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Build my nuts in your face > HVAC System > Flashcards

HVAC System Flashcards

1
Q

HVAC?

A

heating ventilation air conditioning

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2
Q

what are hvac designed for

A
  • thermal conditions
  • adequate amount of outdoor air
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3
Q

what does a hvac system consist of

A
  • controls
  • min of one fan to move air
  • provision for introducing outdoor air
  • filter
  • coil for heat and cooling air
  • distribution system
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4
Q

why is the location of air intakes important

A
  • because of the potential to permit contaminates from the area
  • usually 1/3 up building
  • usually found next to loading docks or on roofs near exhausts
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5
Q

what is the mixing plenum

A
  • it is where return and outdoor air mix
  • since rain and snow can be sucked in there should be floor drain
  • if drain is connected to sewer line must have water trap
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5
Q

what is a outdoor air damper?

A

opens and closes to control air volume passing through inlet

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6
Q

what do air filters do?

A

they deliver clean air

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6
Q

what do the coils in the hvac system do

A

either cool or heat air coming in

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7
Q

what is the purpose of cooling coils

A
  • cool air
  • dehumidify air as water condenses
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8
Q

what is purpose of heating coils

A
  • heat the air
  • provide thermal comfort
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9
Q

where must coils be?

A
  • accessible
  • clean
  • have sufficient capacity to give thermal comfort
  • located centrally throughout building
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10
Q

what are condensate drain pans for?

A
  • collect moisture under cooling coils
  • must be properly sloped towards the drain line
  • should be kept clean
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11
Q

what is the supply air fans

A

the driving force to distribute air into building

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12
Q
A
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13
Q

return-air fan, what do, what is?

A
  • draws air out of building and deliver it to air-handling unit and exhausted outside
  • relationship to air supply is important as resulting pressure can introduce air into air-handling unit
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14
Q

boiler?

A
  • generates heated water for thermal conditioning and hot-water needs
  • fossil fuels or electric
  • generate combustion products that may become indoor contaminants
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15
Q

chilllers

A
  • provide chilled water to meet cooling loads
  • required for thermal comfortable conditions
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16
Q

hvac system produce what?

A
  • heating
  • cooling
  • heat transfer fluids
  • control delivery to a space to maintain stable condition
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17
Q

heating and cooling produced by what

A
  • refrigeration devices
  • furnaces
  • boilers
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18
Q

movement of heat transfer fluids are preformed by what?

A
  • ductwork
  • grillers
  • diffusers for air
  • pumps
  • piping system for water
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19
Q

name a heating and cooling control device

A

space thermostat

20
Q

heating and cooling system, explain them

A
  • very temp of air supply with a constant flow
  • vary flow of air supply with constant temp
  • vary flow and temp of air supply
21
Q

what is a zone?

A
  • one area that is controlled by a single thermostat
22
Q

single zone system

A

house with furnace controlled by a single thermostat

23
Q

two zone system

A

house with two furnaces each controlled by a separate thermostat

24
Q

two types of hvac controls, which is better

A
  • manual
  • automatic
  • automatic controls system more precisely and reliably for comfort, safety, and efficiency
25
Q

the control systmes control?

A
  • temp sensor
  • pressure sensor
  • flow rate sensor
  • humidity sensor
  • speed sensor
  • time with clock sensor
26
Q

what are basic control devices?

A
  • sensor
  • controllers
  • actuators
27
Q

sensors?

A
  • measure and monitor variables
  • signals are input into controller
28
Q

controller?

A
  • provide decision for function of control system
  • determines if signal is sent or not
29
Q

actuators?

A

provides physical control of equipment by valves or dampers

30
Q

thermostats?

A

sense and respond to temp
- signals sensors and controller

31
Q

humidistats?

A

sense and respond to humidity
- either relative or absolute

32
Q

constant temp variable volume?

A
  • used for zone control
  • simple residential system, maintains the temp set on thermostat
  • turns of when the temp is achieved
33
Q

single zone constant air volume

A
  • simple system used in commercial building
  • fans run constantly and provide ventilation
  • air is supplied at a constant rate, to achieve the desired temp
34
Q

cooling coil uses what to cool?

A
  • refrigerant
  • cold water
35
Q

how does heat get produced by hvac system?

A
  • furnace and space heater heat air
  • fuels burnt to heat water or produce steam to heat air
  • electric heat up coil to heat air
  • boilers heat by hot water or steam
36
Q

air-handling system components

A
  • fan sections,
  • cooling section
  • heating section
  • humidification section
  • filter section
  • air mixing section
  • discharge air plenum
  • other components
37
Q

what is contaminates are in outdoor air?

A
  • gas, liquid, solid particles
  • bacteria
  • viruses
38
Q

fans in hvac system

A

moves air in the system either ventilate heat or cool
- all have rotating impeller blades, increases kinetic energy of air
- increase of energy is converted into pressure

39
Q

ductwork includes

A
  • supply duct
  • return duct
  • outside air
  • relief air
  • exhaust air ducts
40
Q

ducts made from what material?

A
  • galvanized steel
  • aluminum
  • stainless steel
41
Q

what shapes can ducts be?

A
  • rectangular
  • round or flat oval
42
Q

how does insulation in a duct work?

A
  • applied to interior of duct (rectangle)
  • applied external as fiberglass or blanket (round)
  • external more expensive
  • for thermal and acoustic
43
Q

rectangular duct used for what?

A
  • used for low-velocity applications
44
Q

round or flat oval used for what?

A
  • medium high velocity
45
Q

what do air devices do?

A

supply and remove air from building

46
Q

name air devices?

A
  • diffusers
  • grilles
  • registers
47
Q

what are diffusers for?

A
  • to get rid of any drafts areas creating hot or cold spots
  • it controls air quantity and direction
48
Q

what is the coanda effect?

A
  • allows air to fall gradually and mix with room air ver large area
  • without this the chilled air will fall straight to the ground creating a cold spot
  • this is called dumping creating uncomfortable draft

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