HVAC System Examples and Configuration Solutions

 

Examples of typical HVAC systems, including photos, appropriate Asset Score field entries, and common  configuration issues and solution options appear below.  

 

Typical HVAC Systems – Air Handlers

                                                                   

 Packaged Rooftop Unit (RTU) – rooftop air conditioner used in conjunction  with either  a gas fired furnace or electric resistance heating.
Enter the following:
 Distribution Equipment: Air Handler
 Cooling Source: Direct Expansion Coil (Central DX)
 Heating Source: Central Furnace (gas or electric)
 Fan Control: Constant or Variable Volume (CAV/VAV)
 Zone Distribution Type: Typically Single Zone; may be entered as Multiple Zone with Reheat  Terminals Units.  
Visit  Small,  Large,  and Very Large Commercial Package Air Conditioners and Heat Pumps and  Commercial  Warm  Air Furnaces for information on DOE Efficiency Standards for these types of equipment.  
 Packaged Rooftop Heat Pump – rooftop heat pump that provides  high-efficiency heating  and cooling performance in one self-contained unit. Typically range from 2-ton to 20-ton capacity.
Enter the following:
 Distribution Equipment: Air Handler
 Cooling Source: Direct Expansion Coil (Central DX)
 Heating Source: Heat Pump (electric)
 Fan Control: Constant or Variable Volume (CAV/VAV)
 Zone Distribution Type: Single Zone  
Visit  Small,  Large,  and Very Large Commercial Package Air Conditioners and Heat Pumps for information on DOE Efficiency  Standards for this type of equipment.  
 Central Plant Chiller/Boiler – air handling unit with chilled water  supplied through  an on-site central chiller, and hot water provided by an on-site central boiler.


 
Enter the following:  Distribution Equipment: Air Handler
 Cooling Source: Plant – Chiller
 Heating Source: Plant – Boiler
 Fan Control: Constant or Variable Volume (CAV/VAV)
 Zone Distribution Type: Single Zone or Multiple Zone with Reheat Terminals Units  
Visit  Commercial  Packaged Boilers for information on DOE Efficiency Standards for this type of equipment.  

 

Typical HVAC Systems – Zone Equipment

                                                                                       

 Window Through-the -Wall Air Conditioner – small sized units (typically 1-5  tons)  which sit in a window or wall opening, with interior controls.
Enter the following:
 System Type: Window Air Conditioners
 Distribution Equipment: Zone
 Cooling Source: Direct Expansion Coil (Terminal DX)
 Heating Source: No Heating
 Fan Control: Constant Volume (default)
 Zone Distribution Type: N/A  
Visit  Packaged  Terminal Air Conditioners and Heat Pumps for information on DOE Efficiency Standards for this type  of  equipment.  
 Packaged Terminal Air Conditioner (PTAC) with Furnace – direct expansion  coil unit  used in conjunction with either a gas fired furnace or electric resistance heating.
Enter the following:
 System Type: Packaged Terminal Air Conditioners
 Distribution Equipment: Zone
 Cooling Source: Direct Expansion Coil (Terminal DX)
 Heating Source: Single Zone Central Furnace (gas or electric)
 Fan Control: Constant Volume (default)
 Zone Distribution Type: N/A  
Visit  Packaged  Terminal Air Conditioners and Heat Pumps for information on DOE Efficiency Standards for this type  of  equipment.  
 Packaged Terminal Heat Pumps (PTHP) – window or through-the-wall space  conditioning  unit providing both cooling and heating.
Enter the following:
 System Type: Packaged Terminal Heat Pump
 Distribution Equipment: Zone
 Cooling Source: Direct Expansion Coil (Terminal DX)
 Heating Source: Heat Pump (electric)
 Fan Control: Constant Volume (default)
 Zone Distribution Type: N/A  
Visit  Packaged  Terminal Air Conditioners and Heat Pumps for information on DOE Efficiency Standards for this type  of  equipment.  
 Unit Heaters – self-contained fan-type heaters designed to be installed  within the  heated space such as rooms or garages.
    Enter the following:
 Distribution Equipment: Zone
 Cooling Source: No Cooling
 Heating Source: Single Zone Central Furnace (gas or electric)
 Fan Control: Constant Volume (default)
 Zone Distribution Type: N/A  
Visit  Unit  Heaters  for information on DOE Efficiency Standards for this type of equipment.  

   



HVAC System Configuration Solutions

 

Issue 1:  Different types of heating and/or cooling equipment serve different sections of a building.

 

  • Example: Section A of a building is served by a chiller, and Section B is served by a roof  top  air conditioner.
  • Solution: Create two separate blocks and assign an Air Handler with "Plant – Chiller" as  the  Cooling Source to Section A, and an Air Handler with "Central DX" as the Cooling Source to Section B.

 

Issue 2:  A building uses one major heating and/or cooling system, but also uses supplemental heating or cooling  equipment.

 

  • Example: A building is served by both a central plant boiler and baseboard heaters.
  • Solution: Presently, Asset Score supports convective baseboards as a secondary heating and cooling system.  Create one of the following primary Zone Equipment HVAC system types: Window Air Conditioner, Packaged Terminal Air Conditioner (PTAC), or Four Pipe Fan Coil Unit (FPFCU). Create a baseboard by selecting Baseboard from the System Type selection for Zone Equipment. Assign both Zone Equipement systems to a block. Select the block and enter a Secondary heating fraction.

 

Issue 3:  One type of heating or cooling source serves a building with multiple pieces of equipment of various vintages,  efficiencies and capacities. 

  • Example: A building with four rooftop air conditioner units, all with different ages (1990,  1995,  2000, 2000), coefficients of performance (COP) (2, 3, 3, 3), and capacity (6, 10, 12, 12).
  • Solution: Enter an Air Handler with Central DX selected; the year of the largest or majority  piece  of equipment; four pieces of equipment, the efficiency (COP) using a weighted average based on equipment size,  and  the average output capacity. For example:
    •  Year of Manufacture: 2000
    •  (Note: If the equipment efficiency is entered, the year of manufacture will not be used by the model).  
    •  # Pieces of Equipment: 4
    •  Efficiency (COP): 2.85
    •  (2 COP * 6 Tons) + (3 COP * 10 Tons) + (3 COP * 12 Tons) + (3 COP * 12 Tons)/(6+10+12+12)
    •  Average Output Capacity (tons): 10

Issue 4:  Buildings use heating and/or cooling systems that are not listed as available heating/cooling sources in the  Asset  Scoring Tool.

  • Example: Building A is an apartment is served by central plant boiler with radiators, and  Building  B is a hotel with Packaged Terminal Air Conditioners (PTAC) in each of its 50 rooms.
  • Solution: Presently, the Asset Scoring Tool does not include options for radiators. To  accommodate  these options: for Building A, create and assign an Air Handler with "Plant – Boiler" as the Heating  Source;  "Multiple Zone" as the Distribution Type, and "Reheat" as the Terminal Unit. For Building B, create and assign  Zone  Equipment with "Terminal DX" as the Cooling Source, and "Single Zone Central Furnace" as the Heating Source, and  enter "50" in both of the "# Pieces of Equipment" fields