HVAC - Piped Distribution Systems -Video Flashcards
What are the types of Steam Distribution Systems?
Single Pipe Systems and Dual Pipe Systems
What are the types of Hydronic Distribution Systems?
2 pipe steam systems, 4 pipe steam systems, constant volume systems, variable volume systems
What are types of Refrigerant Systems?
2 pipe systems, 3 pipe systems,
What is a single pipe system?
Uses same piping to supply the steam and return the condensates. Older system generally not used anymore. Individual radiators cannot be shut off in a heating cycle as that would trap the condensate. They can’t be modulated through controls - only through pipe sizing and air vents.
What is a TRV?
Thermostatic Radiator Valve - modulates the steam flow in radiators.
What is a 2 pipe system?
Uses a pipe to supply the steam and another pipe to return the condensate. Steam pipe flow adjustments can be made at individual radiators. Can use a condensate pump when gravity does not suffice to return flow.
What is a 2 pipe hydronic system?
Can be either direct or return reverse systems. Primary unit can be a boiler or a chiller and sends to a convector. The convector can be a radiator, heating/cooling coil, fan coil unit, air handler unit, or other secondary device. To modulate the system, valves with actuators at the convectors/terminal devices.
What is VFD or CFD?
Variable or Constant devices on circulators can modulate the flow in the system.
What is a water source heat pump system?
This is a 2 pipe hydronic system that is a direct only system. It can do heating and cooling at the same time, an exception to the 2 pipe hydronic system.
What is a 4 pipe hydronic system?
Have a cold supply and a cold return and a hot supply and a hot return. At the end of the cold supply/return is a chiller and at the end of the hot supply/return is a boiler. They can be modulated with two-way valves. Heating and cooling can happen simultaneously.
What is a 3 pipe hydronic system?
Provides 1 hot, 1 cold, and 1 neutral temperature loop and are limited to WSHP systems.
What are the advantages and disadvantages of 2 VS 4 pipe systems?
Advantages - Can provide heating and cooling to different zones, greater comfort, and automatically changes over. 2 pipe requires manual changes. Disadvantages - 2x more expensive and requires additional space
What is a constant volume hydronic system?
3 way valve provides mixed supply temperature or by-passes a portion of the hydronic (water) supply in order to provide a variable heat flow to control the amount of heat addition or subtraction to a zone in the building.
What is a sensor control in a constant volume system?
The mixing position of a 3 way valve in constant volume system is controlled by a room temperature sensor.
What is a variable volume hydronic system?
A 2 way valve is used to modulate flow in order to control the amount of heat transfer. This requires a variable pump system. Savings can be achieved by converting a constant pump to a variable pump and creating a by-pass to a replaced 2 way valve with a 3 way valve.
