St. Louis, MO, United States
St. Louis, MO, United States

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Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2015

A common perception is that a reverse-return hydronic piping configuration uses more piping and, therefore, is more expensive than its direct-return counterpart. For example, a hydronics primer recently published in ASHRAE Journal briefly discusses direct versus reverse-return piping arrangements and quickly reaches that conclusion. While the cost disadvantage of reverse-return is true in some instances, this column presents a case that reverse-return doesn't always add piping length and system cost, depending on system configuration. In addition, this author has found reverse-return is sometimes overlooked or dismissed out-of-hand when it offers tangible benefits and could easily have been implemented at no net cost to the project. So, a goal of this column is to encourage pipe system designers to explore and consider reverse-return in further detail. Copyright 2015 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Transactions | Year: 2012

An article published in the December 2009 ASHRAE Journal suggested that a detailed modeling analysis, in lieu of a single-number such as IPLV per AHRI Standard 550/590-2003, should be used to make purchasing decisions for chillers, especially in multi-chiller applications. Detractors claim that an hourly modeling analysis is too cumbersome, whereas IPL V is easy. In this paper, a consulting engineer presents examples of an easy-to-use modeling method that is more true-to-life than IPL V for multi-chiller plant energy evaluations based on life cycle cost, for comparison of chiller purchasing options. © 2012 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2015

Building system design engineers have many opportunities to hone their expertise in HVAC design throughout their career. However, many are called upon to design and specify mechanical systems related to fuel oil only occasionally. Those who design HVAC building systems on a near-daily basis will be assigned to design and specify the mechanical auxiliaries for engine generators or oil-fired boilers by those who assume that their expertise automatically extends to "anything mechanical." Some skills carry over well, but there are many facets of fuel oil system design that an experienced HVAC engineer will not necessarily be familiar with. Copyright 2015 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2015

In my most recent Engineer's Notebook column four months ago,1 I gave a review of three important safety-oriented code requirements that tend to be overlooked in mechanical design. Reaction to that column was favorable, and I am still admittedly on my code soapbox, so I offer several more code requirements similarly overlooked. These are also critical safety- or service-related features applicable to building mechanical systems: code requirements that are frequently overlooked by engineers, design-build specialists, contractors, and even code officials. These are all real examples from actual facilities upon which I have performed property condition assessments, peer reviews I performed of designs by others, or retrofit of designs by others. Copyright © 2015 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2014

The Fire and Smoke Damper Summary for HVAC engineers and designers based on the 2012 International Building Code is discussed. It is important to learn the differences between a fire wall, fire barrier, and fire partition and between a smoke barrier and smoke partition, so that we can properly apply (or not apply) fire and smoke dampers. No dampers are required in ducted penetrations of smoke partitions, including those in hospital corridor walls. One should not put any dampers in Type 1 grease exhaust and clothes dryer exhaust systems. If a fire or smoke damper placement will interfere with the operation of an engineered smoke exhaust system, approved alternate protection shall be used. Frame A means the blades, in the open position, partially block the free area of the duct. Frame B means the blades, in the open position, are completely outside the free area of the duct. Frame C is for round ducts. These frame types apply only to curtain-type fire dampers, not to multi-blade type dampers like most combination fire/smoke dampers. Fire dampers and smoke dampers must be accessible for service. If reaching inside the duct is necessary then we must provide a duct access door and a ceiling access panel or an accessible ceiling type.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2014

Three code requirements that are sometimes overlooked in mechanical design are presented here. Each topic is derived from the author's own experiences found many times while performing property condition assessments or peer reviews of other designs in actual facilities. This column is intended to be used as a summary checklist or a quick reference guide for HVAC design professionals, to avoid repeating these oversights on future building projects. Copyright 2014 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2016

One challenge I like to pose to younger consulting engineers is to explain to me how a simple air-conditioning unit works, at its most basic, fundamental level. Usually, the responses I get include a lot of college textbook jargon such as "well, there is an isentropic process in the compressor which⋯" or some version of the perfect gas law with regard to the refrigerant, or a discussion of the Reverse Carnot Cycle. I stop them. And, I ask them to tell me in simple layperson's terms what is the process in an air conditioner that makes air cold. That skill is important because it confirms whether they truly understand how it works, and it enables them to explain the process to non-technical clients in the future.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Transactions | Year: 2011

Multi-evaporator split air-conditioning systems, especially Variable Refrigerant Flow (VRF) systems, are receiving increased attention in the marketplace, as an alternative to water-source heat pump loops, hydronic fan-coil networks, room-by-room packaged terminal units, and even all-air systems. These systems are sometimes characterized by a significant amount of field refrigerant piping, a large number of evaporators on a common refrigerant pipe network with one condensing unit, and safety concerns related to the potential for refrigerant leaks. This paper examines the consequences and safety-based limitations imposed on such systems by ANSI/ASHRAE Standard 15-2010, explores some ambiguity not specifically covered by the Standard, attempts to assist the system design engineer on proper application of the Standard, and identifies areas where further study or research is needed to provide sound guidance on the safe application of these systems. © 2011 ASHRAE.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Journal | Year: 2016

In my last column for the "Engineer's Notebook" series,I pointed out that building system design engineers who regularly design comfort heating and cooling systems may be called upon only occasionally to design and specify mechanical systems related to emergency power generation. There may be some facets of engine generator system design with which an experienced HVAC engineer will not necessarily be familiar. That previous column dealt with the fuel oil systems; this column will attempt to tackle engine cooling and generator room ventilation.


Duda S.W.,Ross and Baruzzini Inc.
ASHRAE Transactions | Year: 2012

ASHRAE is strongly emphasizing the need for sustainable or low-energy design practice through programs, papers, standards, the Advanced Energy Design Guide series, and the Net-Zero Energy Building initiative. The author of this paper does not dispute the urgent need for energy-conscious design. However, low-energy mechanical equipment and systems are sometimes more costly to purchase and install than their more traditional counterparts. In many areas of the Midwestern United States, low utility rate structures are available, in some cases as low as $0.04 per kilowatt-hour for electricity. These utility rates tempt building owners and decision-makers to forego more expensive but lower-energy HVAC options due to lack of an attractive return on investment. This paper explores the conundrum experienced by responsible engineers in attempting low-energy design where very low utility costs drive financial decisions in the opposite direction. Included are examples from ASHRAE 's "50% Advanced Energy Design Guide for Small to Medium Office Buildings." ©2012 ASHRAE.

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