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Hvac Flashcards

1
Q

Choosing building system

A

Room for generation
General system requirements
Distribution to the spaces
Distribution to people
Fuel system
Waste or flue

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2
Q

Building systems

A

Passive systems: the shape of the building and direction of the fenestration.
And air movement: like cross ventilation or conductive currents

Usually, this is a supplement system to the HVAC

Air-based system: fan ductwork.
Moving the ward air through.
Very fast
The radiant system is slow! But it’s a pleasant feeling
Both heating and cooling for air-based system
Disadvantages: a lot of ductwork

Hydronic system: pipe, liquid that can be water.
Disadvantage: takes a lot of time to warm up the space
Pipes do not take up a lot of space

There is a combination of n of air and water-based system

Heat pump: pump valve condenser evaporates

IR system:
Infra-red system. Outdoor
Works like a toaster

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3
Q

Air-based system

A

Heater:
Hot water goes through the air-handling unit- The handling unit has a big fan to push the air through the box and room. In front of the fan, there is a cool that hot water goes through it. (Cold air goes down warm air goes up. Convection )
Fresh air and return air ducts comes to the box from behind. There is a duct for this purpose.
Then the fan pushes the air through trunk lines. Then a filter. Then branching systems.
We can add or reduce the humidity
For residential: warm air going up
Commercial: sideway process. Air is going to blow from the side

Cooling: same but cold water in pipes
How? Condenser and evaporator

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4
Q

Heater

A

Boiler
Hot water

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5
Q

What HVAC systems give you more control over temperature?

A

Multi-zone constant air volume

systems allow several ducts to serve several zones and be controlled independently with dampers. This would allow for the flexibility in temperature required by the client.

Closed-loop heat pumps
This system draws the heat from chronically overheated spaces and then distributes it to individual rooms. There is little control or flexibility in this system.

Variable air volume

Variable air volume allows for temperature to be controlled through the mixing of outside air and conditioned air per zone or room by regulating the volume of supply to the room. This makes it a versatile system.

Variable air volume reheat

Variable air volume reheat systems provide conditioned air to each zone at a constant cooler temperature, and the air is then reheated at the unit to provide temperature control at the zone or room.

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6
Q

Mufflers
Duct lining

A

Silencer
Inside duct lining for acoustic purposes.

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7
Q

Single docked, variable air volume system are more energy, efficient than constant air volume systems, because

A

The use of variable pitch blades, or variable speed signs allows air volume to be modulated from their minimum flow rate to the required demand 

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8
Q

A machine that uses a reversible compressive refrigeration loop so that both Coils may take the rule of their evaporator or condenser is

A

Heat pump

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9
Q

Evaporative condenser

A

Water is spraid over a hot pipe (cooling tower)

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10
Q

Fan coil system

A

Heating and cooling
A lot of control over temperature
Multi-family residential
Multi-tenant commercial? DX system - a lot of control
Disadvantages: how to get fresh air for windowless rooms? The fan in the room!

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11
Q

Heat pump

A

Minimal control
No duct
No pipe
Window unit

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12
Q

Chiller

A

Very large projects
A lot of control
4 loops

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13
Q

DX

A

Roof top system
Through wall system
Unitary system

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14
Q

Talk to your mechanical design that

A

you do not want your hot and cold pipes extend from the mechanical room to the building for a long distance because it’s not efficient and you will lose cool or warmth through pipes 

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15
Q

Fancy hotels

A

Central distant duct mech system

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16
Q

Mini split

A

Each zone has a thermostat built-in
Refrigerant flows
Indoor unit and outdoor unit
If you need cool air you have the condenser outside and your indoor unit is an evaporator(like a heat pump)
What if you want to have heating and cooling together?
One outside unit can be a condenser and the others can be evaporatedtors.

17
Q

Heat pump

A

The evaporator:
Cold
Low pressure

18
Q

Hydrant cooling system?

