ARE | MEP
If the street main provides 100 psi and there is a 10 psi loss due to friction, a faucet can be placed ______ feet high if the required pressure at fixture is 10psi
184 feet
Psychrometric chart - what is wet bulb temp if dry is 60F and relative humidity is 70 per cent? 50F 60F 96F 104F
50F
If a lamp of 2400 cp intensity results in an illumination of 24 fc at 10 feet, the illumination at 20 feet is _____?
6 fc
Which of the following uses the latent heat of evaporation to transfer heat? A. evaporative chiller B. multizone system C. unitary system D. variable air volume system
A. evaporative chiller
Forced Air Equation
A=144 Q cfm/v Qcfm=the flow rate in cubic feet per minute v=the velocity measured in feet per minute A=the cross sectional area of the duct in square inches
Three-Phase AC current
AC current three separate circuits 120 degrees out of phase + one neutral circuit HIGHER VOLTAGE allows for larger number of fixtures to be on a single circuit w/o current increase 208 / 480 V 120 / 208 V 277 / 480 V
Single-Phase electric power
AC power used when loads are mostly heating and lighting
Hydronic Four Pipe
HEAT / COOL simultaneously high first cost can combine with forced air
Specific Heat (Cp)
Heat of a specific material - two objects at the same temperature may store different amounts of heat BTU / lb
Ohm's Law
I = V / R P = V x I P = power (watts) I = current (amps) --> water > flow V = voltage (volts) --> water > potential /height /pressure R = resistance (ohms) --> water > resistance to flow
Lighting (q1)
This heat must be removed by the cooling equipment like any other load. q1=3.4W W= the wattage of the equipment.
specific heat
Two objects at the same temperature may store different amounts of heat. This storage capacity is called the specific heat
Which of the following hydronic systems are parallel? (three) One pipe Two pipe Three pipe Four pipe Five pipe
Two, Three, and Four pipe One pipe is run in a series. Five pipe is not used.
Variable Air Volume (VAV)
VARIABLE flow rate ducting by ZONE can HEAT / COOL simultaneously most common and efficient system maintenance nightmare
Which of the following plumbing fixture types is NOT permitted to connect to a waste stack vent? Bidets Utility Sinks Lavatories Water Closets
Water Closets
Design Day
used to design and size a heating system that determines the day cooler than 98% of all days in the year experience in a climate
Gate Valve
used when control is either fully on or off little friction loss
Globe Valve
used when flow is controlled variably friction loss is high ex. faucets, hose bib
Heat Pump
water circulated each ZONE has heat pump and fan efficient high initial cost (duct + pipes) may require boiler / chiller
Sensible Heat
when transferred heat causes a change in temperature
Qcltd = U (A) CLTD Qetd = U (A) ETD
where CLRD is Cooling Load Temperature Differential where ETD is Equivalent Temperature Differential
Air Changes per Hour (ACH)
a rough estimate of how much whole room / building air is replaced by outdoor air per hour
Unitary System
air DIRECTLY from exterior one unit / ZONE when ducts are impracticable good for RENTERS
Induction
air supplied UNDER PRESSURE return air + ext. air small ducts good for perimeter rooms
Ball Valve
allows one way flow is opened / closed by pressure on a ball used for regulating flow
Time of day affects...? (three) declination angle altitude angle azimuth angle intensity of the sun speed of transit
altitude angle azimuth angle intensity of the sun
Which has more embodied energy - wood or aluminum?
aluminum requires about 100 TIMES as much as wood
Check Valve
automatically allows water to flow in one direction backflow causes the valve to close typically used to prevent sanitary waste from flowing back
Doubling the mass of a theoretical wall causes its sound transmission to drop 6 dB gain 6 dB drop 3 dB gain 3 dB
drop 6 dB
Doubling the distance from the source to the receiver would result in a drop of 6 dB gain of 6 dB drop of 3 dB gain of 3 dB
drop of 3 dB
Fan Coil System
efficient HEAT / COOL simultaneously ZONE HYDRONIC FOUR + FORCED AIR highest initial cost
Doubling the number of sources at a given intensity would result in a drop of 6 dB gain of 6 dB drop of 3 dB gain of 3 dB
gain of 3 dB
Latent Heat (BTU)
heat that causes a change of state
Hydronic Three Pipe
hot / cold mixed at return HEAT / COOL simultaneously less efficient than two / four can combine with forced air
LEDs
low in power consumption diodes emit light when circuit is connected runs on DC power
Hydronic Single Pipe
low initial cost (v piping) cannot be long (temp drops) CANNOT heat / cool simultaneously can combine with forced air
High Pressure Sodium
made of ceramic > resist hot sodium high efficacy (80 - 140 lumens / watt) life of 24,000 hours wide variety of colors
Along a means of egress, what should the minimum illumination level be?
