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Utica UB90-100 Series 4 Problem

Jake_K Member Posts: 2
Hello All,
I would like to start by saying I have spoke with Utica tech support 3 times and they are unable to tell me what the issue is.
I have been helping a friend, and I wish I hadn't. I am working on the Utica UB90-100 Series 4 boiler. It runs for long periods always ends up dropping out, but not on limit, and does its post purge. The boiler then trys to restart and goes through pre purge, then the ignitor (Brand new, already went through that thought process, this boiler uses flame rectification through the ignitor.) glows in the sight glass for the correct 20 seconds, then the valve light comes on and I have 27 volts steady through the gas valve, and flame visible in the glass. Now the problem begins. It runs for about 5 seconds then goes to post purge. Recycles and the same thing happens until the integrated boiler control blinks valve. The inducer motor is louder than I would like but is creating enough pressure to satisfy the pressure switches. I have tested the switches with my manometer made for testing the switches and they are both working, closing at positive 1.75 inWc and the other at .5 inWc. Blower pulls -2.2 inWc to -2.6 inWc. 

I can't seem to get a straight answer from tech support, and have RTFM over many times and I'm stumped. One tech support says clean the heat exchangers to flush out aluminum oxide. Did that. The next says change ignitor. Did that. The next has me jump passed the hydrolevel LWCO/Limit control. Did that. The other says "That blower sounds loud, I would change that. Didn't do that. 

I'm very frustrated with the tech support and am not going to just start throwing parts at the thing. According to my manometer the blower meets the requirements.

I'm ready to tell him to get rid of it simply because of tech supports lack of a straight away answer. And frankly some of them are rude.

Any help is appreciated, thank you.


  • Jake_K
    Jake_K Member Posts: 2
    And oh yes.... I have the proper 2.5 inWc from at the burner in case someone was going to suggest testing that. Forgot to mention that.
  • Ironman
    Ironman Member Posts: 7,397
    Your description suggests that the board is not see the flame. Make sure that you have good ground connections in the boiler and all the way back to the electric panel.

    Can you measure the flame signal?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    EBEBRATT-Ed Member Posts: 15,829

    You have to put your meter in series to read the flame signal usually. best with an analog meter.
  • hot_rod
    hot_rod Member Posts: 22,467
    Does the gas pressure stay at 2.5” after it lights off?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,166
    I wonder if the Utica boiler folks monitor this forum like Roger? I don't remember ever seeing an EK problem go unsolved here. But they have fewer problems.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Purseon
    Purseon Member Posts: 4
    Curious if this ever got solved. I have the same boiler, same exact problem.