nti tft 085 fault code 99 exceeds 28v

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duffy_4
duffy_4 Posts: 84
in Radiant Heating

any ideas on solution for this,boiler is 6 years old no problems during that time,doing in floor heat via warmboard multi zoned with buffer tank and 80 gal indirect,here in chicago. incoming voltage is 128 across both phases at 100 amp panel im getting 28v on low voltage side of boiler,tried new transformer…no help.anyone else have this issue.got com ed come out they sat everything is with in specs.looking and trying a power conditioner or a step down buck boost transformer.thanks for your help

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  • 109A_5
    109A_5 Posts: 4,759

    " incoming voltage is 128 across both phases at 100 amp panel im getting 28v on low voltage side of boiler "

    Well 128 VAC seem a bit high for 120 VAC nominal, hopefully you don't have an intermittent poor neutral connection with the utility service.

    So you are reading 28 VAC if it gets to 28.1 it makes a fault code ? That margin is a bit close.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    GGross
  • duffy_4
    duffy_4 Posts: 84

    Yes exactly,reading 27.8 to 28.5 on low voltage at board and 128vac incoming,reset boiler tries start faults out few times the lockout.

  • hot_rod
    hot_rod Posts: 28,699

    Have you tried a second meter to be sure it is not the meter?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • 109A_5
    109A_5 Posts: 4,759

    As much as I agree with a second opinion (second meter), the boiler's behavior seems to support what the meter is reading or the meter's reading seems to support what the boiler is doing.

    I'd try to get the utility the correct the voltage. The utility has various means to correct the voltage, maybe there is a piece of equipment that is 'Out of Service' and once it is restored the voltage will go back to normal. They just don't want to tell you they have a defect. Also (informational) if you are friendly with your neighbors maybe see what their voltage is also, same transformer as yours and maybe others on the street too.

    If you must correct the issue yourself (as you mentioned) a transformer wired to Buck would probably work. For example a 120 VAC primary to 6.3 VAC secondary would drop the 128 down to about 121.7. However sadly you would be constantly paying the utility for a small bit of extra power to run the Buck transformer.

    A power conditioner depending on what it actually does inside may not change the Voltage (like surge / spike protection only) or if it is like a constant voltage transformer type it may noticeably raise your electric bill since they often run warm.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    GGross
  • hot_rod
    hot_rod Posts: 28,699

    The power provider may put a data logger on your system to determine if it is a transformer issue, capture spikes, etc. I would start with them.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • pecmsg
    pecmsg Posts: 7,634
    https://forum.heatinghelp.com/discussion/comment/1905959#Comment_1905959

    Are the times this happens loged? Same time, morning evening night time.

  • duffy_4
    duffy_4 Posts: 84

    Boiler won't fire based on fault code so it's consisted 128v input ...28v out on boiler ond from comed

  • duffy_4
    duffy_4 Posts: 84

    CommonwealthCommonwealth Ed. Came out and checked the voltage into the unit and said it was all within range and nothing they could do. I will check with the other tenants first floor and third floor to see if they're reading the same thing. This is the first building off the main transformer on that block.

  • 109A_5
    109A_5 Posts: 4,759
    edited October 11

    If the utility measured 128 VAC, you need to complain louder, that is exceeding their standards. Get them to explain their standards to you.

    image.png
    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • duffy_4
    duffy_4 Posts: 84

    I know called, Ed Commonwealth Edison to come out and check it out. I think twice and they said it was all within standards so I'm going to try that. Buck transformer one day this week. See what that does. Thanks for your input

  • 109A_5
    109A_5 Posts: 4,759

    I'd want to see their measurements, or they don't know their own specifications / standards.

    I see no benefit to running the voltage right at the upper limit. Unless maybe there is a piece of the utility's equipment that is 'Out of Service' and once it is restored the voltage will go back to normal. Maybe they just don't want to tell you they have a defect.

    A Buck transformer is not hard to do, however you should not have to. And you are paying for their nonsense.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    GGross

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