Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.

If you've found help here, check back in to let us know how everything worked out.
It's a great way to thank those who helped you.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Gas boiler burner shuts off within a minute for no reason

Ted89Ted89 Member Posts: 21
I have a newish Trio boiler with a Carlin gas EZ burner, indirect DHW tank, HydroStat 3250 plus base control, and a Tekmar 260 outdoor reset control. Working fine for 4 years. Lately, the burner seems to go on a lot with only domestic hot water demand and no space heat baseboard demand. Looking more closely, I see the burner comes on sometimes (not always) for just a minute, then shuts off, only to repeat many times until it stays on. Even when the burner turns off before demand or high limit is met, the Tekmar displays the burner icon indicating the switch is activated for the burner to light (but doesn't). The Tekmar #11 and 12 burner switch terminations correctly indicate continuity when the burner icon is shown.

Nothing to do with the Warm Weather Shutdown or Unoccupied mode. There must be a sensor somewhere doing this?!

What could to causing this? Thanks for any suggestions to check.

Ted

Comments

  • JUGHNEJUGHNE Member Posts: 6,622
    My first guess would be flame sensor.
    If you try space heating you may get the same burner cycling if it is a flame sensor.
  • ZmanZman Member Posts: 5,595
    You might try temporarily jumping the tekmar connections to eliminate the possibility of a flaky switch. If that is not the case, it sounds like the flame is not proving in the Carlin.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • HVACNUTHVACNUT Member Posts: 3,036
    Seems like its going into recycle, proving flame then dropping out and then it begins a new trial for ignition.
    When was the last time it was serviced and had a combustion test?
    Just curious, the 3250 Plus offers ODR. Why the Tekmar?
  • Ted89Ted89 Member Posts: 21
    Thanks for 2 great suggestions. I'll test tomorrow. How quickly would a flame sensor shut off the burner? Mine were as short as 5 seconds.
    This is only a 4 year old system. Is the sensor something I could clean? The earliest appt with my serviceman is 6 weeks. Can't take a shower.
    Thanks
  • JUGHNEJUGHNE Member Posts: 6,622
    If you have a flame rod sensor, it should be cleaned every 1-2 years.
    Scotchbrite pad would clean it up pretty good.
    It is actually one part of a 2 component electrical circuit, the other is the grounded portion which could be the burner itself.
    Both paths of conductivity have to be clean with good connections. The flame of the fire is between these 2 items and causes the electrical signal to be rectified from AC to DC.
    If your flame control does not receive that constant signal it will shut down and retry.
    Intermittent connections can cause your problem.
  • Ted89Ted89 Member Posts: 21
    Understand.
    How quickly after a burner flame start would a dirty flame sensor rod shut it down?
  • Jamie HallJamie Hall Member Posts: 12,315
    Ted89 said:

    Understand.
    How quickly after a burner flame start would a dirty flame sensor rod shut it down?

    Variable. Depends in part on just how dirty the rod is, and the characteristics (electronic) of the safety circuit.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
    JUGHNE
  • Ted89Ted89 Member Posts: 21
    Could it shut it down in as little as 10 seconds?
  • HVACNUTHVACNUT Member Posts: 3,036
    It's been 5 days. I know your service man can't get there for 6 weeks, which is utterly ridiculous, so it's time to find a new reputable HVAC contractor to repair the burner. And take out a maintenance agreement.
  • Jamie HallJamie Hall Member Posts: 12,315
    Ted89 said:

    Could it shut it down in as little as 10 seconds?

    I would think so. And as @HVACNUT says, six weeks is ridiculous. Find someone competent who can come sooner.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Ted89Ted89 Member Posts: 21
    Thanks HVACNUT
    Just re-read your firstpost asking why a Tekmar 260. I had to think a minute on that. I had the Tekmar on the previous boiler before I converted to gas 4 years ago. If a 3250 Plus can do ODR and vary the target BWT accordingly- maybe i don't need it. But can it do DHW circulator priority over the space heat circulator with 3 ZVs? I know it can't do a port-purge. Thanks again
  • HVACNUTHVACNUT Member Posts: 3,036
    @Ted89, no, the 3250 Plus does not offer post purge. It does offer thermal pre purge that will hold the burner off on a space heat call to dump stored BTU's to the emitters before firing.
    And yes, it can be wired for use with zone valves. Diagram 3 in the manual shows the end switches from the zone valves connect to TT and the circulator for the zone valves to C1,C2 on the 3250. The indirect zone gets wired through ZR,ZC on the 3250.
    Like most ODR apps, domestic priority overrides ODR and thermal pre purge.
  • Ted89Ted89 Member Posts: 21
    Thanks to all.
    Paid for the 24 hr. guy to come out. It was a dirty flame sensor. And the entire chamber had heavy black soot. Trying to find possible causes. See my post, "VERY odd soot pattern . . .". For some reason I can no longer post a reply to that thread now.
  • Ted89Ted89 Member Posts: 21
    Thanks to all.
    Paid for the 24 hr. guy to come out. It was a dirty flame sensor. And the entire chamber had heavy black soot. Trying to find possible causes. See my post, "VERY odd soot pattern . . .". For some reason I can no longer post a reply to that thread now.
  • Jamie HallJamie Hall Member Posts: 12,315
    Did your tech. measure and adjust all your combustion parameters? With instruments? It can't be done by eye. Heavy soot usually indicates that the combustion parameters are way out of whack.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • Ted89Ted89 Member Posts: 21
    Thanks to all.
    Paid for the 24 hr. guy to come out. It was a dirty flame sensor. And the entire chamber had heavy black soot. Trying to find possible causes. See my post, "VERY odd soot pattern . . .". For some reason I can n't post a reply to that thread now.
  • gennadygennady Member Posts: 776
    Why flame scanner got dirty? Why soot in the chamber? You fixing consequences, not the root of the problem.
    Gennady Tsakh



    Absolute Mechanical Co. Inc.

    www.AbsoluteMechanicalCoInc.com
  • Jamie HallJamie Hall Member Posts: 12,315
    @Ted89 -- as @gennady said, you are fixing consequences, not problems. There is something seriously wrong with that burner adjustment and setup, judging by your other thread...
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
Sign In or Register to comment.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!