I had a Heating contractor install a Utica Trifire 4 section three pass boiler and Superstor 45 gallon DHW over the summer. The boiler AHRI rating is 79 MBH
The Boiler vents into a tile lined 8X8 chimney that is on an exterior wall and is in perfect condition. Old Dunkirk boiler had a stack temp of nearly 450 degrees and the chimney never had condensation issues.
Now the heating season has arrived I notice condensation plumes leaving the chimney any time the boiler is running. The other day when it was 35 degrees out I went on the roof and removed the chimney cap and noticed that the top clay tile liner was completly wet and condensation was dripping back into the chimney.
The combustion report listed the Gross stack temp of the new boiler at 380 degrees. Should I have the contractor remove the 3rd pass baffles and re adjust combustion to try to get the stack temp up another 60 to 80 degrees to limit or stop the amount of condensation in chimney? I understand that I will loose about 2% efficiency but I would we willing to if it will save a perfectly good chimney and avoid a Stainless steel liner install this year.
Boiler has a Taco PC 700-2 outdoor reset and I have the boiler MIN set to 150 degrees and Design set to 180 degrees. This time of year the boiler seems to be short cycling with a 2.5 minute run time with a 5.5 minute idle time during a continuous call for heat from thermostat. The Differential on the PC700 is set to auto and when Boil target is 161 degrees the controller swings the boiler from 170 to 151 I am sure some of the condensation issue is with the short run time followed by the 5 minute idle time allowing the chimney to never really reach a good operating temperature but hope an extra 60 to 80 degrees in stack temp will help.