scope:

Manual LLH deals with the unique HVAC design issues associated with homes that exhibit low cooling and/or heating loads (per Manual J^® load calculations) and identifies equipment options / approaches to address these issues. The manual augments the explicit instructions provided in the ACCA residential HVAC design process … load calculations, duct design, equipment selection, grille/register selection and placement, zoning, and dehumidification for residential applications; per the underlying ACCA Manuals J^® / D^® / S^® / T^® / Zr^® / SPS^® / RS^®.

Part 1 of Manual LLH addresses the specific challenges associated with using small tonnage HVAC systems that are needed in low load homes:

• low equipment airflows (a room air mixing challenge),

• increased home ventilation requirements (an equipment selection challenge),

• equipment low latent capabilities (an equipment selection challenge),

• higher than normal latent needs (an indoor humidity control challenge).

Part 2 of Manual LLH illustrates six 'example solutions' using representative equipment offerings available today:

• small duct high velocity (SDHV) equipment,

• ductless mini-split equipment,

• fan powered mixing boxes,

• air-zoning dampers for capacity deployment,

• engineered bypass air,

• conventional OEM equipment and ductwork with supply air nozzles.