PPD Flashcards
What configurations does a heat pump come in?
Air-air
Air-water
Water-water
What configuration of heat pump is most common in small buildings?
Air-air
What is a split-system?
A HVAC system with interior and exterior components
In a split system, where is the condenser located?
Outside
What is a primary attraction of heat pumps in heating mode?
Heat mode can deliver more energy than it consumes (as electricity)
What does the rating SEER express?
Btu/h removed for each watt of energy unit input, over the cooling season
What does a higher SEER number mean?
A more efficient heat pump
Where should air-air heat pump not be used and why?
Cold climates
If there is less heat in the air, the heat pump needs to use a back-up electric resistance heating unit. This ends the efficiency advantage.
What type of heat pump should be used in cold climates?
Water-air
Wells, solar-heated stoarge or water from the ground
What is a single automatic pushbutton control?
1 call at a time
Uninterrupted trip per each call
When is a single automatic pushbutton control used?
Single-family residence and light-use freight
What is collective control?
Cars stop at each floor registering a call irrespective of direction.
Why is collective control not used anymore?
Slow and annoying service as calls aren’t registered in response to direction.
What is selective collective operation?
Collects all waiting up calls and collects all waiting down calls.
Where do you see selective collective operation?
Moderate service requirements
Multi-famiy, small offices and professional buildings
What can be added to selective collective operation?
Group control scheme
Assigns each hall call to the car best suited to answer
What is the downside to selective collective operation?
Bunching of cars can create longer wait times
What are the limits of selective collective operation?
Best when 2 cars. 3 cars can work, but you end up with bunching. More than 3 is not feasible.
What is destination dispatch?
A type of computerized system control
What are the 2 main categories of elevator?
Traction and hydraulic
What are the limitations of a hydraulic elevator?
Slow
Limited in distance
Not efficient
Chance of failure
What are the benefits of traction elevators?
More efficient
Last longer
Require less maintenance
Faster
Smoother ride
What are the design RoTs for hydraulic elevators?
2-5 floors
45’ max
What are the 4 types of hydraulic elevators?
- Direct Plunger
- Holeless
- Roped Hydro
- Telescoping Holeless
What is the max lift of a holeless elevator?
15’
What are the 2 types of traction elevator?
Geared and gearless
What are the design RoTs for geared traction elevators?
150’ max
5-15 stops
500 fpm
What are design RoTs for gearless traction elevators?
2000’ max
15-60+ stops
2400 fpm
Where are geared traction elevators used?
Where torque and bigger lifting requirements are needed
Freight elevators
In a traditional gearless traction elevator, where is the motor and controls?
On top of the elevator
What is the required area for hoistway venting?
3.5% of hoistway or 3 SF, whichever is bigger
What is voltage?
Pressure
What is current?
Flow of electricity
What do batteries run on?
DC - direct current
What is Ohm’s Law?
W = IV
Watts = Current x Voltage
Power = Current x Pressure
What are the units for Ohm’s Law?
Power = Watts
Current = Amps
Voltage = Volts
When is a thicker electrical wire needed?
To handle higher pressure - therefore higher wattage
How do transformers work?
Ratio of windings
Do you meter on the high voltage or low voltage side of a transformer?
Low voltage as it’s cheaper and not as risky
What is the typical electrical supply for a small building?
120 V, Single Phase, 2 Wire
What is the typical electrical supply for a single family residence?
120 V / 240 V, Single Phase, 3 Wire
What is 3 phase?
Singing in the round
Voltage is staggered, so having 3 phase means that there is always a consistent voltage supply
What should be used for a building larger than a single family residence, but less than 40,000 SF?
120 V / 208 V, 3 Phase, 4 Wire
What should be used for a larger building over 40,000 SF?
277 V / 408 V, 3 Phase, 4 Wire
In a 277 V / 408 V, 3 Phase, 4 Wire building, what needs to be added in the building?
A 408 V to 120 V transformer to supply outlets
What is a rectifier?
Changes AC to DC
What is a inverter?
Changes DC to AC
What does GFI stand for?
Ground Fault Interupter
What is a high albedo roof?
A light colored roof that absorbs less heat
What is a high emissivity roof?
Roof that releases the heat that was absorbed back to the night sky
What is EPDM?
Roofing membrane
Rubber membrane for large low-sloped roofs and roofs with few penetrations
For a seismic zone, does the entire building need to be fully braced?
Not necessarily
Just a portion of the building frame can be braced for seismic activity
What does temperate climate mean?
Cold winters, warm summers
Why are large mechanical items placed on an elevated pad?
Housekeeping pad - stops things from rolling underneath
Why is there a drain underneath AHUs?
To capture condensation from the cooling coil
What is displacement ventilation?
Air drawn from a plenum underneath the room, into a space and then exhausted up the top
What is a great typology to use displacement ventilation?
Theatres / Auditorium
What is a 4-pipe system in relation to an AHU?
Chilled water supply and return
Hot water supply and return
2 sets of pipes for each coil (heating and cooling)
What type of glass do you need for a skylight?
