Arkansas HVACR NewsMagazine March 2022

HVACR NewsMagazine March 2022

Tech News

Pressure. New testing criteria will now require performance testing at 0.5 External Static Pressure to more accurately reflect the conditions that meet real time installed systems. Correct fan settings as required by manufacturer- The manufacturer understands air flow through the air handler or furnace, and it is up to the contractor to ensure those air flows are accurate at installation. Read the information supplied by the manufacturer for setting up fan flows accurately. If return statics are above 0.1 add more return air and or filter surface. If supply side statics are above 0.3, we must adjust the distribution system either by adding more supply air or reconfiguring the distribution if our rooms have the necessary duct sizing. Never adjust fan speed to lower static pressures as this can lead to inefficient equipment and or premature mechanical failures.

Adequate grill area for cfm-

As discussed in a previous section, return air or cold air returns remain at top the list for providing a chokehold on HVAC performance. The formula is simple. Required CFM divided by 2. 1200 CFM = 600 square inches of grill area Low restriction filtering is the second only to the above paragraph. One-inch filters should be abandoned immediately if you advertise as an expert on indoor air quality. Media filters several inches deep are required to keep air flow efficient and evaporators clean. Where delivered CFM of equipment is above 1200, more than a single filter of any type must be employed to keep static pressure low for efficient fan loads and noise levels.

Transition for airflow across the entire filter surface is a must, as air will not flow beyond a 22-degree arc. Anything greater and portions of the filter will not be utilized, and static pressure will be driven higher consuming more energy and creating more noise. Manufactures understand the issue and testing criteria for new equipment is about to change. Previously, testing criteria held the manufacture to test at 0.1 External Static

Appropriate plenum design with adequate surface area for tapping air supply-

Poor plenum design is rated third on contributing to poor air flow. Never change direction of the air flow less than 18” from the evaporator . If the coil case is substantial longer than where the top