An old AHU does not necessarily need a new AHU.

If the cabinet, coils, filters, and ductwork are still serviceable, replacing the entire unit may not be the most economical solution.

In many aging HVAC systems, the real problem is the fan system—especially when it relies on a belt-driven AC fan, fixed-speed operation, or outdated mechanical transmission.

That is where an EC fan retrofit or EC Fan Grid can make sense.

The key question is not simply “How old is the AHU?”

It is:“Is the AHU still structurally and thermally usable, while the fan system has become inefficient or obsolete?”

When Does an EC Fan Retrofit Make Sense?

An EC fan retrofit is worth evaluating when:

Complete AHU replacement becomes more appropriate when the cabinet is severely damaged, coils are undersized or beyond repair, air leakage is excessive, or the system requires a major capacity redesign.

Equipment age alone should not determine the decision. System condition and lifecycle cost should.

Why Replace an AC Fan with an EC Fan?

Traditional AHU fan systems commonly use AC motors with belts, pulleys, and separate mechanical components.An EC fan changes this architecture.

Pic.1 Comparison of different types of fans(Source|ebm-papst)

The motor and fan are integrated into a direct-drive assembly, eliminating the belt-and-pulley transmission system and its associated maintenance.

EC fans can adjust speed according to actual airflow demand, making them suitable for systems that operate under changing loads.

Multiple EC fans can operate in parallel. This allows airflow capacity to be distributed across several modules and can provide redundancy and easier maintenance.

Pic.2  Structure of EC fan(Source|ebm-papst)