Where should filters be installed in relationship to heat exchangers or coils?

Filters should be installed upstream of heat exchangers or coils to ensure that they capture contaminants and particulates before they reach the critical components of the HVAC system. By placing the filter upstream, it prevents dirt, dust, and other impurities from accumulating on the surfaces of the heat exchangers or coils, which can hinder their efficiency and performance. This practice helps maintain optimal airflow and improves the overall operation of the system, thereby extending the lifespan of both the filters and the heat exchangers or coils. Moreover, it aids in reducing maintenance costs, as frequent cleaning or replacement of system components can be avoided when contaminants are filtered out before they cause problems. Installing filters downstream would mean that the debris could potentially block or damage heat exchangers or coils, leading to more significant issues within the system.