Ashrae 1999 HVAC Applications Handbook.pdf

1999 ASHRAE Handbook Preface

This handbook describes heating, ventilating, and air condition-

ing for a broad range of applications. Most of the chapters from the

1995 ASHRAE Handbook have been revised for this volume to

reflect current requirements and design approaches. New chapters

on HVAC for museums and power plants, information on air quality

in aircraft, additional information on maintaining a proper environ-

ment for indoor swimming pools and new information on sound

control and building operation make this a particularly useful refer-

ence. Because this book focuses on specific applications for HVAC,

it provides background information to designers new to the applica-

tion as well as to those needing a refresher on the topic. In addition,

many chapters include valuable data for design. Some of the revi-

sions that have been made are as follows.

• Chapter 4, Places of Assembly, provides more comprehensive

design information on natatoriums.

• Chapter 5, Hotels, Motels, and Dormitories, includes more infor-

mation on hotels and motels, which is reflected in a change in the

title of the chapter.

• Chapter 8, Surface Transportation, has been substantially revised.

It now includes information about European bus air conditioning

and the state of the art in railcar air conditioning.

• Chapter 9, Aircraft, has been completely rewritten. It describes

the environmental control systems used in commercial aircraft

today and their operation during a typical flight. Applicable reg-

ulations are summarized and the section on air quality has been

expanded. Information on air-cycle equipment has been deleted.

• Chapter 12, Enclosed Vehicular Facilities, includes more ventila-

tion design information. Research from a tunnel fire test has pro-

vided new ventilation design criteria for tunnel ventilation. The

chapter now covers ventilation for toll booths, railroad tunnels,

and areas with vehicles that use alternative fuels.

• Chapter 13, Laboratories, has additional information on scale-up

laboratories and compressed gas storage. The sections on internal

heat load and Biosafety Level 3 have been expanded.

• Chapter 15, Clean Spaces, greatly expands on pharmaceutical and

biomanufacturing cleanrooms. A new section covers high bay

cleanrooms.

• Chapter 20, Museums, Libraries, and Archives, is a new chapter.

It discusses in detail the importance of relative humidity on col-

lections and suggests the degree of environmental control for var-

ious types of collections and historic buildings.

• Chapter 21, Environmental Control for Animals and Plants, pro-

vides new information on levels of contaminants in livestock

buildings and suggests several methods of control. It includes

new findings on ventilation for laboratory animals.

• Chapter 24, Power Plants, is a new chapter that introduces HVAC

design criteria for the various facilities in electrical generating

stations and in facilities that produce process heat and power.

• Chapter 29, Industrial Local Exhaust Systems, has been greatly

expanded with much more information about specific types of

hoods and their design and application.

• Chapter 30, Kitchen Ventilation, is updated to reflect code

changes including changed terminology for nonlisted hoods and

new information on exhaust system effluent control.

• Chapter 33, Thermal Storage, has an expanded discussion of con-

trol strategies.

• Chapter 34, Energy Management, has new and more comprehen-

sive energy consumption data for commercial and residential

buildings in the United States.

• Chapter 35, Owning and Operating Costs, has updated informa-

tion of the impact of refrigerant phaseouts. New information is

included on financing alternatives, on district energy service and

on-site electric generation in view of deregulation, and on com-

puter analysis.

• Chapter 39, Building Energy Monitoring, reflects the new direc-

tion in this field and focuses on monitoring designed to answer

specific questions rather than broad-based research-oriented pro-

grams. The section on accuracy and uncertainty is rewritten.

• Chapter 40, Supervisory Control Strategies and Optimization, has

a new title to reflect its reorganization and the significant amount

of new material. The first section defines systems and control

variables. The second section, which is intended for practitioners,

presents computerized control strategies. The third section pre-

sents basic optimization methods and is for researchers and devel-

opers of advanced control strategies.

• Chapter 41, Building Commissioning, has expanded the informa-

tion on the various phases of commissioning.

• Chapter 42, Building Envelopes, is moved from the 1997

ASHRAE Handbook—Fundamentals with minor editing.

• Chapter 43, Building Air Intake and Exhaust Design, is a revision

of the last half of Chapter 15 in the 1997 ASHRAE Handbook .

• Chapter 44, Control of Gaseous Indoor Air Contaminants, has

a greatly expanded section on air cleaning. It includes more

information on the equipment used and on its design, energy

use, startup procedures, operation, maintenance, and testing

procedures.

