How Tube Expansion Improves Coil Heat Transfer

If there's one manufacturing step that separates a great coil from a mediocre one, it's tube expansion. Yet it's invisible in the finished product.

Here's what it does and why it matters so much.

The problem: air gaps

When tubes are first threaded through fins, tiny air gaps remain between them. Air is an insulator — those gaps throttle heat flow from fin to refrigerant.

The fix: mechanical expansion

Expanding the tube presses it firmly against every fin, eliminating the gaps and creating continuous metal-to-metal contact. Heat now flows freely across the whole coil.

Why it's permanent

A properly expanded bond doesn't loosen over thermal cycling, so performance holds for the life of the coil. It's a core part of how AGH manufactures every coil.

What to ask

Ask whether coils are mechanically expanded — not just assembled. It's a simple question that reveals a lot about build quality.