What are the building code requirements for installing a heat pump air handler (indoor unit) in the attic?

Thursday, September 5, 2019

When any appliance, including an air handling unit is placed in an attic, there is a potential safety risk for the living space below the appliance due to water leakage. Also, a person entering the attic to service any appliance must be able to get to it safely, and then be able to work around the appliance on a stable surface. Here’s how the Residential Edition of the Florida Building Code (FBC M1305.1.3) and the International Residential Code (IRC) address these safety issues: 

  •  There must be an attic access opening large enough to remove the appliance, but not less than 30 inches by 22 inches, and a clear passageway not less than 22 inches wide by 30 inches high.
  •  The passageway from the appliance to the opening must be unobstructed and large enough to remove the appliance, with continuous solid flooring a minimum of 24 inches wide and maximum of 20 feet long. There are two exceptions to the passageway requirements. The passageway floor is not necessary if the appliance can be serviced from the attic access opening and, when the passageway to the appliance is unobstructed and not less than 6 feet high and 22 inches wide for its entire length, it can be as long as 50 feet. (see note below for Energy Conservation restriction in Florida that overrides and reduces the maximum length allowed)
  • There should be a level floor in front of the service side, or sides, of the appliance a minimum of 30 inches by 30 inches.
  • A luminaire (light fixture) and receptacle must be installed near the appliance. The luminaire should be controlled by a switch near the attic access opening.

Florida Energy Code Override on Attic Air Handler Passageway

    The Energy Conservation section of the FBC has specs for installation of an air handler in the attic that are a more restrictive than the general appliance requirements, such as that the passageway can only be a maximum of 6 feet long, a warning sticker is required, and a catch pan with drain or automatic shut-off/warning is necessary (FBC 403.3.6). See our blog post What are the Florida Building Code Energy Conservation Code requirements for installing an air handler in the attic? for complete details.

    And here’s an example of how not to install an attic air handler.

    Incidentally, installation of an air handler in the attic is the least energy efficient location you could choose. Go to our blog post Should I move my air conditioner into the attic? for more on this.

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Here’s links to a collection of our blog posts about ATTICS:

 What are the mistakes to avoid when doing attic improvements? 

 What are the hazards to avoid when going into an attic? 

 What is the most common type of roof-to-wall attachment?

 Is an attic required to have a light by the building code?  

 How do I safely remove a dead rodent (rat, mouse or squirrel) from the attic?

 What are the common problems with attic insulation? 

 How do I safely clean up rodent (rat, mouse or squirrel) urine or droppings the attic?

 Why is there no attic access hatch in the house?

 What is the building code requirement for an attic access hatch, scuttle, or door?

 Why is vermiculite attic insulation a problem for both buyers and sellers of a home? 

 What are the code requirements for NM-cable (nonmetallic-sheathed cable or Romex®) in an attic? 

 What are the warning signs of a dangerous attic pull-down ladder?

 Do home inspectors go on the roof? Do they get in the attic?

 How much of a roof truss can I cut out to make a storage platform in the attic? 

• When was a fire separation in the attic first required between sides of a duplex? 

   Visit our ROOF AND ATTIC page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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