Find an example file that is specific to the object in question.
In this example, FourPipeBeamLargeOffice.idf. Then search for the object.
The notable connections in this object are the air and water node names.
Note that there are 2 air nodes, and 2 sets of water nodes. There are no coils in this object, they are inferred.
AirTerminal:SingleDuct:ConstantVolume:FourPipeBeam,
Core_bottom 4pipe Beam, !- Name
HVACOperationSchd , !- Primary Air Availability Schedule Name
HVACOperationSchd , !- Cooling Availability Schedule Name
HVACOperationSchd , !- Heating Availability Schedule Name
Core_bottom 4pipe Beam Inlet Node Name , !- Primary Air Inlet Node Name
Core_bottom 4pipe Beam Outlet Node Name , !- Primary Air Outlet Node Name
Core_bottom 4pipe Beam CW Inlet Node , !- Chilled Water Inlet Node Name
Core_bottom 4pipe Beam CW Outlet Node , !- Chilled Water Outlet Node Name
Core_bottom 4pipe Beam HW Inlet Node , !- Hot Water Inlet Node Name
Core_bottom 4pipe Beam HW Outlet Node, !- Hot Water Outlet Node Name
AUTOSIZE , !- Design Primary Air Volume Flow Rate
AUTOSIZE , !- Design Chilled Water Volume Flow Rate
AUTOSIZE , !- Design Hot Water Volume Flow Rate
AUTOSIZE , !- Zone Total Beam Length
0.036 , !- Rated Primary Air Flow Rate per Meter
597 , !- Rated Beam Cooling Capacity per Meter
10.0 , !- Rated Cooling Room Air Chilled Water Temperature Difference
5.2E-5 , !- Rated Chilled Water Volume Flow Rate per Meter
CapModFuncOfTempDiff, !- Beam Cooling Capacity Temperature Difference Modification Factor Curve or Table Name
CoolCapModFuncOfSAFlow, !- Beam Cooling Capacity Air Flow Modification Factor Curve or Table Name
CapModFuncOfWaterFlow, !- Beam Cooling Capacity Chilled Water Flow Modification Factor Curve or Table Name
1548 , !- Rated Beam Heating Capacity per Meter
27.8, !- Rated Heating Room Air Hot Water Temperature Difference
5.2E-5, !- Rated Hot Water Volume Flow Rate per Meter
CapModFuncOfTempDiff, !- Beam Heating Capacity Temperature Difference Modification Factor Curve or Table Name
HeatCapModFuncOfSAFlow, !- Beam Heating Capacity Air Flow Modification Factor Curve or Table Name
CapModFuncOfWaterFlow; !- Beam Heating Capacity Hot Water Flow Modification Factor Curve or Table Name
Now look at the induction unit example file. 5ZoneFPIU.idf.
This objects has 3 air nodes, 2 sets of water nodes, and a mixer object.
AirTerminal:SingleDuct:ConstantVolume:FourPipeInduction,
SPACE1-1 FPIU, !- Name
ReheatCoilAvailSched, !- Availability Schedule Name
autosize, !- Maximum Total Air Flow Rate {m3/s}
1.0, !- Induction Ratio
SPACE1-1 ATU Supply Node,!- Supply Air Inlet Node Name
SPACE1-1 ATU Induc Node, !- Induced Air Inlet Node Name
SPACE1-1 In Node, !- Air Outlet Node Name
SPACE1-1 HW Coil Water In Node, !- Hot Water Inlet Node Name
SPACE1-1 CW Coil Water In Node, !- Cold Water Inlet Node Name
Coil:Heating:Water, !- Heating Coil Object Type
SPACE1-1 HW Coil, !- Heating Coil Name
autosize, !- Maximum Hot Water Flow Rate {m3/s}
0.0, !- Minimum Hot Water Flow Rate {m3/s}
0.002, !- Heating Convergence Tolerance
Coil:Cooling:Water, !- Cooling Coil Object Type
SPACE1-1 CW Coil, !- Cooling Coil Name
autosize, !- Maximum Cold Water Flow Rate {m3/s}
0.0, !- Minimum Cold Water Flow Rate {m3/s}
0.002, !- Cooling Convergence Tolerance
SPACE1-1 ATU Mixer; !- Zone Mixer Name
Here's how I would make this change.
Using a text editor:
1) find the coils and mixer ... (more)
How many replacements of terminal units are we talking about here? It'd do it manually (leveraging search and replace in my text editor as much as possible) if it's a handful. It you have say 50 of them, I'd probably script it (using Python and Eppy)
Not sure if the task is as easy as doing a search and replace. Looks like FourPipeBeam needs additional components such as a return plenum. Which we do not get with the designbuilder induction unit model. It seems tedious to reconnect all the nodes and add components.