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.
What is a 2 pipe variable refrigerant ( VRF or VRV) system?
Can only provide heating or cooling at one time based on a master unit’s settings.
What variable refrigerant flow also known as?
VRF is also known as variable refrigerant volume (VRV)
What is a 3 pipe variable refrigerant system?
Configured with one heating pipe, one cooling pipe, and one return pipe. Limited simultaneous supply based on outdoor temperatures. Greatly affected by outdoor air temps. Compressor energy is the largest use of energy in the system. Can transfer heat from one zone to the other without turning on compressor.
VRV/VRF systems are ___ to conventional HVAC systems.
More efficient by 20-30%.
What are hybrid/combination distribution systems?
Distribution systems can be combined in different ways. Typically a central plant uses piping distribution to supply or remove heat from ducted distribution systems.
