Arkansas HVACR NewsMagazine September 2020

S tate, National, Chapter News Tech News

recently released a new manual for low load homes. The BTU per square foot requirement falls as insulation values rise. This reduces the cfm per square foot requirement by 50% or more. The LLH manual explains how to provide solutions for the lower BTU requirement; for example how to manage airflow in a 2,000 square foot home that only requires 1.5 nominal tons of air conditioning. DON’T BLAME EVERYTHING ON OTHERS As a contracting community, we must all move to educating our clients, whether they are homeowner, architects, builders, or remodelers. We must know all the facts prior to installation. We must understand our liability when we fail to document the scope of work in any contract. We should outline not only our work, but also what conditions exist at the time the equipment is installed (this does not have to be a complicated process). We must also research a few basic questions to be included in every bid document: • The existing heat load at the time the equipment was installed; • The area served by each system installed; and • Are changes imminent to the structure? If so, explain the impact for future reference. When all is said and done, let’s not forget the importance of an accurate load calculation on all homes, particularly high-value insulated (foamed). Because rules of thumb

prevail in the HVAC industry, many feel they can guess the load on the home by simply adjusting the rules to compensate for the added insulation value. This is a huge mistake on two fronts. First, where foamed or advanced insulation products are included, sensible loads are less than we would ever guess due to reduced infiltration. Second, latent loads are higher due to low air change and shorter HVAC run times. Plus, when we guess, there remains an inherent tendency to oversize. An HVAC contractor’s job is complex if we do it correctly. It may become more complex if the job includes high-value products as insulation material. It pays to understand the issues prior to installation of equipment. It also pays to understand the principles of building science when things do not work as we desire. When all is said and done, let’s not forget the importance of an accurate load calculation on all homes, particularly high-value insulated (foamed). It pays to understand the issues prior to installation of equipment. It also pays to understand the principles of building science when things do not work as we desire