How Choosing the Right Coil Can Optimize Single-Duct VAV Systems
When it comes to commercial HVAC air distribution systems, single-duct VAV systems with hydronic reheat are one of the most popular in North America. As decarbonization and electrification efforts continue to impact the built environment, it is critical to maximize the efficiency of these systems and reduce their natural gas usage.
Condensing gas boilers are a common solution with lower hot water supply temperatures to improve efficiency, but as those supply temperatures drop, buildings become harder to heat.
One of the main ways to improve the efficiency and reduce the natural gas usage of condensing gas boilers is to decrease the hydronic system’s return water temperature back to the boiler.
 |
 |
 |
| While the commonly seen two-row coils (left) and three-row coils (center) are often inadequate, specialized low water temperature coils (right) can improve the efficiency of the VAV system | ||
Unfortunately, the commodity coils we commonly see in the market are often insufficient: while two-row coils can underperform for heat transfer, three-row coils come with a high air pressure drop.
Reviewing three-coil performance (table 1) brings up a question: Does it make sense to improve the efficiency of the hydronic system to degrade air handler fan performance with high air distribution pressure drop?
| Table 1. Three-Row Coil Performance |
 |
This is where Low Water Temperature (LWT) Coils from Price come in. These coils leverage an oversized casing and optimized coil circuiting, providing lower return water temperatures than that of two-row coils and better air pressure drop performance and a lower cost than that of three-row coils (table 2).
| Table 2. Two-Row LWT Coil Performance |
 |
Wondering if LWT Coils are right for your project? Price’s project and application engineers are ready to assist design engineers, building owners, architects and mechanical contractors with product choices that can optimize air distribution system efficiency.
Click here to find a sales representative or technical expert near you, or reach out to our team at airmovement@priceindustries.com.
 |
Mark Mahon is Business Development Manager for Fan Coils and Terminals for Price's Air Moving team. He is based out of Price's Progress facility in Lawrenceville, GA. Click here to connect with him on LinkedIn. |