LAMINATED
Which side is the cold side of the compression loop?
Evaporator
Which side is the hot side of the compression loop?
Condenser
Which is the high pressure side in the compression loop?
Condenser
Which is the low pressure side in the compression loop?
Evaporator
Arrow pointing into the pump, out from the expansion valve indicates which side?
Evaporator
Arrow pointing out of the pump, into the expansion valve indicates which side?
Condenser
Which side would be located in a cooling tower?
Condenser
Which offers the highest efficiency in solar panels? Monocrystalline or Polycrystalline?
Monocrystalline
Think M = More
Which inherently has hints of blue? Monocrystalline or polycrystalline?
Polycrystalline
Mono is black
What is the opposite of a thermal break?
Thermal bridge
What is conduction?
Heat transfer through a solid
Insulation, thermal breaks, R-value, U-vale, conductivity, resistivity, compact building forms
What is Convection?
Heat transfer through air
Air tightness, ventilation, heat carried through ductwork
What is Radiation?
Heat transfer through electromagnetic energy exchanged between objects in view of one another
Fireplace, sunshine and shade, low-e windows, chilled beams, radiators
What are 2 examples of Convection?
Air infiltration through cracks in the building’s envelope
ERVs
What are 3 types of radiation?
Foil facing
Solar heat gain
Thermal mass
What is a type of conduction?
Thermal break
When thermal control is prioritized - which HVAC system?
FCUs, Ducted w VAV & VRF
What is the difference between an FCU and AHU?
AHU deals with fresh air and are larger
FCUs deal with recirculated air and can be located in the room itself
What is a type of DX (Direct Expansion) HVAC system?
Window units or through-the-wall system
For historic buildings with no room for ducts?
VRF or Hydronic (chill beams & underfloor heating)
What are some energy efficient systems?
1 - central chiller and AHUs spread throughout
2 - renewables
3 - waste-heat capturing systems (VRF)
4 - economizer systems
5 - DOAS (dedicated outdoor air systems)
6 - all electric
7 - radiant systems
What are the quietest systems?
Remote compressors
Radiant systems
What is the best roofing for odd geometries?
Fluid-applied
Best CMU insulators from best to worst
Permite/Vermiculite
Air
Grout
‘PAG’
Best CMU to worst CMU for TL and STC
Grout
Perlite/Vermiculite
AIr
‘GPA’
What are the 2 ways to remember CMU thermal and acoustic performance?
PAG -> thermal
GPA -> acoustic
Condenser
High-pressure hot refrigerant
Compressor
Pump that circulates refrigerant
Evaporator
Low pressure cold refrigerant
Air-to-air system
Fan over condenser and evaporator
Air to Water
Fan over condenser, pumped water over evaporator
Water to Air
Pumped water over the condenser, air over the evaporator
Water to Water
Pumped water over the condenser and a different pumped water system over the evaporatorS
Split System
Condenser outside, evaporator inside (Residential)
Minisplit
Refrigerant flows through units in rooms under high pressure for heating and low pressure for cooling; can heat and cool different rooms simultaneously
Swamp cooler
Uses evaporation of water for cooling, with a fan, for very dry climates
Evaporative cool tower
Uses evaporation of water for cooling, no fan, for very dry climates only
Cooling tower
For cooling condenser water by blowing outside air over it
Chiller
Refrigeration machine for cooling chilled water in large buildings. Includes refrigerant moving through the condenser, compressor, evaporator, and expansion valve and the water that interfaces with the evaporator (and condensor)
Air-handling unit
Located down the hall, cools air for delivery to the room via ductwork
Fan Coil Unit
Located in the room, cools air by blowing it over pipes filled with chilled water from a chiller
Direct expansion (DX)
Like a window unit: with all cooling components including refrigeration machine and fan in one box
Variable vs constant cooling coil
Variable vs constant ducted air speed
Variable vs constant fan
Variable vs constant pump
How much control over the rate of flow. Variable generally offers more comfort control and more energy-efficiency, but more complex equipment
Geothermal system
More efficient because it uses the moderate temperature of earth to heat or cool water for the refrigeration machine
Chilled beams
Like radiators for coolth; measure are required to prevent condensation
What is NRC?
Average absorption coefficient across 4 octave bands
250, 500, 1000, 2000
What is absorption coefficient?
Proportion of sound reflected / proportion of sound absorbed
Why doesn’t low frequency sound reflect on small bumps?
Longer wavelength
What is STC
Sound Transmission Class
What does a higher NC rating mean?
More noise
What does you need to look for in terms of minimizing footfall noise?
Higher IIC
Impact Insulation Class
Horizontal Footcandles
Candle Power x cos0 / D^2
D = hypotenuse of triangle
Vertical Footcandles
Candle Power x sin0 / D^2
D = hypotenuse of triangle
Horizontal Footcandles is measure of light on what surface?
Measure of light on the horizontal surface
Vertical Footcandles is measure of light on what surface?
Vertical surface