A

Chilled Beam
Radiator

19
Q

Evaporative cooling

A

Using pads water pump for spraying water in pads duct to home

20
Q

Details of a BOILER

A

Pressure release valve
Switch
Thermostat
Compression Tank
SHUT OFF Valve

21
Q

Air velocity

A

Constant or variable air velocity
Constant air velocity: all off or all on - constant air - if you want to change one degree, the source should be changed one degree. It’s not like VAV to have damper for adjusting the temperature.

Variable: variable drive motor (fam will move quicker if needed)
OR
We can have a constant volume fan but with VAV Damper!

22
Q

Cooling coil:

A

Fixed flow (all on or all off)

Variable flow which is more efficient
It opens more of the cool damper if cooking is needed. Or vs

23
Q

Number of duct

A

Single duct

Dual duct: we have both heating and cooling and we mix them according to the thermostat. Not efficient!

Ductless
Like the fan coil system
Or
Ductless mini split system
Or ductless system

24
Q

Zoned

A

Occupancy
Schedule
Solar exposure
Air quality
Core perimeter

25
Q

Room equipment

A

AHU
FCU
DX
radiator
radiant floor or ceiling
Chilled beam

26
Q

Evaporator

A

chilled water
Direct to room with fan
swamp cooler

27
Q

water to the water system
(Rooftop units) which is a chiller
Big buildings
Large projects
Because water can carry more hear or cool through distance
Do we ha a basement one?

A

it has a chiller which is a refrigerator machine a cooling tower and a compressor on the roof it has cold water pipes through all the floors and each floor has an air handling unit which has a fan over the cold pipe and makes the room cool down.

In basement one, we will have the machine which includes a cold coil and hot coil in the basement and a cooling tower on the roof/ or into the ground.

28
Q

Remote water to water system

A

there is a big chiller which has a cold coil and a hot coil. The hot coil is the water that goes to the cooling tower and the cold water in the cool coil can go to two buildings through pipes and the refrigerant is water. This cool water goes to each floor and each floor has air handling unit which has a fan over cool water pipe and this air handling units has ducts everywhere 

In this case, the cooling tower can be very far from the buildings

29
Q

Can you have the cooling tower in the basement

A

No

30
Q

What is water to air system?

A

they have the cold coil inside air handling units with a fan over it which pressurizes the air toward ducts that are located on the roof and then ducts come from the air handling unit to ward all floors.
Cooling tower condenser and compressor are on the roof.

31
Q

split system quiet inside, but does not have a scale to large buildings with large cooling load and many zones 

A

we have the evaporator and condenser split from each other and extend it as far as a hundred feet
then the evaporator or the condenser, which is inside a room will go through air handling unit and the air handling unit has dogs that distribute the cold or hot air everywhere 

32
Q

Air to air system
not as efficient as water to water system for large buildings 

A

condenser and evaporator both can be in the same room, but separated by a wall. evaporator can be blown by a fan through ducts and distribute all over

33
Q

Window unit or DX or unitary system

A

Thermal control
Not very efficient
No duct
Lots of noise
A lot of equipment and maintenance
Not easily hidden from facad

34
Q

Heat pump

A

Reversible coils
Heating and cooling

35
Q

what do we mean when we say a single zone?
Vs VAV

A

After we talked about air to air system, air to water system, water to water system

now we are talking about the distribution system
distribution system can be single zone or
BAV with terminale, reheat or without terminal reheat,

The Air handling unit (AHU) will be in all zones. Each zone has its own ahu that’s why we call it a single zone. Because in VAV we have one ahu for multiple zones.

Chiller: the cold pipe waters go through each zone to reach to the each zone’s ahu (single zone, not efficient for large building because a lot of equipment is needed).

36
Q

Is vav with terminal rehear efficient

A

No! But very good thermal control

37
Q

Constant air is more efficient od vci?

A

Variable
Because in CAV if you want to higher the temp one degree, the entire source should be higher than one degree.

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