TSI Alnor EBT731, EBT730 User Manual

HVAC

ASSESSMENT

HANDBOOK

A PRACTICAL GUIDE TO PERFORMANCE
MEASUREMENTS IN MECHANICAL HEATING,
VENTILATING, AND AIR CONDITIONING SYSTEMS

UNDERSTANDING, ACCELERATED

HVAC

ASSESSMENT HANDBOOK

A PRACTICAL GUIDE TO PERFORMANCE

MEASUREMENTS IN MECHANICAL HEATING,

VENTILATING, AND AIR CONDITIONING SYSTEMS

_____________________
TSI, TSI logo, Alnor, VelcoiCalc and AccuBalance are registered trademarks of TSI Incorporated.
IAQ-Calc, DP-Calc, TrakPro, LogDat2, and Airflow Instruments are trademarks of TSI Incorporated.

Copyright © 2013 by TSI Incorporated

Contents

Introduction ............................................................................................................................................................ 1

Building Design and Operation .......................................................................................................................................... 1

Efficiency vs. Effectiveness ................................................................................................................................................... 2

Special Considerations ........................................................................................................................................................... 2

Indoor Air Quality .................................................................................................................................................................... 3

Outdoor Air ................................................................................................................................................................................. 3

Key Performance Measurements ...................................................................................................................................... 4

What – Air handling equipment ................................................................................................................................... 4

What – Air velocity ............................................................................................................................................................. 5

What – Ventilation ............................................................................................................................................................. 6

What – Air volume and number of changes ............................................................................................................ 7

What – Thermal Comfort ................................................................................................................................................ 9

What – Airborne contaminants as related to Indoor Air Quality (IAQ) .................................................. 10

What – Differential Pressure ...................................................................................................................................... 11

What – System Pressure ............................................................................................................................................... 12

What – Air Filters ............................................................................................................................................................. 14

Conclusion ................................................................................................................................................................................ 16

Sources for Information Relating to Managing Mechanical HVAC Systems .................................... 17

Standards and Guidelines ................................................................................................................................. 18

National Ambient Air Quality Standards..................................................................................................................... 18

Air Quality Guidelines ......................................................................................................................................................... 19

Glossary .................................................................................................................................................................. 20

Typical Mechanical Ventilation System ....................................................................................................................... 21

VTI Instruments from TSI ................................................................................................................................. 22

Notes ........................................................................................................................................................................ 27

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HVAC Assessment Handbook

Some basic considerations to address when
specifying the equipment needed to control and
condition the air should include the size and
physical layout of the building, which
determines equipment requirements such as
the size and type of fans, boilers, coils and
filters. A thorough understanding of the entire
system, from the outdoor air intake to the
furthest diffuser is essential to good system
design. It is also important to understand the
specific purpose of the space and activities
taking place. This will greatly influence the

INTRODUCTION

Heating, Ventilating, and Air Conditioning (HVAC) relates to systems that perform processes

designed to regulate the air conditions within buildings for the comfort and safety of occupants or
for commercial and industrial processes or for storage of goods. HVAC systems condition and
move air to desired areas of an indoor environment to create and maintain desirable
temperature, humidity, ventilation and air purity.

Depending on geographic location and building construction, various types of interior climate
control systems help ensure that interior spaces are maintained at comfortable levels year-round.
With today’s energy conservation concerns, buildings are constructed to be much tighter,
reducing the level of natural exchange between indoor and outdoor air. As a result, more and
more buildings rely on mechanical conditioning and distribution systems for managing air.

A properly operated HVAC system finds the often-delicate balance between optimizing occupant
comfort while controlling operating costs. Comfort is an important issue for occupant satisfaction,
which can directly affect concentration and productivity. At the same time, controlling these
comfort and health parameters directly affects HVAC system operating costs in terms of energy,
maintenance and equipment life.

This handbook is not intended to be a comprehensive guide for all possible issues associated with
HVAC system operation and maintenance. There are volumes on the subject. Rather, it highlights
some measurements and techniques that can be used to evaluate HVAC systems for optimum
operation.

