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Furnace Runs Continuously, Despite Thermostat

dcmcgrain Member Posts: 2
Hello all,

Very amateur here. I have a Riello40 with tiger loop. Hot air, no water or steam. Yesterday our heat was out. After trying a number of troubleshooting items - oil filter, fuel nozzle, clogged line, we were able to diagnose that the line (top draw) was sitting all the way into the bottom of the oil tank and pulling up water/sludge. We pulled the line up a few inches as a temporary fix and ran fine.

Tonight, just woke up to very warm temperatures. Thermostat says were at 70, with setting at 65. Thermostat says all equipment is off, but burning is running full blast and so is fan. Even turning the thermostat to off didn't work. To shut the system down I had to cut power to the burner itself.

Obviously very disconcerting. Any help or suggestions? I'm betting a sensor or something in the Riello40 computer is wonky?


  • Jamie Hall
    Jamie Hall Member Posts: 22,162
    Sounds like something I had recently -- and that a relay in the boiler burner control box is hanging up. Get a technician in there and have them check it.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Douglocal638
    Douglocal638 Member Posts: 3
    You bumped into something by mistake like wiring from the thermostat check that first it’s low voltage wiring see if you see small wires touching each other some where, or the thermostat is bad take thermostat off the wall and see if it shuts down
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,378
    You need to get a tech in there.
    You need to see if power is being sent to the control box when it should not be sending power. If it is not, then it's the control box or the base plate wiring. If it is, it's the board.
    After you changed the nozzle you are suppose to do a full combustion test/analysis-draft, smoke, etc.
  • DZoro
    DZoro Member Posts: 1,048
    Agree with Steve, make sure the tech confirms your safety limits are working correctly. They should kill power to the burner.
  • dcmcgrain
    dcmcgrain Member Posts: 2
    Appreciate all the advice. Will be working on a tech this week.

    This morning, when it wasn't 3am anymore, I noticed that it appeared the control box was sitting out perhaps a mm or two. I removed it and re-positioned flush. Has been working appropriately with the thermostat since, though I'm leary. Thinking it could have been a connection not flush?

    Still calling that tech.
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,378
    Could be, as long as all your safeties check out.