What Does it Mean to Air Balance My Air Conditioning System?

Have you ever experienced when certain rooms in your home are hotter or colder than the rest of the house? You run the AC all day and the front room, or the back bedroom, just won’t cool off?

There could be a lot of reasons for this, like low insulation, large south facing windows, etc. But one of the most common is that the air flow in you air conditioner is out of balance. 

What is an Air Balance?

When your HVAC system was designed using Manual J, a lot of calculations went into how many BTU’s (British Thermal Units) were needed to cool and heat your home. Another set of calculations went into designing the ductwork and determining how much airflow was needed in each room to deliver the designed BTU’s, along with how best to deliver them. 

The final product of all of this work is what we call an air balance, the perfect balance of airflow to each room to deliver the designed BTU’s. 

What Went Wrong?

The fact is, the person that designed the system, ductwork and all, is usually not the person who installed it. Poor installation can throw off the air balance very easily. Not to mention, systems degrade over time which can throw off the air balance. Some of the key factors would be:

  1. Is the flexible duct pulled tight?
  2. Are the duct runs too long?
  3. Are there any sharp bends or angles in the ductwork?
  4. Is the ductwork hung correctly?
  5. How are the ducts positioned on the plenum?
  6. Do the ducts have dampers, and if so, are they open?
  7. Are all the ducts still securely fastened and sealed at their insertion and origin points?
  8. Is the blower speed set correctly to maintain designed static pressures?

Flexible ductwork that is loose or sagging will create friction in the airflow inside them and reduce the volume of air delivered to the room. You get this same issue if the duct run to the room in question is too long without tapering, or stepping down the duct size. You get even more friction with sharp bends and turns. If the ductwork isn’t hung correctly it can rest on the insulation which renders the insulation useless causing the air in the duct to convert to the temperature of the attic it is housed in. 

You also have to consider where the ducts are placed on the plenum. Certain parts of the plenum inevitably end up with higher pressures causing more air to flow through the ducts attached at those points. 

Another common issue is that the ducts have dampers installed but the dampers were never tightened. This means that over time, as air flows across the damper it can slowly close itself off, restricting or stopping airflow entirely. 

And finally, are the ducts still connected and sealed. If the ducts have come off the plenum, or pulled back from the boot in your ceiling they won’t deliver air as designed. If they aren’t sealed then they will dump the conditioned air into the attic rather than the living space. 

How Do We Solve This?

The solution is to have the air in the system rebalanced. The first step is to use an anemometer to measure the airflow at the vents in each room in your home. We use this data to determine the severity of the issue as well as which vents are under or over-performing. 

Next the technician will inspect the system and all ductwork. He will check to see if the ductwork is pulled tight, tapered correctly, void of any sharp bends, tapered correctly, connected to the plenum, sealed, and also make sure if dampers are present that they are open. 

Some solutions are easy, and cheap. Others are more costly. For example, if the system was designed poorly it may be necessary to redesign or reconfigure it. We may need to reposition ducts on the plenum, install dampers, and balance the system manually. 

Needless to say, the issue can be resolved. There is no need to continue living uncomfortably in rooms that won’t heat or cool properly. 

Call Prestige Air

If you experience problems with your heating and cooling call Prestige Air. Our expert service professionals have the training and experience to keep your HVAC system in tip-top shape all year long. Call (817) 200-7215 to make sure your heating and air conditioning are ready for the season!

Prestige Air proudly serves Northeast Tarrant County and the Fort Worth, Texas area including Hurst, Euless, Bedford, Colleyville, Grapevine, Southlake, Westlake, Trophy Club, Keller, Watauga, Haltom City, and North Richland Hills.

We look forward to serving you and your household!

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At ​Prestige Air, we’re a team full of passionate heating and air conditioning technicians who care deeply about our clients. We know that issues with your heating and cooling can be a headache and our goal is to get your issues resolved ASAP so you can get back to living your life stress-free.

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