Navien Tankless Water Heater: Set up a cascade (assign main and sub units)
Set up a cascade (assign main and sub units) on a Navien tankless water heater: Two heaters are paired from their front panels; the main unit shows MA.00 and the sub unit SL.01.
Applies to: NPN-160U/180U/199U, NPN-120E/160E/180E/199E
How to fix set up a cascade (assign main and sub units): step by step
- Main unit: hold Diagnostic + Up (+) for more than 5 s; MA.00 appears.
- Sub unit: hold Diagnostic + Down (-) for more than 2 s; SL.01 appears.
- Main unit: hold Diagnostic + Up (+) for 5 s again; displays return to temperature.
If the unit shows an error code, look it up: Navien Tankless Water Heater codes
Models
NPN-120ENPN-160ENPN-160UNPN-180ENPN-180UNPN-199ENPN-199U
Source: Navien NPN-U/NPN-E Installation Manual, 5.2.1 Configuring the Communication Settings, p.58. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.