Ch 18 Elec Mech Flashcards
Mechanical systems include . . .
Heating and cooling, plumbing, and fire protection.
Electrical systems include . . .
Power, lighting, telephone, and other communication systems.
The NCIDQ exam oftn refers to stairways as . . .
Vertical Transportation
Although the interior designer is NOT responsible for designing or producing construction drawings for structural, mechanical, and electrical systems, he or she must know . . .
when and how to coordinate with consulting engineers, how to read consultants’ drawings, and how to make design decisions based on these systems.
What are the two primary methods of heating and cooling use ___ or _____.
Air or Water
What HVAC systems cool or heat spaces by conditioned air alone.
All-Air Systems
How does an all-air HVAC system work?
Heat is transported to the space with supply and return air ducts.
What is a common example of an all-air heating system and how does it work?
A residential forced hot air furnace - A boiler powered by oil or gas heats air that is distributed throughout the house in ductwork. Return air ducts in each room collect the cooled air and return it to the furnace for reheating. If necessary an A/C unit is connected to the same ductwork to provide cooled and dehumidified air.
What types of HVAC units are used in commercial buildings?
Variable Air Volume (VAV), High-Velocity Dual Duct, Constant Volume w/ Reheat, and Multizone Systems. (All types require supply air ductwork, registers, and return air grilles in all spaces. Registers are connected to the supply air ductwork and can be adjusted control the direction of air flow and the volume of air coming through them).
What is done when separate ductwork is not used for return air?
Grilles are placed in the suspended ceiling to collect return air. The mechanical system draws the return air back to a central collecting point where it is then returned through ducts to the building’s heating plant.
Plenum
The space between the suspended ceiling and the structural floor above.
What is required at fire-rated partitions that extend above the suspended ceiling?
Supply air ducts and openings for the return air must be provided. At the locations where the fire wall is penetrated, fire dampers are required that automatically close in the event of a fire.
What is the benefit of supply air registers that are connected to flexible ducting?
This allows adjustability in the exact location of an air register if its location is in conflict with some other ceiling-mounted item.
Return air grilles are generally NOT . . .
connected to ducts in commercial construction. This allows them to be relocated if overall circulation is maintained. THE MECHANICAL ENGINEER SHOULD BE CONSULTED TO DETERMINE HOW MUCH THE REGISTERS CAN BE MOVED.
How do all-water heating systems work?
All-water heating systems use some type convector (coil unit in each space through which hot water is circulated). The hot water heats the fins of the coil units, and air is heated as it is drawn over the fins. The air may be circulated by CONVECTION, as with most baseboard residential fin-tube radiators, or by forced circulation created with a fan.
Combination systems that used ductwork for supplying fresh air but used water to heat or cool the air before it is introduced into the conditioned space is a ___________ ___________ system
Terminal Reheat Systems
Where are small ducts and plumbing pipes run in residential construction?
Within the walls and floor joists.
How are horizontal ducts run in a house?
Below floor joists or in a dropped ceiling, or a furred down space may be built to conceal them.
Where are horizontal ducts run in commercial construction?
In the plenum. Large ducts may occupy most of the vertical distance between the structure and the suspended ceiling. This may make it difficult/impossible to installed recessed light fixtures.
Where are vertical ducts run in commercial construction?
Run within their own chases.
What alternate fixtures to a standard line-voltage recessed downlight can be used when ducts take up all/most of the space in the plenum?
Low-voltage or low-clearance lights fixtures.
Adjusts the quantity or temperature of air going into a space from the main air supply line(s), reduces the velocity of air, and attenuates noise.
Mixing Box
A designer needs to consider the location of ____ ______ when planning the ceiling layout.
Mixing Boxes
Lines from the _______ are connected to the mixing boxes.
Thermostats
With variable air volume systems, the VAV box . . .
varies the quantity of air. One duct leads in and one or several lead out and are attached to registers mounted in the ceiling.
Where is a VAV box typically placed?
Aboved the ceiling, within or near the space it serves.
How does the mixing box work with dual-duct systems?
The mixing box mixes cool and hot air, coming into it from two separate ducts, and distributes the mixed air to ducts serving individual rooms or spaces.
How does a terminal reheat system work?
The box contains a hot-water coil that provides additional heat to the air stream.
How can a terminal reheat system be identified?
These are easily identified by air ducts and copper pipes leading into them.