• Chapter 45, Design and Application of Controls, is slightly reor-

ganized because the information on control fundamentals was

moved to the 1997 ASHRAE Handbook .

• Chapter 46, Sound and Vibration Control, describes all currently

recognized criteria methods—dBA, NC, RC, RC Mark II, and

NCB. New sections include information on: (1) uncertainties that

can reasonably be expected from the data in the chapter, (2)

chiller and air-cooled condenser noise, and (3) data for estimating

ceiling plenum insertion loss.

• Chapter 47, Water Treatment, is reorganized and has added infor-

mation on biological growth control. A new section covers start-

up and shutdown procedures.

• Chapter 49, Snow Melting, includes expanded equations for

heating requirements and new load data including maps. Infor-

mation on piping materials for hydronic systems has been

updated.

• Chapter 51, Fire and Smoke Management, includes new sections

on fire management (i.e., through-penetration fire stopping) and

on smoke management in large spaces.

• Chapter 53, Seismic and Wind Restraint Design, introduces the

proposed International Building Code seismic design equations

and describes several new seismic snubbers. The chapter also

includes a new section on wind restraint design.

Each Handbook is published in two editions. One edition con-

tains inch-pound (I-P) units of measurement, and the other contains

the International System of Units (SI).

Look for corrections to the 1996, 1997, and 1998 volumes of the

Handbook on the Internet at http://www.ashrae.org. Any changes to

this volume will be reported in the 2000 ASHRAE Handbook and on

the Internet.

If you have suggestions for improving a chapter or you would

like more information on how you can help revise a chapter, e-mail

bparsons@ashrae.org; write to Handbook Editor, ASHRAE, 1791

Tullie Circle, Atlanta, GA 30329; or fax (404) 321-5478.

Robert A. Parsons

ASHRAE Handbook Editor

CHAPTER 1

RESIDENCES

Single-Family Residences .............................................................................................................. 1.2

Multifamily Residences .................................................................................................................. 1.5

Manufactured Homes ..................................................................................................................... 1.6

S both local and application factors. Local factors include energy

source availability (both present and projected) and price; climate;

socioeconomic circumstances; and the availability of installation

and maintenance skills. Application factors include housing type,

construction characteristics, and building codes. As a result, many

different systems are selected to provide combinations of heating,

cooling, humidification, dehumidification, and air filtering. This

chapter emphasizes the more common systems for space condition-

ing of both single-family (i.e., traditional site-built and modular or

manufactured homes) and multifamily residences. Low-rise multi-

family buildings generally follow single-family practice because

constraints favor compact designs. Retrofit and remodeling con-

struction also adopt the same systems as those for new construction,

but site-specific circumstances may call for unique designs.

An optional humidifier (10) adds moisture to the heated air, which

is distributed throughout the home from the supply duct (9). When

cooling is required, the circulating air passes across the evaporator

coil (5), which removes heat and moisture from the air. Refrigerant

lines (6) connect the evaporator coil to a remote condensing unit (7)

located outdoors. Condensate from the evaporator is removed

through a drainline with a trap (8).

Figure 2 shows a split-system heat pump, supplemental electric

resistance heaters, a humidifier, and an air filter. The system func-

tions as follows: Air returns to the equipment through the return air

duct (1) and passes through the air filter (2). The circulating blower

(3) is an integral part of the indoor unit (or air handler) of the heat

pump (4), which supplies heat via the indoor coil (6) during the

heating season. Optional electric heaters (5) supplement heat from

the heat pump during periods of low ambient temperature and coun-

teract airstream cooling during the defrost cycle. An optional

humidifier (10) adds moisture to the heated air, which is distributed

throughout the home from the supply duct (9). When cooling is

required, the circulating air passes across the indoor coil (6), which

removes heat and moisture from the air. Refrigerant lines (11) con-

nect the indoor coil to the outdoor unit (7). Condensate from the

indoor coil drains away through a drainline with a trap (8).

Systems

The common residential heating systems are listed in Table 1.

Three generally recognized groups are central forced air, central

hydronic, and zoned systems. System selection and design involve

such key decisions as (1) source(s) of energy, (2) means of distribu-

tion and delivery, and (3) terminal device(s).

