Hvac Flashcards
Choosing building system
Room for generation
General system requirements
Distribution to the spaces
Distribution to people
Fuel system
Waste or flue
Building systems
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
Air-based system
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
Heater
Boiler
Hot water
What HVAC systems give you more control over temperature?
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.
Mufflers
Duct lining
Silencer
Inside duct lining for acoustic purposes.
Single docked, variable air volume system are more energy, efficient than constant air volume systems, because
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 
A machine that uses a reversible compressive refrigeration loop so that both Coils may take the rule of their evaporator or condenser is
Heat pump
Evaporative condenser
Water is spraid over a hot pipe (cooling tower)
Fan coil system
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!
Heat pump
Minimal control
No duct
No pipe
Window unit
Chiller
Very large projects
A lot of control
4 loops
DX
Roof top system
Through wall system
Unitary system
Talk to your mechanical design that
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 
Fancy hotels
Central distant duct mech system
Mini split
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.
Heat pump
The evaporator:
Cold
Low pressure
Hydrant cooling system?
Chilled Beam
Radiator
Evaporative cooling
Using pads water pump for spraying water in pads duct to home
Details of a BOILER
Pressure release valve
Switch
Thermostat
Compression Tank
SHUT OFF Valve
Air velocity
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!
Cooling coil:
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
Number of duct
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
Zoned
Occupancy
Schedule
Solar exposure
Air quality
Core perimeter