not less than 1 fc at floor UNLESS theaters, etc. - can be reduced during performances to no less than 0.2 fc
Double Duct System
one for heat, one for cool two ducts join at MIXING BOX in ZONE constant volume expensive (2x ductwork) greatest energy suck with this common in hospitals
Switching
one switch location: (1) two-way switches used two switch locations: (2) three-way switches used three or more switch locations: (2) three-way switches and (1+) four-way switches
Interlocked Armored Cable
pre-wrapped set of wires in interlocking metal spiral armor factory-assembled NOT underground NOT in concrete "BX"
Insolation is an example of: radiation conduction convection latent heat transfer
radiation
CLTD approximates the effects of which of the following? radiation conduction convection latent heat
radiation conduction
Which of the following fixtures or types of equipment must have their waste outlets equipped with air gaps adequate to prevent contamination due to any possible backup of sewage through the waste piping? (two) refrigerators heat recovery units water closets bathtubs sterilizers waste interceptors
refrigerators sterilizers
The psychrometric chart plots which of the following factors? (two) relative humidity air motion mean radiant temperature air temperature convection current surface temperature
relative humidity air temperature
Low Pressure Sodium
requires a ballast highest efficacy (150 lumens / watt) monochromatic YELLOW light used for safety (parking garages, etc.)
Sheathed Wire / "Romex"
residential construction wires encased in plastic sheath NOT in commercial garages NOT in concrete "NM" or "NMC"
Flexible Metal Conduit
residential or remodel available w/ and w/o flexible waterproof NOT underground "Greenfield" or "flex"
What is the name of the sensing surface of the eye? Lens Iris Cilia Retina
retina
Reheat (constant volume)
return air + fresh air combined + conditioned CONSTANT volume, low temp small ducts ^ energy (cooling most of time) coils / ZONE economizer cycle
Rigid Conduit
safest THREADED connection in exterior, must be galvanized in interior, may be enamel-coated
Angle Valve
screw a washer down to shut the flow off OR opened and regulated flow used mostly for plumbing fixtures
Hydronic Two Pipe
separate supply / return CANNOT heat / cool simultaneously can combine with forced air
Intermediate Metallic Conduit (IMC)
steel thinner walls than plumbing pipe slightly less expensive than rigid conduit
The Mean Radiant Temp (MRT) relates to: air temp surrounding surface temps body temp all
surrounding surface temp
Degree Day (DD)
the average yearly difference between the indoor temperature and outdoor temperature. Typically, a ref of 65 deg.
Reverberation time is (two): the time required for a sound to decay 60 dB in a space the time it takes for an echo to return longer in a dead space, shorter in a live space
the time required for a sound to decay 60 dB in a space longer in a dead space, shorter in a live space
A three-wire transformer means: the primary winding is one of three input options the transformer generates three-phase current the secondary winding allows two different voltage takeoffs there is a tertiary winding
the transformer generates three-phase current
A degree day is directly related to (two)? the weather in an area over a period of time a reference temp a design day
the weather in an area over a period of time a reference temp
Electrical Metallic Tubing (EMT)
thinnest of metal conduit galvanized connections via CLAMPING "thin wall"
Enthalpy (H)
total heat loss in a substance (latent + sensible) (in BTU)
If the MRT is low, which way does the comfort zone shift? toward higher ambient temps toward lower ambient temps toward lower relative humidities
toward higher ambient temps
If the unit price of a central air-conditioning system is $1000 per ton, what would be the total cost of a system able to provide cooling (refrigeration) for 90,000 BTW / hr?
$8,000
1 kW = mW?
1 kW = 1000 mW
Three steps to determining CLTD
1. Determine the wall classification or group of the wall or roof section. 2. Determine the base CLTD from the time of day, wall type, wall orientation, and wall or roof color. 3. Adjust the CLTD based on the temperature history of the last 24 hours.
If the voltage between the neutral and the peak of a three-phase current is 120 volts, what is the voltage between two phases? 120 volts 208 volts 240 volts 277 volts
208 volts
The maximum acceptable IL for a hospital is: 100 dB 70 dB 40 dB 10 dB
40 dB
The flush control for a handicapped accessible urinal is a maximum of how many inches above the floor?
44 inches
Emergency power systems shall provide back-up power for a minimum of how long?