What must be done before locating light fixtures and other recessed items?
Verify the sizes and locations of ductwork, mixing boxed, and piping.
What is the BEST way to confirm the location of existing HVAC, plumbing, electrical, and fire protection, and why?
Onsite viewing of the space above the ceiling is the best way to confirm the locations. This is because actual construction seldom exactly follows the drawings.
WHAT must be discussed with WHO if the relocation of HVAC equipment or piping is contemplated?
The cost, time, and heating and cooling implications should be discussed with the mechanical engineer, contractor, and client.
What is an access floor?
A false floor of individual panels raised above the structural floor with pedestals. It is most commonly used to run electrical, communication, and computer wiring, It can also be used for some types of HVAC ductwork that serves individual workstations.
A steel framework that is bolted to the floor inside a pipe chase and carried the weight of wall-hung toilets.
Toilet Carrier
Chase Wall
A deeper wall in which larger pipes are run. The wall consists of two runs of studs separated by several inches, the exact dimension being determined by the largest pipe or duct that has to be concealed. Only the finish side of each run of studs is covered with GWB. Chase walls are commonly used between back-to-back commercial toilet rooms where extensive plumbing work and toilet carriers are required.
What does the code prohibit when the plenum is used as a return air space?
The use of combustible materials (e.g. wood or exposed wire) within the space. If required by the AHJ, fire-rated DIVIDERS must be installed to limit the spread of fire and smoke horizontally. Normally, such dividers are simply an extension of a fire-rated partition.
How is wiring run in a return air space plenum?
Either use plenum-rated (e.g. Teflon coated) telephone and communication wiring or run the wires in steel conduits.
Code requires access to these items . . .
Valves, fire dampers, heating coils, mechanical equipment, electrical junction boxes, communication junction boxes, and similar devices. If these components are located above a suspended ceiling, access is provided by removing a ceiling tile. In locations such as a GWB ceiling, access doors are required for anything that might need to be inspected, adjusted, or repaired.
Access Doors
Small steel doors with frames that are opened by using a thumb turn or a key. They are available as a fire-rated assembly.
What determines the location of thermostats?
By the mechanical engineer so they are away from exterior walls, heat sources, or other areas that may adversely affect their operation.
At what height are thermostats usually mounted?
48” above the floor, but this must be coordinated with light switches and other nearby wall-mounted control devices. It also must be coordinated with the max. allowable reach distances for ADA, which may lower the heights to 44” for an obstructed forward reach.
Who should coordinate the locations of supply air diffusers and return air grilles with other ceiling items such as lights, sprinkler heads, smoke detectors, speakers, etc.?
Interior Designer (however the mechanical engineer must be consulted to verify that the desired types and locations of supply air and return air devices to not adversely affect the operation of the HVAC system).
In commercial construction, there should be at least ___ inches between the glass and any window covering to avoid excessive heat buildup, which might cause the glass to crack or break.
2”
What is the minimum clearance between the sill with an HVAC supply and the bottom of a window covering?
1-1/2”
What is the minimum clearance from the edge of the mullion to the window covering?
1-1/2”
What is the minimum clearance from the header to the top of the window covering?
1-1/2”
What affect do window coverings have the HVAC of a space?
They can affect the heating and cooling load in a space and may interfere with supply air diffusers or other heating units near the window.
What must the designer do to verify the window coverings do not affect the HVAC?
The designer should have the mechanical engineer or architect check the designer’s proposed type, size, and mounting to verify that they will not create a problem with the HVAC system.
What must be done with HVAC when remodeling or adding on to a residence?
The existing locations of ductwork and registers may not work if remodeling is extensive, and a mechanical contractor or engineer should be consulted to determine if the existing furnace has adequate capacity to change or add onto a residence, and also to determine how ducts and registers may need to be relocated, if necessary.
In commercial construction, most HVAC systems are designed to work independently of . . .
partition relocation and furniture placement. However, in some cases HVAC zones are designed for one layout and may not work with the desired zoning of a new plan.
What must the interior designer consider in regards to furniture placement?
The designer may want to consider the locations of floor registers, fin-tube baseboard radiators, and other equipment as they affect the placement of furniture and built-in woodwork.
Mechanical and electrical services often pose problems with maintaining ______ ________, especially in offices spaces where ducts, convectors, and piping run continuously along an exterior wall while partitions intersect the exterior wall at regular intervals.
