Arkansas HVACR NewsMagazine March 2026

HVACR NewsMagazine March 2026

Tech News

equipment. The ACH must be measured accurately. One would think we should celebrate the milestone of beginning to control unintended air flow.

Why Blower

Door Data is Vital Tom Turner, Air Evangelist

So, what is the issue?

The fact that past construction has allowed uncontrolled air through the structure, kept carbon monoxide poisonings at lower levels. The blower door is vital when measuring a home for proper operation with combustion appliances are present. In a 2-ACH home carbon monoxide becomes of greater concern. If you remember mold issues from the early 2000’s in homes that were 4 -ACH or more, how bad can mold get in a home of 2-ACH or less? These same low ACH homes will suffer greatly if the environmental equipment is not sized correctly or if make up air is not provided in calculated quantities to overcome vent hoods, bath fans, and other general ventilation requirements.

Reviewing history is sometimes helpful.

Construction codes, inspection jurisdictions and utilities across the country require Manual J calculations when replacing or altering capacity in HVAC equipment. I have no idea how many load calculations we have performed or reviewed, but one section of the load calculation always causes consternation early on. The first Manual J for the business was completed in about 1977 when remodeling a two-story structure. Test equipment popular today was not available. To this day in the year 2026, ninety percent of the time, folks still do as I did. They are guessing at building tightness. Guessing leads to oversizing the equipment just to make sure people are comfortable, while forgetting Manual J and Code allows 25% oversizing when fudge factors are combined. With today’s materials and processes, it is becoming the norm to choke unintended air flow off with remarkable success. Oversizing becomes a much more apparent issue when the envelope is controlled. Only a decade ago construction struggled to get homes below 4 ACH. Homes where heat pumps are installed must have an approximate ACH of 3.5-ACH or less to be sure they function efficiently. Today 2-ACH is readily achievable, but standing at the curb looking at the home will never give you the data necessary to carefully select To this day in the year 2026, ninety percent of the time, folks still do as I did. They are guessing at building tightness.

ERVs & HRVs

Kitchen Exhaust

Bath Exhaust