Differential pressure is often used to monitor which condition in HVAC systems?

Differential pressure is often used to monitor which condition in HVAC systems?

• A. Temperature rise
• B. Filter condition
• C. Duct leakage
• D. Humidity increase

Answer: (B)

Differential pressure across an HVAC filter is a direct indicator of how dirty or clogged the filter is. When the filter is clean, air flows through with little resistance, so the pressure on the upstream side and downstream side is almost equal. As dust and debris accumulate, the filter’s resistance to airflow increases, causing the pressure difference to rise. By monitoring this pressure drop, the system can determine when the filter has become sufficiently loaded to warrant replacement or cleaning, helping to maintain proper airflow, energy efficiency, and indoor air quality. Temperature rise, humidity increase, and duct leakage are monitored by different indicators or tests. Temperature rise reflects heat gain or cooling effectiveness rather than filter condition. Humidity relates to moisture content in the air, not the filter’s resistance. Duct leakage is usually assessed through whole-system pressure tests or localized duct tests, not by the pressure drop across a filter.

Differential pressure across an HVAC filter is a direct indicator of how dirty or clogged the filter is. When the filter is clean, air flows through with little resistance, so the pressure on the upstream side and downstream side is almost equal. As dust and debris accumulate, the filter’s resistance to airflow increases, causing the pressure difference to rise. By monitoring this pressure drop, the system can determine when the filter has become sufficiently loaded to warrant replacement or cleaning, helping to maintain proper airflow, energy efficiency, and indoor air quality.

Temperature rise, humidity increase, and duct leakage are monitored by different indicators or tests. Temperature rise reflects heat gain or cooling effectiveness rather than filter condition. Humidity relates to moisture content in the air, not the filter’s resistance. Duct leakage is usually assessed through whole-system pressure tests or localized duct tests, not by the pressure drop across a filter.