Building Design and Operation

building’s conditioning requirements. This further dictates appropriate equipment and the
capacity needed to meet those requirements. Design parameters must account for cooling load,
heating load, ventilation and filtration requirements. Other considerations that directly impact
the HVAC system include the number of people in each space, interior elements like wall
placements, furnishings and equipment that may create barriers to impede airflow and
distribution. Internal loads such as lights, computers and other equipment that may produce heat,
humidity or otherwise affect ambient air conditions must also be considered.

The design of air distribution equipment in today’s buildings presents challenges for the

mechanical engineer. Equipment selection must combine properly engineered products, which
efficiently provide conditioned air to the occupied space while blending in with the architectural
features of the interior. Considerable time and money can be spent developing and purchasing the
appropriate mechanical components, system controls, ductwork and piping. If components are
selected improperly, the HVAC system will operate inefficiently, not meet requirements and
create cost overruns to correct the situation. Since one aspect of the system affects another,
proper selection of every component, regardless of apparent significance, is imperative.

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HVAC Assessment Handbook

Some situations require special attention with respect to
the HVAC system. This section lists a few examples from
the many situations where HVAC systems play a key role
in success or failure.

Some applications have strict requirements for precise
temperature and humidity control. These include food
processing, storage of perishables, certain industrial
processes, chemical processing and storage, computer
rooms, green houses and other applications where a few
degrees difference in temperature could mean the ruin
of costly product or equipment.

Efficiency vs. Effectiveness

With any mechanical ventilation system, there is a trade-off between optimizing occupant
comfort and controlling operating costs. Common measurements for assessing effectiveness or
the level of comfort among occupants include a variety of parameters such as temperature,
humidity, air velocity, ventilation, vibration and noise. Individual perception plays a significant
role since comfort is both physical and psychological and can vary greatly by individual. What is
comfortable for one person may be too warm for the next and too cool for a third.

When maximizing the operating efficiency of a system, a number of factors must be considered
including fuel source and cost, electrical consumption, air filtration, equipment life, maintenance
costs and more. These expenditures are often very visible. Controlling them has a direct impact on
the day-to-day cost of building operation and can impact a company’s profitability. Reducing
HVAC operating expenditures to a point where occupants are dissatisfied has other costs
associated with it, including increased costs due to absenteeism, loss of people due to employee
turnover, recruiting, training and decreased productivity to name but a few. So it is important to
balance comfort against cost so both are optimized.

Special Considerations

In some laboratories and health care facilities, the potential for the migration of dangerous or
infectious substances is a concern. Patients recovering from surgery, transplants or other immune
compromised conditions are especially prone to airborne infections and may require special
consideration with respect to filtration and ventilation. (TSI has published a brochure featuring
instrumentation for managing differential pressure in health care facilities. Visit our website at

www.tsi.com to view the brochure).

Cleanrooms in the semiconductor industry require very stringent filtration and control of
ambient air. Here, even a small breach in contamination control could mean the loss of a
considerable amount of valuable product.

Many buildings have adjacent or underground parking areas and controlling the introduction of
vehicle emissions into the building is imperative. Smoking restrictions have been implemented in
public buildings, restaurants and many corporate facilities. In general, proper exhaust and
ventilation is an important concern to rid the building of unwanted contaminants.

During construction or renovation, special attention must be paid to the HVAC system to contain
and control unwanted airborne contamination and prevent it from migrating to other areas of a
building. Maintaining negative relative pressure in the construction area is an important
consideration along with special filtration and, perhaps, dedicated exhaust.

