Round Inlet/Round Outlet (VRRF) units are designed to improve energy efficiency and reduce overall operating costs in existing systems.

Typical VRRF retrofit applications include:

• Bypass/replace existing mechanical regulator (air valve)
• Upgrade building and/or unit controls (e.g. Pneumatic to BACnet™) with or without replacing the mechanical regulator (air valve)
• Convert Constant Air Volume System to Variable Air Volume System
• Convert pressure-dependent Variable Air Volume System to pressure independent Variable Air Volume System (e.g. Trane VariTrac™)
• Convert Multizone (Dual Duct) Systems to Variable Air Volume System

VRRF units are also applied in non-retrofit or new applications, notably small building variable air volume systems also known as Zoned Rooftop Systems.