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another's responsibilities to avoid conflicts, such as the location of a light fixture and air diffuser in the same position. At the same time, both of these types of drawings are schematic in nature, allowing the contractor some latitude in the placement of the parts during field installations. Great care and forethought should go into the drawings, but existing conditions and the many variables present during the construction process may cause small deviations in the placement and installation of these systems.

Mechanical (HVAC) Plans

Engineers, architects, and mechanical contractors are the primary designers of HVAC plans (Figure 15-1). However, interior designers are often called on to coordinate the way the HVAC is installed and to monitor how it will affect the interiors of a building. A designer needs to be able to interpret the basic HVAC plans (particularly the reflected ceiling plan) for coordination of light fixtures, registers, grilles, thermostats, and other items that interface with the system (Figure 15-2). For example, an air diffuser in a wood-paneled ceiling needs to be carefully dimensioned to fall in the center of a panel, rather than at a joint or other haphazard position. The interior designer should understand the basic layout of the HVAC system and take care that furniture, furnishings, and miscellaneous equipment does not obstruct the operation of the system.

HVAC systems utilize a number of different mediums to regulate the environment in a building. The two most common are air and liquid. These carry energy produced by electricity, oil, or renewable sources such as solar and wind power. Liquid systems primarily use water as a transport medium; however, other fluids, such as refrigerants and oils, are also used. In the water system, a boiler is used to create steam. The steam is circulated through piping to radiators placed in the building spaces, creating a heating mode. In the cooling mode, water is chilled at the central plant and circulated to individual radiator units that cool the surrounding air and absorb heat, which is piped back to the central plant. In the air system, heated or cooled air is transported to the interior spaces with supply and return ducts. In residential projects, these ducts are generally run below floor joists, above the ceiling, or even in an attic space. In commercial work, the ducting is run in the space between a suspended ceiling and the structure above, such as the next floor, as shown in Figure 15-3. When this space is also used as a return air space or plenum, building codes limit the use of combustible and other hazardous materials in the plenum. In other cases, raised floor systems can be placed above the structural floor, and ducting runs in this accessible system. In both residential and commercial work, ducting is also sometimes run in wall cavities, although the space is generally limiting in large systems due to the larger sizes of ductwork required for moving large amounts of air.

Access is needed to HVAC components such as fire dampers, valves, and adjustable dampers. In suspended acoustical ceilings, a tile or two can be removed to gain access to the necessary parts. In gypsum board ceilings, special access doors are installed in strategically located areas. The interior designer should be able to read the plans and take note where these items might cause physical or aesthetic conflicts with the ceiling design.

The HVAC system also includes various controls such as thermostats and other monitoring equipment. The position of the thermostats is generally specified by the mechanical engineer. They are placed away from heat sources such as fireplaces, exterior walls, large expanses of exterior glass, and other features that may hinder their operation. Generally, they are located on the walls, and must be coordinated with other interior finishes and equipment

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Figure 15-4 The thermostat for the first floor of this apartment is located on an inside wall, next to the light switches.

note: light fixtures < ceil'g hvac shoujn as reflected ceil'g plan

Figure 15-4 The thermostat for the first floor of this apartment is located on an inside wall, next to the light switches.

note: light fixtures < ceil'g hvac shoujn as reflected ceil'g plan

ELECTRICAL PLAN

BAROMETRIC BYPASS DAMPER -ROOF-

BAROMETRIC BYPASS DAMPER -ROOF-

BYPASS DUCT TO DISCHARGE THRU SIDEWALL INTO TOP PORTION OF SKYLIGHT AREA TYP FURN #3 Sc #5

■ALL INSULATED DUCT SEE SPECIFICATIONS

METAL SUPPORT FRAME

Figure 15-5 Furnaces and ducting are drawn at a large scale in this sectional view of the attic for a small commercial building.

BYPASS DUCT TO DISCHARGE THRU SIDEWALL INTO TOP PORTION OF SKYLIGHT AREA TYP FURN #3 Sc #5

■ALL INSULATED DUCT SEE SPECIFICATIONS

METAL SUPPORT FRAME

:NLAR6EP SECTION « ATTIC HVAC

such as wall switches, wall sconces, etc., as illustrated in Figure 15-4. In large projects, there may be several thermostats to control heating and cooling in multiple zones of a building.

Scale of HVAC Plans

HVAC plans are generally drawn at the same scale as the floor plans. The most common scale is V4" = 1'-0" (1:50 metric) for residential and small commercial projects and 1/8" = 1'-0" (1:100 metric) for large commercial ones. The scale the HVAC plan is drawn at should be noted either adjacent to or directly below the drawing title. Other detailed and related equipment drawings might be enlarged with their respective scales shown on the drawing and referenced to the HVAC plan (Figure 15-5).

Drafting Standards for HVAC Plans

As HVAC systems carry water, air, electrical currents, or a combination of these, detailed drawings are made to show the layout of each system and its operation. The drawings for HVAC air supply equipment reflect the ductwork system and sizes needed to deliver and return the proper amount of air to each space, as shown in Figure 15-6. HVAC systems that carry water use drawings to indicate boiler equipment, piping sizes, and layouts.

In all of these systems, the equipment, piping, ducts, and other features are shown in a plan view. These floor plans should not be cluttered with notes, dimensions, room names, and other notations that might make the HVAC part of the plan difficult to read. Wall lines are often drawn lighter and thinner than the HVAC system lines in order to make the system particulars stand out clearly. In some instances, the ductwork might even be shaded for easier identification. The HVAC plans are schematic, using symbols to denote the various parts such as furnaces, ducts, control devices, and piping. Although professional firms might vary in the symbols they

12X8

12' WIDE BT 8' DEEP DUCT WITH DIRECTION OF AIR FLOW

DIAMETER ROUND DUCT WITH DIRECTION OF AIR FLOW

DUCT REDUCTION

10X8 12X8 p SIZE CHANGE

h AUTOMATIC OR MANUAL DAMPER <f ("CONTROLS VOLUME OF AIR FLOW;

AIR SUPPLY DUCT SEEN IN SECTION VIEW

RETURN AIR DUCT SEEN IN SECTION VIEW

FLOOR SUPPLY REGISTER

ROUND CEILNQ SUPPLY DIFFUSER OUTLET

arrows indicate direction of air flow

RECTANGULAR CEILNG SUPPLY DIFFUSER OUTLET

□ LINEAR AIR DIFFUSER

THERMOSTAT

HEATING AND AIR CONDITIONING SYMBOLS

FURNACE COMBUSTION AIR AND FLUE PIPES SIZED PER MANUFACTURERS RECOMMENDATIONS

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use, some are fairly standard, as seen in Figure 15-7. The symbols are cross-referenced to a schedule that fully describes the piece of equipment or assembly. In some cases, a single line is used to represent the ductwork or piping (Figure 15-8). A note is then added next to the run indicating the size of the duct or pipe. In ducting, the first number generally refers to the width and the second number to the height of the assembly. In air systems, arrows are used to indicate the direction of flow through the ducting and at the dif-fusers. Isometric drawings are also used to explain HVAC assemblies or particulars of the system, as illustrated in Figure 15-9. These are prepared by the mechanical engineer to more clearly show the components of system.

Figure 15-6 This reflected ceiling plan shows the HVAC duct sizes and location of the supply and return registers where they penetrate the ceiling.

Figure 15-7 (left) HVAC drawings employ basic symbols to illustrate components.

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