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HVAC Systems – What Is A “Design-Day”?

The term “design-day” is used frequently in the HVAC industry, but it can have different meanings and is dependent on many factors. Design-day is typically used to describe a period of time with maximum conditions that a HVAC system was designed to accommodate and maintain the desired indoor temperature and humidity. These conditions can include … Read more

Fan Power Limitations

HVAC engineers balance operating costs versus initial costs in their designs every day. One area where this occurs is ducted air systems and their associated fan motors. An air distribution system could be designed with relatively small ductwork and equipment to keep initial costs lower, but the result is higher static pressures and a higher … Read more

Why Your Freeze Stat Trips

A freeze stat is a sensor located in your HVAC system that is designed to minimize the potential of freezing a water or steam coil in your air distribution system. A true freeze stat is directly interlocked to shut down equipment and requires a manual reset if it trips. This is different than a low temperature sensor … Read more

Electronically Commutated Motors (ECMs)

Electronically commutated motors (ECMs) have quickly become standard in the HVAC industry. They can have unexpected operating characteristics that are very different than their predecessor; the alternating current (AC) permanent split capacitor (PSC) motor. An ECM is a brushless, direct current (DC) motor that operates at a synchronous speed. ECMs utilize integral inverters so they … Read more

Natatorium Corrosion Is A Medley of Factors

Natatoriums are typically the most corrosive environment that facility staff will maintain. The design architect, HVAC engineer, and pool consultant need to reduce the factors that lead to corrosion, but all the designers involved and the facility personnel need to be keenly aware of the cause of natatorium corrosion. The primary drivers of corrosion in the natatorium … Read more

Relative Humidity is “Relative”

Psychrometrics can be a complicated field of study. However, a psychrometric chart can be a simple, invaluable tool to help HVAC engineers and owners understand the relationship between air temperature and humidity.  Relative humidity (RH) is a term that most people are familiar with, but its relationship with dry bulb (DB) temperature is typically under-appreciated.  RH … Read more

High Efficiency Replacement Boilers

As we leave the heating season, many building owners begin repair and replacement projects in their boiler plants. Boilers that burn fuel to heat water have been around for thousands of years and technologies that we would recognize today date back to the early 1700’s. More recent trends in boiler construction and control focus on … Read more

Trends in Chiller Technology

Chillers have been the workhorses of building cooling systems for decades. In recent years, a renewed focus on energy efficiency has led to new and renewed trends in the chiller equipment market such as: Magnetic Bearing Compressors With this breakthrough technology, the compressor impeller shaft is levitated by a magnetic field. The result is a … Read more

Important Changes to the PA Construction Code Act (Act 45) of 1999 | Vol. 2: The 2009 International Mechanical Code (IMC)

The following are some key mechanical code changes that engineers, architects and owners should know about in order to minimize negative impacts to your current or future projects. Section 306.5 Addresses the accessibility of equipment on rooftops and outlines when permanent ladders must be installed to make equipment readily accessible for service. This section states … Read more

Important Changes to the PA Construction Code Act (Act 45) of 1999

Construction codes have been part of our society for thousands of years; and while the purpose of building codes have always been to ensure and maintain our safety, learning and staying current with the codes that affect our industry can be a daunting task. Regardless of how time consuming it may be, taking the time … Read more

Geothermal Heat Pump Systems Part Two – Getting Started With a Formation Thermal Conductivity Test

After reading part one in our series on geothermal heat pump systems, you should be better prepared to decide if this type of system is right for your facility. The next step is to understand how to get started with designing the system. If you determined that a geothermal heat pump system is right for … Read more