Arkansas HVACR NewsMagazine September 2021

HVACR NewsMagazine September 2021

Tech News

Bulb temperature and Wet Bulb temperatures, we then then solve for Dew Point , Humidity Ratio , Relative Humidity , Specific Volume and Specific Enthalpy . These measurements and a basic understanding of their relationships are necessary to grasp the performance of air and how to influence air to behave under mechanical influence. We must recognize any time one measurement of air is altered, all measurements are changed.

The same goes for sensible capacity. Generally, latent capacity is 10% to 30% of total capacity. Engineering will reflect a decrease in latent when an evaporator maintains high sensible performance and an increase in latent as capacity wanes. The state of Arkansas is rated as warm and humid, and we should caution any adjustments out of the to 350 to 400 cfm. While 410A refrigerant is more efficient overall, sensible capacity is enhanced slightly with cfm readings being maintained close to the 400-cfm mark. In instances where the air is significantly more dry than typical Arkansas conditions, you may speed up air flow to minimize effective latent capacity losses.

Regardless

of

whether

the

refrigerant delivery is fixed, unloading or variable, evaporators must be sized properly,

It is a popular mistake to believe latent capacity can be shifted to address sensible loads. Sensible equipment loads mark the ability of the equipment to change air temperature and be measured with the use of a thermometer. Latent capacity is the ability of the equipment to remove vapor heat (dehumidify) from air moving through the evaporator. This change of state produces condensate and moisture must be removed from the dwelling via the condensate drain. This change of state depends on current conditions of the air and is a constantly moving target, so latent capacity is not a fixed number. The only time the evaporator has the nameplate capacity, is when operational conditions match the testing criteria.

and air handling equipment instructions must be followed to the letter. Oversight of proper sizing results in limited dehumidification, uncomfortable conditions, and shortened equipment life. As our housing stock becomes more efficient at maintaining temperature with encapsulated attics and crawl spaces, we must comprehend the change in capacity requirements are reduced significantly. If improvements are ignored and rules of thumb are employed as an alternative to providing an accurate load calculation, all areas of performance, efficiency and reliability will be jeopardized. Airflow or CFM per square foot is largely overlooked as a comparative safeguard the home is being sized appropriately.