DeDietrich C230 ECO-A 120 Installation, Operating And Service Manual page 16

4 Installation
Connection
Flow
Return
Gas connection
Condensate drain
Combustion air supply
Flue gas outlet
Dimension "A" 
16
Dimensions
Fig. 2 Elevation drawings
C230 ECO-A 80/120/160/200
2" NPT thread (do not remove the adapter, pipe is non-NPT)
2" NPT thread (do not remove the adapter, pipe is non-NPT)
2" NPT thread (do not remove the adapter, pipe is non-NPT)
 1.26" (32 mm) external
 5.91" (150 mm)

 5.91" (150 mm)
52½" (1330 mm)
C230 ECO-A