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Oil boiler to Lochinvar Noble Natural gas combi boiler

bob eck
bob eck Member Posts: 930
Lochinvar Noble combi boiler natural gas replacing a 41 year old steel oil boiler with domestic coil.
System is one zone with cast iron radiators. My father in-laws house. I told him the radiators should not get as hot as they used to with the oil boiler as it sent 180 degree water to the radiators. With the large cast iron radiators the system should not need more than 160 F supply water temp on closest day / night.
Question for the professionals. As this boiler was running and my installing partner had it on high fire to test it with his Testo kit I was outside and the vent seemed noisy but the boiler is very quiet inside. (One of my customers installed a Burnham K2FT Firetube 155C combi boiler that is noisy inside and has a quiet vent outside. He just installed a Lochinvar Noble 150 combi and that boiler is quiet inside and has a noisy vent outside. Why are these boilers like that?) Now this vent is sidewall two pipe with flush termination fitting about 18” off the ground. I have a Triangle Tube PE110 in my house natural gas with a concentric PVC vent termination that is 8’ Off the ground because of a public sidewalk. My vent seems quiet or is that because it is so high in the air. My PE110 is very quiet inside.


  • Leon82
    Leon82 Member Posts: 684
    I'm not sure if the vent length has anything to do with it but my whn called for a 12 foot minimum vent length.

    If it is for this is for sound or combustion stability I don't know
  • NY_Rob
    NY_Rob Member Posts: 1,370
    edited October 2017
    Nice install! The press fittings look great.

    I think the mod-con exhausts are a bit noisy because they're wide open right into the HX assembly. Kind of like a car with straight pipes :o
    Some mod-cons draw their combustion air from an outdoor intake pipe that terminates in the boiler cabinet- that air is then drawn in to the open inducer fan located in another part of the cabinet with no direct or sealed connection between the two... that can produce noise from inside the cabinet vs. coming from the exhaust pipe. Two different systems, two different noises.

    Love the fact that your father in-law has CI radiators.... perfect fit with a low-mass mod-con.
  • Ironman
    Ironman Member Posts: 7,397
    Is it "fog-horning" from the vent when the boiler's running at low to mid range modulation?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.