Tuesday, January 31, 2017: 2:45 PM-3:45 PM
Building Operation and Performance
Chair: Constantinos A. Balaras, Ph.D., Institute for Environmental Research & Sustainable Development, NOA
Technical Committee: 6.5 Radiant Heating and Cooling
Sponsor: Residential Building Committee
CoSponsor: 6.1 Hydronic and Steam Equipment and Systems
In the land of comfort, educated home owners are changing their thermal expectations from HVAC systems, and contractors are on the front line hunting for the best solutions. Regardless of ducts or pipes, the “migration” of heat takes a basic understanding of what works and what doesn’t. It is not easy to figure out the right design for the application, especially as homes get more efficient. Low-cost ducted systems may not always work right or be the best fit. This seminar looks at best practices for distributing heat in residential air and hydronic systems, including ducted and radiant design options.
1 Flex Duct Doesn't Mean You Can Flex the Rules
This presentation shines the light of truth on airflow in poorly installed residential flexible ducts. Advertised airflow data is based on ASHRAE Standard 120 testing, which is a valid test protocol, but not reflective of actual performance in field installed flexible ducts. A new ASHRAE Duct Size Calculator (now available from ASHRAE Publications) is also described.
2 Hard Ducts Are Not so Hard
Before flex duct showed up on the scene, rigid sheet metal ducts dominated forced air distribution systems. Hard-pipe systems aren’t as common now, but they’re still effective and useful. They can be more durable and efficient than flex and fiberglass ductboard when designed and installed properly. Presented are some best practices to follow when designing, installing, and commissioning hard-pipe ducts systems.
3 What Ducts? Who Needs Ducts?
This presentation focuses on hydronics, the original ductless systems as alternatives to ducted systems in residential applications. It provides an overview of converting sensible cooling and heating loads into flow rates, how and why to pick pipes based on velocity and head loss; and how to best distribute the flows to enable occupants to sense and perceive thermal comfort without ductwork.