HVACopediaNoritz · Tankless water heater
F76 Multi-system communication error
What the control is telling you
Communication error between two quick-connected units.
Applies to: All Noritz residential tankless with quick connect (EZ, NRCR, NCC199CDV, NRC/NRCP)
Likely causes
- More than one remote control connected on a quick-connect pair
- Units are not the same model
- Quick connect cord problem
Test and repair steps
- Connect only one remote controller when two units are quick connected.
- Make sure both units are the same model (required to quick connect).
- Check the quick connect cord and connectors.
Settings for these units
- Indoor clearances (required and recommended) · Noritz NRCR
- Operation panel menu settings and defaults · Noritz EZ, Noritz NRCR
- Water quality limits · Noritz EZ, Noritz NRCR
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Source: Noritz EZ/NRCR/CDV Level 2 Maintenance & Troubleshooting (Premix R2 V2), 73 & F76 error codes, p.15; Noritz Residential Level 2 Maintenance & Troubleshooting (NRC/NRCP and older, R2 V1), 73 & F76 error codes, p.9. Summarized in our own words; check the original manual for your model.
Homeowner looking at this code? See what it means for you and when to call a technician.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.