Climate determines the services needed. Heating and cooling are

generally required. Air cleaning (by filtration or electrostatic

devices) can be added to most systems. Humidification, which can

also be added to most systems, is generally provided in heating sys-

tems only when psychrometric conditions make it necessary for

comfort and health (as defined in ASHRAE Standard 55). Cooling

systems dehumidify as well. Typical residential installations are

shown in Figures 1 and 2.

Figure 1 shows a gas furnace, a split-system air conditioner, a

humidifier, and an air filter. The system functions as follows: Air

returns to the equipment through a return air duct (1). It passes

initially through the air filter (2). The circulating blower (3) is an

integral part of the furnace (4), which supplies heat during winter.

Table 1 Residential Heating and Cooling Systems

Forced Air

Hydronic

Zoned

Most common

energy sources

Gas

Oil

Electricity

Resistance

Heat pump

Gas

Oil

Electricity

Resistance

Heat pump

Gas

Electricity

Resistance

Heat pump

Heat distribution

medium

Air

Water

Steam

Air

Wa t er

Refrigerant

Heat distribution

system

Ducting

Piping

Ducting

Piping or

None

Terminal devices

Diffusers

Registers

Grilles

Radiators

Radiant panels

Fan-coil units

Included

with

product

The preparation of this chapter is assigned to TC 7.6, Unitary Air Condi-

tioners and Heat Pumps

Fig. 1 Typical Residential Installation of Heating, Cooling,

Humidifying, and Air Filtering System

PACE-CONDITIONING systems for residential use vary with

1.2

1999 ASHRAE Applications Handbook (SI)

Fig. 2 Typical Residential Installation of Heat Pump

designed to meet or exceed the requirements of ASHRAE Standard

90.2, Energy-Efficient Design of New Low-Rise Residential Build-

ings, or similar requirements.

Proper matching of equipment capacity to the design heat loss

and gain is essential. The heating capacity of air-source heat pumps

is usually supplemented by auxiliary heaters, most often of the elec-

tric resistance type; in some cases, however, fossil fuel furnaces or

solar systems are used.

The use of undersized equipment results in an inability to main-

tain indoor design temperatures at outdoor design conditions and

slow recovery from setback or set-up conditions. Grossly oversized

equipment can cause discomfort due to short on-times, wide indoor

temperature swings, and inadequate dehumidification when cool-

ing. Gross oversizing may also contribute to higher energy use due

to an increase in cyclic thermal losses and off-cycle losses. Variable

capacity equipment (heat pumps, air conditioners, and furnaces) can

more closely match building loads over specific ambient tempera-

ture ranges, usually reducing these losses and improving comfort

levels; in the case of heat pumps, supplemental heat needs may also

be reduced.

Recent trends toward tightly constructed buildings with

improved vapor retarders and low infiltration may cause high

indoor humidity conditions and the buildup of indoor air contami-

nants in the space. Air-to-air heat-recovery equipment may be used

to provide tempered ventilation air to tightly constructed houses.

Outdoor air intakes connected to the return duct of central systems

may also be used when lower installed costs are the most important

factor. Simple exhaust systems with passive air intakes are also

becoming popular. In all cases, minimum ventilation rates, as out-

lined in ASHRAE Standard 62 should be maintained.

Single-package systems, where all equipment is contained in one

cabinet, are also popular in the United States. They are used exten-

sively in areas where residences have duct systems in crawlspaces

beneath the main floor and in areas such as the Southwest, where

they are typically rooftop-mounted and connected to an attic duct

system.

Central hydronic heating systems are popular both in Europe and

in parts of North America where central cooling is not normally pro-

vided. If desired, central cooling is often added through a separate

cooling-only system with attic ducting.

Zoned systems are designed to condition only part of a home at

any one time. They may consist of individual room units or central

systems with zoned distribution networks. Multiple central systems

that serve individual floors or serve sleeping and common portions

of a home separately are also widely used in large single-family

houses.

The source of energy is a major consideration in heating system

selection. For heating, gas and electricity are most widely used, fol-

lowed by oil, wood, solar energy, geothermal energy, waste heat,

coal, district thermal energy, and others. Relative prices, safety, and

environmental concerns (both indoor and outdoor) are further fac-

tors in heating energy source selection. Where various sources are

available, economics strongly influence the selection. Electricity is

the dominant energy source for cooling.

