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Rinnai heater not turning on

I use a Rinnai heater for both DHW and floor heating in an 800 Sq ft cottage. Has worked great for 7 years, but now when the thermostat calls for heat, the circulating pump comes on, but the heater does not come. Still working fine for DHW. Any suggestions?


  • Jamie Hall
    Jamie Hall Member Posts: 22,922
    It still fires up OK for domestic hot water? Then it's not really the Rinnai, but a problem with the command from the thermostat to the circulator to the boiler.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England