Arkansas HVACR NewsMagazine March 2020

S tate, National, Chapter News State national Chapter News

provides a rough in or at final test option, there is a big question as to which the HVAC dealer should select. If my numbers are right, there is a penalty for running the test when the air handler is in place due to the code allowing 2% leakage for the air handler. Check it out and tell me what you find. Building Cavities Though a common practice in the past, this does not represent a change to what we have been doing since 2015. Duct Buried in Insulation For almost two decades, some have championed ducts in attics being suspended. That was the plan for the Arkansas 2014 code but the Energy Office allowed ducts to be on or between ceiling joists as an additional option. The option to “lay” or suspend was a result of the Association providing data that proved there would be less loss or gain in the duct if it were on the ceiling with attic insulation surrounding it. The 2018 IECC minimum insulation is a function of meeting the insulation requirement of the conditioned space. Of course the duct is still required to have a minimum of R-8 per 403.3.1 and meet the vapor barrier standard. R403.3.5 Building cavities (Mandatory). Building framing cavities shall not be used as ducts or plenums.

R403.3.6 Ducts buried within ceiling insulation.

Pipe Insulation Refrigerant as well as condensate lines must have R-3 or greater. R403.4 Mechanical system piping insulation (Mandatory). Mechanical system piping capable of carrying fluids greater than 105°F (41°C) or less than 55°F (13°C) shall be insulated to an R -value of not less than R-3. Where supply and return air ducts are partially or completely buried in ceiling insulation, such ducts shall comply with all of the following: 1.The supply and return ducts shall have an insulation R -value not less than R-8. 2.At all points along each duct, the sum of the ceiling insulation R -value against and above the top of the duct, and against and below the bottom of the duct, shall be not less than R-19, excluding the R -value of the duct insulation. 3.In Climate Zones 1A, 2A and 3A, the supply ducts shall be completely buried within ceiling insulation, insulated to an R -value of not less than R-13 and in compliance with the vapor retarder requirements of Section 604.11 of the International Mechanical Code or Section M1601.4.6 of the International Residential Code , as applicable. Exception: Sections of the supply duct that are less than 3 feet (914 mm) from the supply outlet shall not be required to comply with these requirements.