SINGLE-FAMILY RESIDENCES

Heat Pumps

Heat pumps for single-family houses are normally unitary sys-

tems; i.e., they consist of single-package units or two or more fac-

tory-built modules as illustrated in Figure 2. These differ from

applied or built-up heat pumps, which require field engineering to

select compatible components for complete systems.

Most commercially available heat pumps (particularly in North

America) are electrically powered air-source systems. Supplemen-

tal heat is generally required at low outdoor temperatures or during

defrost. In most cases, supplemental or backup heat is provided by

electric resistance heaters.

Heat pumps may be classified by thermal source and distribution

medium in the heating mode as well as the type of fuel used. The

most commonly used classes of heat pump equipment are air-to-air

and water-to-air. Air-to-water and water-to-water types are also

used.

Heat pump systems, as contrasted to the actual heat pump equip-

ment, are generally described as air-source or ground-source. The

thermal sink for cooling is generally assumed to be the same as the

thermal source for heating. Air-source systems using ambient air as

the heat source/sink are generally the least costly to install and thus

the most commonly used. Ground-source systems usually employ

water-to-air heat pumps to extract heat from the ground via ground-

water or a buried heat exchanger.

Ground-Source (Geothermal) Systems. As a heat source/sink,

groundwater (from individual wells or supplied as a utility from

community wells) offers the following advantages over ambient

air: (1) heat pump capacity is independent of ambient air tempera-

ture, reducing supplementary heating requirements; (2) no defrost

cycle is required; (3) for equal equipment rating point efficiency,

the seasonal efficiency is usually higher for heating and for cooling;

and (4) peak heating energy consumption is usually lower. Ground-

coupled or surface-water-coupled systems offer the same advan-

tages. However, they circulate brine or water in a buried or sub-

Equipment Sizing

The heat loss and gain of each conditioned room and of ductwork

or piping run through unconditioned spaces in the structure must be

accurately calculated in order to select equipment with the proper

output and design. To determine heat loss and gain accurately, the

floor plan and construction details must be known. The plan should

include information on wall, ceiling, and floor construction as well

as the type and thickness of insulation. Window design and exterior

door details are also needed. With this information, heat loss and

gain can be calculated using the Air-Conditioning Contractors of

America (ACCA) Manual J or similar calculation procedures. To

conserve energy, many jurisdictions require that the building be

Residences

1.3

merged heat exchanger to transfer heat from the ground. Direct

expansion ground-source systems, with evaporators buried in the

ground, are occasionally used. The number of ground-source sys-

tems is growing rapidly, particularly of the ground-coupled type.

Water-source systems that extract heat from surface water (e.g.,

lakes or rivers) or city (tap) water are also used where local condi-

tions permit.

Water supply, quality, and disposal must be considered for

groundwater systems. Bose et al. (1985) provides detailed informa-

tion on these subjects. Secondary coolants for ground-coupled sys-

tems are discussed in this manual and in Chapter 20 of the 1997

ASHRAE Handbook—Fundamentals . Buried heat exchanger con-

figurations may be horizontal or vertical, with the vertical includ-

ing both multiple-shallow- and single-deep-well configurations.

Ground-coupled systems avoid water quality, quantity, and disposal

concerns but are sometimes more expensive than groundwater

systems. However, ground-coupled systems are usually more effi-

cient, especially when pumping power for the groundwater system

is considered.

Add-On Heat Pumps. In add-on systems, a heat pump is

added—often as a retrofit—to an existing furnace or boiler system.

The heat pump and combustion device are operated in one of two

ways: (1) alternately, depending on which is most cost-effective, or

(2) in parallel. In unitary bivalent heat pumps, the heat pump and

combustion device are grouped in a common chassis and cabinets to

provide similar benefits at lower installation costs.

Fuel-Fired Heat Pumps. Extensive research and development

has been conducted to develop fuel-fired heat pumps. They are

beginning to be marketed in North America.

Water-Heating Options. Heat pumps may be equipped with

desuperheaters (either integral or field-installed) to reclaim heat for

domestic water heating. Integrated space-conditioning and water-

heating heat pumps with an additional full-size condenser for water

heating are also available.

