Nailor Airwaves is your source for content on relevant topics concerning Nailor Industries, Inc. and the HVAC industry. New product releases, case studies, product & project spotlights, employee interviews, trade publication articles, and general announcements are some of the content types you can expect to find in the Nailor Airwaves.
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Ventilation Strategies: Chilled Beams vs. Chilled Water Fan Powered Terminal Units
A large portion of the energy exerted by an HVAC system comes from conditioning the outside air required by the mechanical code, which typically reference the ASHRAE 62.1 standard. Increasingly, this is performed separately from the building HVAC system by a Dedicated Outside Air System (DOAS). When designing a DOAS system, one decision is how to distribute the air to the space. In my previous Ventilation Strategies article, I highlight a few methods for ventilation distribution. One method I didn't address in the article was Chilled Beams. Chilled Beams compete with the Chilled Water Fan Powered Terminal Unit as a tool for distributing the ventilation from a DOAS. Understanding how each of these tools work, their limitations, and the considerations for selection will help you… Read more
Ventilation Strategies: Controlling Fresh Air
The first goal when designing an HVAC system is occupant comfort. Comfort includes considering thermal, acoustic (sound), and health conditions delivered by the system. HVAC helps create a healthy environment that is achieved through the delivery of fresh air to the space.
ASHRAE Standard
Recognized as a need in the 1960s, ASHRAE documented this with the first publication of standard 62 in 1973. This standard, now known as 62.1, provides the ventilation requirements and guidelines to achieve a well-ventilated building based on occupancy type. The highlight of 62.1 is the ventilation rate calculation procedures located in Section 6. The primary calculation method includes a per person (Rp) and per area (Ra) ventilation requirement for different occupancies. For example, an office space… Read more
VAV Systems: How Air Flows Through the Equipment
The purpose of using a Variable Air Volume (VAV) system is to add controllability to a diversity of occupancies using only one air handling unit. A constant volume system is like what you have in your home, either off or on. If you apply a constant volume system to a space with multiple heating/cooling load profiles, someone will not be comfortable at different times of operation. The fundamental parts of a VAV system include:
Air handling unit
Primary ductwork
Terminal unit
The ductwork/air distribution that serves each zone
Each of these works to deliver the right amount of air to a space to control the desired temperature. More details on these components are in my VAV System Components article. It is critical to understand how the air flows through the components of a VAV system and… Read more
HVAC Ins & Outs with Dan Int-Hout - Area Factors and Free Area
Every so often, we get a request for the Ak, or area factors, or for the “Free Area” for our air outlets and inlets. For many years, manufacturers published “area factors” for balancing purposes. These Ak factors are determined by measurement of indicated air velocities and measured air quantities and can be used to balance HVAC systems. For a number of reasons, these values, however, are no longer being presented. When we get these requests, the first question we must ask is “What are you going to do with the value”?
The Ak value is reported as a constant, reflecting the ratio of sensed discharge velocity to the measured air quantity. It is not based on any physical dimensional relationships. Rather, it is dependent on the type of device used to measure the discharge velocity, as well as… Read more
VAV Control: Terminal Unit Sequence Affects the Entire HVAC System
Developing real estate requires millions of decisions about what the building will look like, how to fit it within a budget, how will it operate, what HVAC system to use, etc., etc., etc. Each decision has an impact on the final product. One of these small decisions may never be consciously by the engineer designing the mechanical systems. As a junior engineer straight out of college, I was designing mechanical systems as a consulting engineer. This involved listening to the client, performing load calculations, and choosing the equipment to keep the occupants comfortable. One of the last parts of this was to import a drawing, "specs.dwg", into the drawing package that contained all the specifications for the mechanical drawings. This drawing had every spec for all equipment the firm… Read more