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weil mclain ultra 155 setting help?

eugdeugd Posts: 7Member
My boiler keeps on modulating all the time ever since it had its latest maintenance.
The boiler was maintained in August 2018 full cleaning and changing of all the gaskets by a contractor. Now boiler is modulating when heat demand is needed and not producing heat enough heat. Except hot water through a indirect tank available any time. it is a three zone system but both zones of baseboard heating house is hit or miss during times of heat demand since the maintenance and boiler modulates several times during the day. With no errors codes given to show or anything under the error menu. Both Sensors were replaced on the return and supply to rule-out faulty equipment. Air bleed the zones does not resolve the issues or manual restart does not stop the modulation and start the heating process. the boiler does not state any error codes but will show many several auto restart counter values. I have a question about the circulator settings under the boiler priority menu, for boiler priority only pump 1 is on, for boiler priority 2 pump two is on and for boiler priority both pump two and three are on. attached are pictures of the boiler to see the setup and a few pictures programming fields of the any help would be greatly appreciated.


  • eugdeugd Posts: 7Member
  • HVACNUTHVACNUT Posts: 2,184Member
    I was gonna say maybe the tech adjusted the ODR parameters but target temp is 190 so its probably not connected.
    Temp diff is good through the boiler but its running both DHW and space heat.
    Priority pump 1 on for DHW priority. Pumps 2 and 3 priority off for space heat.
    Do you mean short cycling rather than modulation?
    What's the temp diff through the boiler with the space heat running only? Run them separately and together. Write it down.
    Those soft lockouts could be supply and return temps too close or return temp too high.
    Has anyone checked the supply and return temps on the space heat circuits because it seems like it is air bound.
  • eugdeugd Posts: 7Member
    I think the technician had no clue about my boiler and it’s setting even though he said he did. When he left my kids were scolding there hands with hot water because he must of reset back to factory settings. Thankfully he picked up his phone after he left to talk me through how to lower the hot water temp. Ill shut off pumps and post the results tonight. Thanks for your response
  • eugdeugd Posts: 7Member
    I called Weil-McLain tech support today. Lucly spoke with someone who went over settings on the boiler even though I’m not a plumber. Turns out the guy that came over and serviced the boiler did not turn on all the pumps i priority 2 and 3 and set my limiting temp at 190 instead of 180 for the baseboard. As a result the boiler was fighting itself with the pumps by pushing and pulling out of sequence resulting in the boiler cooling it self for prolonged durations. Now it’s much quieter and keeping the fist floor warmer at least for now. Thanks for all the information
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