90 minutes
Duct sizing
A = 144Q/v A = cross sectional area of duct (square inches) Q = flow rate (feet^3 / min) v = velocity (feet / min)
Sustainable design is primarily concerned with? Economics Aesthetics Environment Mechanical Systems
All
All of the following are capable of reversing the otherwise invariant flow of heat from hotter to cooler objects, EXCEPT A. the heat pump system B. the variable air volume system C. the refrigeration cycle D. the evaporative chiller
B. the variable air volume system
Which color represents the highest Kelvin temperature and the shortest wavelength? Red Yellow Green Blue
BLUE
Which part of the refrigeration cycle is the hottest? A. evaporator B. Compressor C. Condenser D. Valve
C. Condenser
The Natural Step is an environmental approach with which principles? Biosphere affecting humans is relatively stable and resilient, including 5 miles into earth's crust and 5 miles up to troposphere Improved technology has increased the number and quantity of available natural resources Toxic substances released into either the sea or atmosphere will only influence areas adjacent to the toxic source. Using building materials that are recycled is an adequate sustainable design approach
NONE!
What is the minimum illumination at an exit sign?
Not less than 5 fc
Single Phase Circuit calculation
P = V x I x PF P = power (watts) I = current (amps) --> water > flow V = voltage (volts) --> water > potential /height /pressure PF = power factor (decimal)
Three-Phase Circuit calculation
P = V x I x PF x (sq root of 3) P = power (watts) I = current (amps) --> water > flow V = voltage (volts) --> water > potential /height /pressure PF = power factor (decimal)
Heat loss includes: Qc Qr Qs Qi Qcltd Qm
Qc Qs Qi
R-value calc
R = x/k r = resistivity x = thickness k = conductivity
single duct system
Simplest - often found in residential constant air volume CANNOT heat and cool simultaneously rate of flow by damper / diffuser lower initial cost (less ductwork)
Which is best for short reverberation times? Speech Pipe Organ
Speech
Why is storm drainage separate from sanitary? Storm drainage is more polluted Storm tends to flow at high volumes - too high to be treatable by sewage plant Storm is not pressurized
Storm tends to flow at high volumes - too high to be treatable by sewage plant
Radiation
The method by which heat is transferred between two objects not in contact and not shielded from each other.
Which of the following hydronic systems can provide both heating and cooling simultaneously? (two) One pipe Two pipe Three pipe Four pipe
Three and Four pipe
Ahwahnee principles (two): Communities with only residential use should be relegated to areas outside the central biz district Preserved open spaces should be either wildlife habitats or recreational areas Transportation planning should include roads, pedestrian paths, bike paths, and mass transit systems Job creation and econ. diversity is a desired goal
Transportation planning should include roads, pedestrian paths, bike paths, and mass transit systems Job creation and econ. diversity is a desired goal
Greenhouse Effect
We normally consider glass to be transparent, since it has a very high transmissivity, which is what causes the "greenhouse effect."
Sensible heat
When transferred heat causes a change in temperature it is called sensible heat.
latent heat
When transferred heat causes a change of state (ice to water or water to vapor) it is called latent heat.
Mercury Vapor
blue-green color high efficacy (30-50 lumens / watt) life of 24000 hours for large overhead lighting (sports complexes, etc.)
Transmission Loss (TL) is dependent on:
construction, mass, stiffness
Which of the following piping materials is heated when two pieces are joined? steel copper iron plastic
copper
Doubling the mass of a wall will increase / decrease the transmission level by how much?
increase, between 5-6 dB
A downfeed system differs from a pneumatic system in that a downfeed: is necessary only when the street main pressure would not supply the upper floors is not pressurized has no storage tank
is not pressurized
Rain water... (three)? is slightly acidic is slightly alkaline tends to corrode metal pipes is less healthful than ground water
is slightly acidic tends to corrode metal pipes is less healthful than ground water
x/k = R
k Conductivity r. Resistivity X thickness
Hot arid climate (three): large roof overhangs to screen the sun thermal mass to damp out temp swings large openings to the outside to improve ventilation evaporation to increase humidity dark-colored roofs lush landscaping to create cooling effect
large roof overhangs to screen the sun thermal mass to damp out temp swings evaporation to increase humidity
Multizone System
like double duct, but MIXING BOX inside mech good for rectangle with a few zones easy to sub monitor (office RENTAL $$$ first cost (^ ductwork)
Metal Halide
like mercury vapor but metal halides are added high efficacy (50 - 100 lumens / watt) whiter, more natural light shorter life
