Where should air filters be located according to code requirements?

• A. Downstream from heat exchangers
• B. Upstream from heat exchangers
• C. Within the ductwork
• D. Near the thermostat

Answer: (B)

Air filters should be located upstream from heat exchangers according to code requirements. This positioning is crucial for several reasons. By placing the filters upstream, they can effectively trap dust, debris, and other particulate matter before it reaches the heat exchanger. This not only helps maintain the efficiency of the system by preventing clogging but also extends the lifespan of the heat exchanger and other components by reducing wear and tear.

Filtering the air before it reaches the heat exchanger ensures that the air being heated or cooled is clean, which promotes better indoor air quality. Additionally, this proactive approach can prevent the filters from becoming saturated with contaminants and thus maximize the overall efficiency of the HVAC system.

The other locations, while they may seem plausible, do not provide the same level of protection and efficiency. For instance, placing filters downstream would allow contaminants to reach the heat exchanger, potentially leading to operational issues and reduced system performance. Similarly, positioning filters directly within the ductwork or near the thermostat may not effectively capture airborne contaminants before they can cause issues within the system. Therefore, the recommended approach is to ensure filters are installed upstream from heat exchangers to maintain optimal system performance and air quality.