Hydronic Heating Systems—Boilers

With the growth of demand for central cooling systems, hydronic

systems have declined in popularity in new construction, but still

account for a significant portion of existing systems in northern cli-

mates. The fluid is heated in a central boiler and distributed by pip-

ing to terminal units (fan coils, radiators, radiant panels, or

baseboard convectors) in each room. Most recently installed resi-

dential systems use a forced circulation, multiple zone hot water

system with a series-loop piping arrangement. Chapters 12, 27, and

32 of the 2000 ASHRAE Handbook—Systems and Equipment have

more information on hydronics and hydronic.

Design water temperature is based on economic and comfort

considerations. Generally, higher temperatures result in lower first

costs because smaller terminal units are needed. However, losses

tend to be greater, resulting in higher operating costs and reduced

comfort due to the concentrated heat source. Typical design temper-

atures range from 80 to 95°C. For radiant panel systems, design

temperatures range from 45 to 75°C. The preferred control method

allows the water temperature to decrease as outdoor temperatures

rise. Provisions for the expansion and contraction of the piping and

heat distributing units and for the elimination of air from the

hydronic system are essential for quiet, leaktight operation.

Fossil fuel systems that condense water vapor from the flue gases

must be designed for return water temperatures in the range of 50 to

55°C for most of the heating season. Noncondensing systems must

maintain high enough water temperatures in the boiler to prevent

this condensation. If rapid heating is required, both terminal unit

and boiler size must be increased, although gross oversizing should

be avoided.

Zoned Heating Systems

Zoned systems offer the potential for lower operating costs,

because unoccupied areas can be kept at lower temperatures in the

winter and at higher temperatures in the summer. Common areas

can be maintained at lower temperatures at night and sleeping areas

at lower temperatures during the day.

One form of this system consists of individual heaters located in

each room. These heaters are usually electric or gas-fired. Electric

heaters are available in the following types: baseboard free-convec-

tion, wall insert (free-convection or forced-fan), radiant panels for

walls and ceilings, and radiant cables for walls, ceilings, and floors.

Matching equipment capacity to heating requirements is critical for

individual room systems. Heating delivery cannot be adjusted by

adjusting air or water flow, so greater precision in room-by-room

sizing is needed.

Individual heat pumps for each room or group of rooms (zone)

are another form of zoned electric heating. For example, two or

more small unitary heat pumps can be installed in two-story or large

one-story homes.

The multisplit heat pump consists of a central compressor and

an outdoor heat exchanger to service up to eight indoor zones.

Each zone uses one or more fan coils, with separate thermostatic

control for each zone. Such systems are used in both new and ret-

rofit construction.

A method for zoned heating in central ducted systems is the

zone-damper system. This consists of individual zone dampers

and thermostats combined with a zone control system. Both vari-

able-air-volume (damper position proportional to zone demand)

and on-off (damper fully open or fully closed in response to ther-

mostat) types are available. Such systems sometimes include a

provision to modulate to lower capacities when only a few zones

require heating.

Furnaces

Furnaces are fueled by gas (natural or propane), electricity, oil,

wood, or other combustibles. Gas, oil, and wood furnaces may draw

combustion air from the house or from outdoors. If the furnace

space is located such that combustion air is drawn from the out-

doors, the arrangement is called an isolated combustion system

(ICS). Furnaces are generally rated on an ICS basis. When outdoor

air is ducted to the combustion chamber, the arrangement is called

a direct vent system. This latter method is used for manufactured

home applications and some mid- and high-efficiency equipment

designs. Using outside air for combustion eliminates both the infil-

tration losses associated with the use of indoor air for combustion

and the stack losses associated with atmospherically induced draft

hood-equipped furnaces.

Two available types of high-efficiency gas furnaces are noncon-

densing and condensing. Both increase efficiency by adding or

improving heat exchanger surface area and reducing heat loss dur-

ing furnace off-times. The higher efficiency condensing type also

recovers more energy by condensing water vapor from the combus-

tion products. The condensate is developed in a high-grade stain-

less steel heat exchanger and is disposed of through a drain line.

Condensing furnaces generally use PVC for vent pipes and conden-

sate drains.

Wood-fueled furnaces are used in some areas. A recent advance

in wood furnaces is the addition of catalytic converters to enhance

the combustion process, increasing furnace efficiency and produc-

ing cleaner exhaust.

Chapters 28 and 29 of the 2000 ASHRAE Handbook—Systems

and Equipment include more detailed information on furnaces and

furnace efficiency.

Solar Heating

Both active and passive solar energy systems are sometimes used

to heat residences. In typical active systems, flat plate collectors

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