How to Size a Central Air Conditioner for a Mobile Home

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While mobile home air conditioning units are based on the same technology as that of standard-size homes, central air conditioning for mobile homes is specialized. For this reason, ENERGY STAR created manufactured home cooling equipment sizing guidelines.

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HVAC installers use these guidelines to ensure that mobile homes have the proper fit in terms of heating and A/C units. HVAC equipment is not one size fits all. Due to their smaller size, mobile homes require smaller HVAC systems than standard-size homes.

ENERGY STAR Home Cooling Sizing Guidelines

ENERGY STAR is a nationally recognized energy-efficiency labeling program administered by the U.S. Environmental Protection Agency. The program was created to help consumers, business owners, and professionals, such as HVAC experts, to identify and promote products that are energy efficient. ENERGY-STAR-qualified homes are at minimum 30 percent more energy efficient in terms of heating, cooling, and water heating than homes built to the 1993 Model Energy Code.

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The standards in the ENERGY STAR sizing guidelines enable HVAC installers to correctly size air conditioning and heating systems for installation in mobile homes. It's important to have the correct-size cooling equipment for a mobile home, as oversized cooling equipment can be costly and can cause performance issues.

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Downsides of Improperly Sized Cooling Equipment

When a mobile home is outfitted with cooling equipment that has more cooling capacity than necessary, efficiency is compromised. Oversized equipment will turn on and off too often. This causes the equipment to wear out before its time and lowers the efficiency of the unit in general. Mobile home dwellers also pay higher cooling costs than necessary when the air conditioner size is too large. Moisture problems in the mobile home can result as well when the system is oversized. This can cause issues such as harmful mold and mildew in the home.

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ENERGY STAR Process to Choose A/C Size

The ENERGY STAR manufactured home cooling equipment sizing guidelines feature nine maps that cover the continental United States. The sizing table recommends cooling equipment sizes in tons. Maps are divided into counties and contiguous county sizing groups.

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The steps HVAC professionals take to choose A/C size for mobile homes using the ENERGY STAR guide include:

  1. Determine the square footage of the mobile home where the air conditioning unit will be installed.

  2. Find the county where the home is located on the guide's map. This will give you a sizing group number.

  3. Find the sizing number on the chart.

  4. Locate the mobile home's square footage at the top of the chart.

  5. The point where the square footage and sizing number meet is the correct tonnage for the air conditioning unit. This provides the ideal and most efficient cooling equipment capacity in tons for an air conditioner.

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On the chart, there are two tonnage numbers for each sizing group. This is the ENERGY STAR-recommended size, with the number on the left, and the HUD-recommended size on the right. Generally, these numbers are the same, but there is some variation. The ENERGY STAR numbers are considered superior in terms of energy efficiency.

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