Niagara water heaters use standard atmospheric gas tank diagnostics. See Rheem troubleshooting for gas tank diagnostic patterns (Niagara is manufactured under contract by OEMs using similar engineering).
Niagara Troubleshooting
Niagara water heaters use standard atmospheric gas tank diagnostics. See Rheem troubleshooting for gas tank diagnostic patterns (Niagara is manufactured under contract by OEMs using similar engineering).