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Oil Furnace Random lockout

padquarelli Member Posts: 3
I have a Fresh Air 80 oil furnace driving me nuts. It has a becket AF burner and a Tjerlund SS2 power vent. It ran fine for 15 years but now is doing random lockout. I had a company come in and they came about 10 times before I told them no more. Replaced most everything on the burner with no luck. Gun, igniter, control, transformer. As a test We then replace the entire burner with an older Know good becket we had from an old furnace and still no luck. We took apart the Tjerlund for a full cleaning and function test and still get lockout. All filters are clean and have been replaced. Next we are moving the oil supply line from the bottom to the top just in case something is plugging the outlet randomly. Any ideas on what else could possibly be the issue.


  • Jon_blaney
    Jon_blaney Member Posts: 134
    Tell us more about your fuel setup.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,301
    edited April 2020
    You have to figure out where in the cycle it's locking out. Is it during the run cycle, during start up, etc.
    The fact that you replaced the entire burner and still locking out means I'd be more suspect of the power venter.
    But I'd also make sure the burner was set up properly, combustion was correct, and the heat exchanger wasn't cracked.
    Power venter can create too much draft, pulling the flame off the end cone, causing a lockout.
    2 other options:
    1. Put a ProMaxx primary on there and check the error codes.
    2. Haven't done this in years, put an OnWatch on. It hooks up to and monitors every component, and data logs. The only problem with this approach is the OnWatch technology has never been updated so it requires a Windows Vista to hook into and read, unless you want to try to look on it's display and view one line of data at a time-impossible for comparing.
    The other problem with the OnWatch is it requires a adapters to hook it up to a computer-needs a 9 pin to usb.
  • BDR529
    BDR529 Member Posts: 197
    Check tube to the proving switch?
  • DZoro
    DZoro Member Posts: 1,048
    Sounds like you changed everything except the fuel, and the fuel line. Has it been checked for water? Bacteria? Sludge. Has anyone put any additive in the tank? Line tested for leaks.
    Yes power venter certainly can be a issue also.
  • padquarelli
    padquarelli Member Posts: 3
    Thanks for all the replies. Fuel is indoor oil tank tapped in the button going through filter unit prior to pump. Fuel is our next target. Moving fuel draw from bottom to through the top a few inches off the bottom to eliminate sludge or water issues.
    I see someone mentioned cracked heat exchanger. Would that cause drafting issues and cause flame not to start?
    As far as where in the cycle. As far as we can tell it randomly locks on initial call for heat. So flame not starting or Not getting sensed. Cad cell has been replaced.
    We have no access to instruments to put on the unit. I wish someone rented them locally. Now that’s it’s warm out the pressure of needing heat is gone and it’s become more of a challenge to figure it out.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,301
    Without tools and proper experience, you're just guessing. With tools and proper experience, you could find the problem quicker.
    Where are you located? Maybe someone on here can help.
  • padquarelli
    padquarelli Member Posts: 3
    I am in Mayfield NY
    EBEBRATT-Ed Member Posts: 10,235

    Tell me the service company was there 10 times and never put test equipment on it or took a combustion test????
  • Jamie Hall
    Jamie Hall Member Posts: 17,025


    Tell me the service company was there 10 times and never put test equipment on it or took a combustion test????

    Good parts changers up that way...

    Surely there is someone in the Schenectady area who has combustion and other test equipment? It's not that far out in the woods.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    HVACNUT Member Posts: 4,187
    If you're getting free gravity flow from a bottom fed tank, then that's not the issue. And if there was a suction leak you would see it.

    I agree with the other guys that the power vent needs to be looked at closer. At not by any of the previous so called techs. Anyone can blindly change parts.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 2,355
    edited May 2020
    If I remember correctly I had a customer with a similar problem. Nuisance lockouts were caused by the pressure switch on the power vent system. If wired the way my customer's control was wired, the reset button on the primary would trip if the pressure switch did not prove airflow. Everything was working fine except the pressure hose was placed on a 1/4" steel tube that was never cleaned.

    A partially blocked tube was corrected over the years by adjusting greater airflow from the power vent. As time went on the blockage got worse. Finally when the airflow was adjusted to fully open... and the pressure switch would not be powerful enough to overcome the partial blockage. the lockouts could not be resolved. When the wind hit the power vent at a certain direction, the air pressure, the partial blockage, and maybe some other factors would all align to cause the pressure switch to fail to close on random starts, and the reset on the primary would trip.

    This particular 1/4" steel tube was bent on an angle about 6 to 8" in. I finally solved it by forcing high-pressure air from a nitrogen regulator piped with fittings to a mechanical connection (not a handheld trigger). At 200 psi and by forcing a wire in the tube from the other end (disassembly of the outside fan may be required to access the other side of the 1/4" steel tube). I finally cleared the blockage and was able to correct the power vent fan setting to a more efficient adjustment. I put a note on the wall indicating that "Nuisance lockout may be caused by a blocked tube and that a pipe cleaner should be run thru the sample tube every maintenance service"
    Edward Young
    Retired HVAC Contractor from So. Jersey Shore.
    Cleaned & services first oil heating system at age 16
    EBEBRATT-Ed Member Posts: 10,235
    @Jamie Hall

    Don't know anything about Schenectady but I worked in Albany a little bit and it was horrific some of the work I saw. From what I have seen MA & CT are much better. They have no statewide licensing (if it is still that way) they have county licenses i think.