Arkansas HVACR NewsMagazine May 2020

S tate, National, Chapter News Tech News

Because no coil is 100% efficient, there will always be some air molecules that leave the coil warmer than others, this causes the airstream to be warmer overall and decreases the RH of the air stream. You will notice when a system has a higher coil air velocity (speed) it will have a higher bypass factor (lower supply humidity). When you run lower coil air velocity, the bypass factor will drop and the supply RH will increase. There is also some heat added by the blower motor and possibly even the cabinet or supply ductwork. This added dry bulb heat results in a warmer airstream and thus some additional moisture capacity. Imagine a slight expansion of the sponge due to heat from the duct walls and the blower motor. Once that supply air exits the duct and mixes with the room air, it is allowed to “expand” again and the relative humidity drops below what it was initially. This is why supply air has a high RH in cooling mode.

Bryan Orr, HVAC School ( Founder / Podcaster / Dad of 10 ) Bryan Orr is a lifelong learner, proud technician and advocate for the HVAC/R Trade

There Is No Time Like to Present

• Listen to a podcast • Tune in to a webinar • Read installation instructions • Read a service manual • Ask for help to understand something you are experiencing in the field • Practice brazing • Study for a NATE exam • Take an EPA 608 test • Thank your coworkers for their hard work • Thank your employer for the career opportunity • Enroll in a fall class at a local college • Take time with your family • Read the Bible • Reconnect with your faith

Here is a video we did on the topic –