Another matter regarding our national interest is protecting buildings from the infiltration of
dangerous material, particularly airborne nuclear, biological or chemical (NBC) agents. Here
special consideration must be given to controlling and protecting the outdoor air intake, filtration,

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HVAC Assessment Handbook

An issue that is frequently overlooked and ends up being
dealt with after the fact is the impact of the surrounding
environment on a building. Too often, aesthetic consideration
places outdoor air intakes in areas of the building that may
be exposed to all sorts of problems. The quality of the indoor
air will be affected if an intake is facing heavy traffic,
industrial discharges, or other sources of unwanted
pollutants. Such situations may require special filtration,
could lead to premature loading of filters, increased
maintenance and cleaning costs and unexpected wear and
tear on the equipment. Corrective action may involve
upgrading to more effective filters or, in extreme cases,
relocating the outdoor air intake.

The EPA enacted the National Ambient Air Quality Standards
in reaction to the Clean Air Act passed in 1970. The Clean Air
Act established two types of national air quality standards.

the level of uncontrolled leakage and the ability of the system to purge a building. Mechanical
ventilation systems have various controls to regulate air flow and pressure in a building that can
be essential in an emergency response situation. In some cases, with sufficient time, it may be

wise to shut off the building’s HVAC and exhaust system to help prevent the introduction of NBC

agents. Other times, the system can be used to regulate pressure and airflow to control the
migration or spread of unwanted agents through the building. Special training for building
personnel may be required for them to recognize situations requiring certain action and be
familiar with the proper plan of action.

Indoor Air Quality

Indoor air quality (IAQ) is a growing concern today. Concern with energy conservation has made
building construction nearly airtight, which, in turn, has made proper ventilation more important
than ever. People today are spending the majority of their lives indoors, more than 90% of the
time according to the EPA. Managing indoor air quality can have a big impact on the satisfaction,
productivity and health of occupants. Three general categories of contaminants can impact IAQ:
biological, chemical and particle related pollutants. The key to effective IAQ management is
finding and controlling the exact source of the contamination. It is not acceptable to treat
symptoms. The problems will not go away until the source is removed, repaired or controlled so
that creation and migration of unwanted pollutants is completely arrested.

TSI has published a practical guide to address some of the key issues in IAQ management today. It
can be viewed on the TSI web site at http://iaq.tsi.com.

Outdoor Air

Primary standards set limits to protect public health, including the health of "sensitive"

populations such as asthmatics, children, and the elderly. Secondary standards set limits to
protect public welfare, including protection against decreased visibility, damage to animals, crops,
vegetation, and buildings. The Clean Air Act requires the EPA to set National Ambient Air Quality
Standards (NAAQS) (see table on page 18) for pollutants considered harmful to public health and
the environment. The NAAQS is instrumental in providing guidelines for the location of outdoor
air intakes.

The EPA Office of Air Quality Planning and Standards (OAQPS) has set National Ambient Air
Quality Standards for seven principal pollutants, which are called "criteria" pollutants. They are
listed in the table on page 18, near the end of this book.

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HVAC Assessment Handbook

then distributed through a network of ducts to and from areas of
the building. Basic components include dampers, fans or
blowers, heating and cooling coils, air filters, boilers or furnaces,
compressors, ductwork to convey the air and diffusers or
registers to distribute the air evenly. A number of controlling
mechanisms, including thermostats, sensors and actuators, help
control the distribution of air throughout a building.

Routine preventative maintenance is the key to avoiding
premature wear and tear on components that can lead to repair
or premature replacement. Repair and replacement can be costly
and often lead to inconvenient, even unacceptable downtime.
There are situations, such as in hospitals, where unexpected

Key Performance Measurements

What – Air handling equipment

The following are some examples of the many different types of HVAC systems available today.

Single-zone system—serves a single, temperature-controlled zone. Found in small shops or
computer rooms where the environment and usage generally remains the same.

Multi-zone system—delivers conditioned air to several zones from a single, central air-handling
unit. The zones served should have similar thermal load requirements such as offices or
classrooms. Conditions in each space are maintained by temperature controllers in each zone,
which vary the amount of heated or cooled air to be delivered.

Constant volume system—the volume of air delivered to an occupied zone by this system does
not change, or changes very little. The discharge temperature is controlled in the zone by a
temperature controller, which activates heating and/or cooling coils.

