Chapter 7: Mechanical and Electrical Systems

Mechanical and Electrical Systems:

Two Methods of Heating or Cooling:
Air or Water

HVAC - Heating, Ventilation and Air-Conditioning.


Commercial Space:
Variable Air Volume (VAV)
High-velocity dual duct
Constant volume with reheat
and multi Zone systems.

Plenum- Space between Ceiling Grid and Slab. Duct work and electric work is generally run in this area.


KEY Components:
Flex Ducting
Supply
Return
Main duct

Heating Convector is used to circulate how water to heat the space.

Chase is used to vertically run ducts or pipes.

Mixing Box - (6"x 18", 24"x 60", 14" x 66" sizes)generally located in the plenum, controls the quantity and temperature of air going into a space. Thermostats are connected to the mixing box. Expensive and difficult to move.

Chase wall: two runs of studs with a few inches in between them.

Toilet carrier: Steel Frame work to carry the weight of a wall hung toilet.

Plenum can be used as a return air space.

Teflon-coated wire or conduits can be used in the plenum. exposed wire or combustible material is prohibited in the plenum space.

THERMOSTATS:

Normally located 48" AFF (44" for ADA). Away from exterior walls and heating sources.

WINDOWS:
2" min. from window covering (ex. blinds) to glass to avoid heat build up (cracking in glass).
1 1/2" min window covering to heating supply unit.

ACOUSTICAL SEPARATION:
All cracks to have acoustical sealant.
Also my cut the convector and re pipe (expensive)
or
Caulk or sealant in the convector.

Air-Supply Diffusers:
Lay-in Air Diffuser - used in ceiling grids (can also be used in gyp and plaster ceilings {trim flange}
residential diffuser - Residential application
Slot Air Diffuser - (long and narrow, used when square diffuser aren't feasible)

EX.) 18" x 12"
Width and height

USE CHAPTER 7 to Remember Symbols.


ELECTRICAL:
Designer is to show where to put outlets, data and switches.

Junction Boxes measure about 2" x4"
Larger boxes are about 4"x4"

Types of Cable:

under-Carpet Wiring - telephone wire, 120 V wire run under carpet. (can only be done with carpet tile)

RESIDENTIAL CONSTRUCTION - Outlets may not be more then 12' apart and there most be one on each wall surface where furn may be. (GOAL is to not run wire across door openings)

Ground Fault Interrupters - devices that detect leaks and disconnect power. Can be part of a circuit breaker or installed in an outlet.
(generally required in any area with the potential of water leakage)

In residential CD's Power and Data can be shown on construction plan, In commercial projects it is shown on a separate plan.

PLUMBING:
Commercial building plumbing is located at the core of the building.
Mechanical engineer drafts up plumbing plans.
4" pipe sloped at 1/4" per foot is used for drainage.
Soil Stack for human waste.
Vent Stack for waste that is not human waste.

FIRE PROTECTION AND LIFE SAFETY:
Contain the fire and limit the spread.
Places of Refuge (in high rise buildings)

4 Different Fire Detection:

Ionization Detector: considered early warning detectors. detects fires by particles not smoke.

Photoelectric Detector: aka smoke detector

Rise of Temperature Detector: heat generates the alarm

Flame Detector: ultraviolet radiation in flames sets these alarms off.

Detectors are required near fire doors, exits and corridors.

SPRINKLER SYSTEM:

IBC requires a sprinkler system in any building higher then 75'.

Side wall sprinklers are good for narrow spaces or corridors.
NFPA 13 is where most building codes refer to sprinkler codes.

FIRE HAZARD CLASSIFICATION OF BUILDINGS:
Light, Ordinary or Extra Hazard. Each classification in divided even further and these classification decide the distance between the sprinkler heads.

MAX spacings for sprinkler heads is 15' oc.
(max distance from the wall being 1/2 the required spacing)

STANDPIPES - Run vertically between floors and connect to fire hoses.

Check out Chapter 7 for Fire Extinguisher classifications A-D. A Class Fire Extinguisher being the Extinguisher for the least hazardous and D being the most.

Halogenated Agents can extinguish fire in a room where water would do damage. However, the chemical damages the ozone layer.