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Weil-Mclain Ultra Series 3 Boiler Cycles on and Off Repeatedly
My three-year-old Ultra Series 3 boiler never reaches its target temperatures on either the DHW or heat priorities. It ignites, runs for a minute or two at its maximum modulation (set to 70%), goes down to its minimum (set to 30%), then shuts off for a minute or two. It then repeats the process over and over.
Meanwhile the input and output water temperatures never get above 110 degrees even though they are set for 160 and 140, respectively. Is there any other possiblility than that the control module has gone bad?