Arkansas HVACR NewsMagazine November 2021

HVACR NewsMagazine November 2021

Tech News

Airflow/Ductwork

your hand across the top of the outdoor unit is very helpful; in the cooling season, the air from the top of the unit should be hot, and it should be cold in the heating season. If you run your hand across the top of the outdoor unit and the fan is running but don’t feel any air, the motor may be running backward due to an electrical issue. At this point, one thing should be clear: a good technician will use their senses before making any measurements . Measurements are key, but if a technician can’t use their senses first, it’s likely that the measurements will only confuse them. Be observant and aware of how the system is operating by your senses before you begin measuring anything. Once everything is confirmed to be clean and set up properly, it’s time to let the unit run. Letting the system run 15- 20 minutes uninterrupted is standard. During this time, you will need to make sure the load on the space (either heating or cooling) is enough for your testing. If you start to notice a space dropping 5 degrees in 20 minutes, then you have a totally different sizing problem. But we'll save that for another article!

Airflow and ductwork are next on the list, and they’re probably the most important areas of the system to commission. Commissioning the air side of any system includes making sure the settings for the indoor unit are set up correctly and that the air delivery system (the blower wheel, condenser fan, the indoor and outdoor coils, the filter, the ductwork) is clean and not restricted. Again, it’s critical to use y our eyes to confirm that the motors are running and your ears to listen out for any abnormal sounds. Also, pay attention to any air leaks in the cabinet of the indoor unit on either the supply or return side. Observing the ductwork for kinks in flex and crushed metal pipe or looking for air leakage can help answer a lot of questions during the commissioning process. Your ears can help with this, too, because there may be an audible whistling sound from the cabinet of the indoor unit when air leakage is present. Use your hand to feel whether or not air is actually coming out of the supply registers and whether or not it is hot or cold (depending on the season). Running