Acoustic Separation
Where may special detailing or construction be required to maintain acoustical separation?
Special detailing or construction may be required to create a continuous sound seal around the floor, around the ceiling, above the ceiling, and along the perimeter walls. For example, the cracks between the wallboard and all pipe and duct penetrations must be sealed with acoustic sealant.
What acoustical problem can occur at walls that intersect exterior walls with convectors running near the floor and how can the problem be corrected?
The openings in the convector allow warm air to circulate and allows sound to penetrate and travel inside the convector, past the partition, and out the openings on the other side. The convector must be modified in some way to prevent this, either by cutting the convector and piping (DIFFICULT, EXPENSIVE OPTION) or be sealing inside the convector while still allowing the hot water pipe to run continuously.
Diffusers that can be used when appearance of the air distribution device needs to be minimized or when the available space does not allow a square diffuser.
.Slot Air Diffusers
They are long and narrow and contain from two to eight slots, resulting in a finished opening of about 3 in. to 8 in. in width. They can be used for either supply or return air. There is a box above the slots that is as long as the slots. Air is supplied by a flexible round duct attached to the side of the box. Slot air diffusers are available for either suspended or GWB/plaster ceilings. They are usually used with GWB ceilings to provide a trim, unobtrusive method of distributing air
Where are 1 ft or 2 ft square diffusers commonly used, and why?
They use used in suspended acoustical ceilings because they fit within standard ceiling grids, and are easy to install and inexpensive.
What steps can the interior designer take to minimize the energy use and improv IAQ?
The designer may plan a space to utilize daylighting as much as possible or may propose to use a displacement ventilation system.
Why must interior designers be able to read the basics of HVAC plans?
So they can review drawings to verify existing conditions and coordinate the interior design work with the mechanical engineer’s work.
HVAC drawings normally are drawing with a ____ _______ representing piping and ductwork.
Single Line
Ducts are indicated with a line and a number such as 18 x 12. The first number indicates the ____ of the duct in inches, and the second number indicates its ______ in inches.
Width; Height
What do electrical systems include?
Power for lighting, convenience outlets, and fixed equipment.
What does the electrical contractor or engineer design and specify?
Exact types of circuiting, wire sizes, and other technical aspects of the electrical systems.
What is the interior designer responsible for schematically showing in regards to electric?
The desired locations of outlets and switches, where power is required for special built-in equipment, and the appearance of cover plates and other visible electrical devices.
The interior designer should be familiar with the rudiments of . . .
power supply.
___________ supply power throughout a building and extend from circuits breaker boxes to the individual switches, lights, and outlets.
Conductors
Nonmetallic (NM) Sheathed Cable (trade name Romex)
A type of conductor that consists of two or more plastic-insulated conductors and ground wire surrounded by a moisture-resistant plastic jacket. This type of cable can be used in WOOD STUD RESIDENTIAL buildings and buildings not exceeding three floors, as long as it is used with wood studs and protected from damage by being concealed behind walls and ceilings.
Flexible Metal-Clad Cable, or Armour Cable (AC) (Trade name BX, sometimes called “flex”)
Type of conductor that consists of two or more plastic-insulated conductors encased in a continuous spiral-wound strip of steel tape. It is used in remodeling work because it can be PULLED THROUGH EXISTING SPACES WITHIN A BUILDING. It is also used to connect commercial light fixtures so they can be relocated in a suspended ceiling.
A thin, flat, protected wire that can be laid under carpet without protruding. Cable for both 120 V circuits and telephone lines is available, but it must be used with carpet tiles so that it is readily accessible.
Under-Carpet Wiring
Steel or approved plastic boxes to which the conduit or other cable system is attached. For single switches and duplex outlets, they measure about 2” x 4”. Larger boxes are 4” square, and several can be connected if there are more than two switches or two duplex outlets.
Junction Boxes
When are conductors required to run through metal conduit (or other approved carriers) and why?
For commercial construction and large multifamily residential constructio, individual plastic-insulated conductors must be placed in metal conduit (or other approved carriers). Conduit supports and protects the wiring, serves as a system ground, and protects the surrounding construction from fire if the wire overheats or shorts.
Where are junction boxes required?
Outlets and other types of connections to the power supply must be made in junction boxes. They are also required where light fixtures are connected to the electrical system.