VAV (Variable Air Volume) system—air volume to a zone is adjusted via a damper that
responds to a zone thermostat controlling heating and cooling coils. VAV boxes can be found on
multi-zone system duct runs that are new to the building or are a considerable distance away
from the central air handler unit.

Heat pumps—a type of refrigeration system that draws out heated indoor air in the warm
weather to keep the occupied space cool, and removes heat from the outdoor air and transfers it
to the inside during cold weather periods.

Unit ventilator—a single, self-contained system found in hotel/motel rooms, schools, garages,
and other applications where individual room environments must be maintained separately.

Why

The HVAC system can be viewed as the cardiovascular and respiratory system of a building,
supplying clean conditioned air to all areas. The air handler is the heart of the system since this is
where outdoor air is drawn in, filtered, conditioned and mixed with return air. This “supply” air is

system downtime is simply not an option for a 24/7 operation. Therefore, it is critical to be aware

of the system’s condition and components, to perform routine cleaning and do minor repairs. This

will extend equipment life and allow for major repair or replacement to be scheduled at a time

when it has less impact on disrupting business. Over time, “dirt” can lead to the demise of an

HVAC system. At a minimum, unwanted contaminants can inflict damage to equipment that leads
to premature wear and tear, increased maintenance costs, increased cleaning costs and lower
operating efficiency.

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HVAC Assessment Handbook

Why

Fans are used to introduce, distribute, recirculate and
exhaust air in a building. Checking air velocity
periodically at various points assures that air is being
distributed as expected through the ventilation system.
Measurements should be made on both the supply and
return air sides of the system. Air movement or velocity
has an impact on perceived comfort by occupants.

When

Regular “spot” checks should be performed in different

locations throughout the building to be sure that the
system is performing as expected. Special attention

When

It is recommended that a regular, routine schedule be established for checking system
components. Some items may need inspection more often than others, so establish a procedure
that indicates when each element should be checked. Periodic inspection of components is critical
to identify and remedy potential problems at the earliest stage when corrective action can be
done in less time and usually at considerably less expense than waiting until failure occurs.

Where

Most of these inspections must be made directly inside the air handler and ductwork. Air handlers
often have access doors for performing inspections, service, repair or replacement. Other areas of
the air handler and ducts are often equipped with small access holes for inspection and taking
duct traverse measurements. These holes are re-sealed with a small plastic plug, which can be
removed for future measurements.

How

Outdoor air is introduced to the air handler through an inlet vent that is typically controlled with
a damper, either manually or mechanically operated. This outdoor air is mixed with the return
air, and this mixed air passes through an air filter. The filtered air may then be conditioned by
heating coils, cooling coils, moisture reduction devices, and humidifiers. The conditioned air is
then passed through a final filter and delivered via ductwork to all the zones of the building.
Damper positioning sensors, temperature controls, volume flow and humidity controls are some
of the measurement parameters that should be continuously monitored to give an indication of
system performance or to signal alarms if any control aspect is outside of acceptable limits. Fan
belt tension, clogged drain pans, dirty heating/cooling coils and fan blades, misaligned filters, and
other mechanical components may require visual inspections, performed on a periodic basis.

Economic implication—too often, the ventilation system is taken for granted until some sort of
mishap occurs. Unforeseen, preventable problems can have serious consequences, including work
stoppage, spoiled inventory, and unexpected equipment service or replacement costs. Many of
these problems can be prevented by implementing and following scheduled maintenance tasks.

What – Air velocity

should be paid whenever something in the building changes that may impact the HVAC system’s

performance. Examples include switching over from heating to cooling, remodeling, rearranging a
space, enlarging or reducing the area being served and adding or subtracting people.

Where

Air velocity measurements should be made at diffusers or registers both on the supply and return
sides of the system. Measurements should be made in the ductwork, paying particular attention
to sections close to dampers, transitions, elbows, branches and take-offs to be sure air is moving
as expected throughout the system and that nothing is impeding air movement. For highest
accuracy, measurements should be made in a straight section of duct roughly the equivalent of

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