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Will my HVAC heat and cool better if I close off four ducts?

My new 3.5 ton 15 SEER hvac is servicing a 3000 square feet house. I know, now, I should have bought at least a 5 ton. But, it is what it is. The system isn't cooling the far side of the house as well as the side closest to the unit. If I close off the four ducts (not close the vents) that serve the far side of the house, will the system put out better heat and air on the sides still connected to the unit?


The contractor did not offer a 5 ton unit. I trusted he'd done a thorough evaluation and offered only what was necessary. It was after I had to call a different contractor in, that I learned I should have bought a 5 ton. I plan to use a ductless unit on the side in which the ducts will be capped off. Also, there are 10 trees that protect this side of the house from nature's elements.

3 Answers

  • 1 decade ago
    Favorite Answer

    In most cases closing off registers only creates additional problems. If the issues are duct related you can install 15 tons and not see any change. The square footage of your home generally has the least impact on air conditioner sizing. It is east and west glass. I can take the same house and rotate it 90 degrees and change cooling load by 2 or 3 tons!

    Plus if you shut the registers and leave the doors open the heat in those rooms is just going to move to the cooler rooms on it's own. Heat goes to cold.

    Now if you were told and shown that you needed 5 tons and you decided on 3.5 I do not know what help I can offer. I guess we need to know how it worked prior to the new unit.

    Source(s): hvac contractor 4 decades
  • Anonymous
    1 decade ago

    Yes it will help, but what you should really do is have a heating/cooling contractor come in and measure the air flow in the duct work. They can "balance" the system so you will get the best out of your unit. It's worth the few dollars it costs. Also see about having your duct work insulated if it's not now. Good luck !

  • 1 decade ago

    not likely, as the hotter rooms will always radiate heat, the system will have to work hard regardless. you should consider upgrading the system, many times it only requires a larger capacity compressor, or install an additional 3.5 or 2 ton system so that they work together.

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