Special power outlets that must be placed on their own circuit. They prevent various types of electrical interference from disturbing sensitive electrical equipment (computers) connected to them. There circuits should be clearly differentiated on the plan, and the exact electrical requirements of the equipment should be given to the electrical engineer. Circuits that require voltages greater than 120 V must also be identified. These include outlets for ELECTRIC RANGES, DRYERS, COPIERS, and other special equipment.
Dedicated Circuits
What is the maximum spacing for residential outlets by code?
Outlets must be spaced no more than 12 ft apart, and there must be a duplex outlet on each wall surface where furniture might be placed so lamp cords and the like do not have to be stretched across door openings.
What are three types of protection provided in electrical wiring?
Circuit breakers, grounding, and ground fault circuit interrupters.
A separate wire in addition to the two that provide power.
Grounding
The grounding of an electrical system prevents a dangerous shock if someone touches an appliance with a short circuit and simultaneously touches a ground path such as a water pipe. The ground provides a path for the fault.
If the circuit is overloaded, the ____ _______ trip off in the panel box.
Circuit Breakers
Devices that detect small current leaks and disconnect the power to the circuit or appliance. GFIs can be part of a circuit breaker or installed as an outlet.
Ground Fault Interrupters (GFIs)
What problems can a ground fault create?
The current required to trip a circuit breaker is high and small leaks of current can continue unnoticed until someone received a dangerous shock or a fire develops.
Where are GFIs required?
For outdoor outlets and in bathrooms, kitchens, and basements, as well as other locations specified in the National Electrical Code.
What plan are telephone and communication systems usually shown?
Same plan as the power outlets.
What is the interior designer responsible for showing in regard to the telephone and communication systems plan?
The designer is responsible for showing the locations of items like telephones, intercommunication systems, P.A. speakers, buzzers, and computer terminals. *As with power outlets, the actual circuiting, wire sizes, and connections to central equipment are usually determined by the electrical engineer or the contractor responsible for installing the equipment.
Telephone and communication systems are __-______ systems.
Low-Voltage
How are telephone and communication systems typically installed?
An outlet box is provided at the connection in the wall, and the wire is run within the walls and ceiling spaces without conduit.
Because telephone and communication systems are low-voltage . . .
the requirements for conduit and other protection are not quite as stringent as for high-voltage power. Although, some commercial construction requires that all cable be protected in conduit to avoid having it catch fire or release toxic fumes in case of a fire. Special plenum-rated cable is available that does not require conduit, but it is more expensive than standard cable.
What plan would the interior designer locate electrical, telephone and communication outlets on for residential construction?
Construction Floor Plan
What plan would the interior designer locate electrical, telephone and communication outlets on for commercial construction?
Power Plan
What does the designer show on the power plan besides the outlets?
Exact dimensions if outlet locations are critical.
What plan can outlets be shown on besides the construction (residential) and power (commercial) plans?
Furniture plan, because they most often directly relate to the placement of desks, seating groups, and other furniture. The power plans developed by the interior designer are used by the electrical engineer to draw the electrical plan.
What does the electrical plan include? Who is responsible for this drawing?
The electrical engineer creates the electrical plan, which includes all the detailed information such as circuiting, wire size, conduit size, panel boxes, and other data required by the electrical contractor.
What are interior designers often required to do with plumbing fixtures?
Locate plumbing fixtures in new construction and remodeling work.
What is something the interior designer must know regarding plumbing? Why?
Because plumbing is such a significant cost and can impose limitations on space planning, the designer should have a good understanding of plumbing basics and how to coordinate the design with existing building services.
What are the two major components of plumbing?
Water Supply (cold & hot) & Drainage
In all plumbing installations, water is supplied under . . .
pressure to individual plumbing fixtures.
What are plumbing SUPPLY lines easy to locate in walls and ceilings?
Because supply water is supplied under pressure, and because the pipes are generally small, it is easy to locate pipes in wall and ceiling cavities, even if it is some distance from the main source of water.
Drainage systems work by _______.
Gravity
Located at every fixture and are designed to catch and hold a quantity of water to provide a seal that prevents gases from the sewage system from entering the building.
Trap
Traps are connected to the actual drainage piping, but they must also be connected to vents. From the trap, sewage travels in fixture branch lines to a vertical stack
What is required of drainage piping?
The drainage piping must be sloped down to carry waste water away. Also, vent pipes are required.
