refrigeration technologies that make your home as comfortable and inviting as possible.

So, contact us today if you want to be sure your HVAC is ready to handle the heat of the Houston summer. We’re always there when you need us.

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