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Navien tankless propane combination boiler water heater

Batash13 Member Posts: 2
a couple of times in the last week we’ve noticed the outside exhaust pipe cover/grate (the one I’m assuming keeps pests out) on the outside boiler exhaust has blown out and landed all the way in the neighbors yard...also we have smelled very faint hints of propane inside the house...the smell seems to go away oddly enough when we crank the heat in the second basement heating zone...we had the propane company out to check for leaks and they tested the system and replaced the outside pressure regulator but they also suggested we relocate the inside pressure regulator as they said the boiler is pulling a strong demand of propane so the regulator should be further away from it...currently it’s right next to the unit...not sure if it’s related to the exhaust cap blowing off or the faint/occasional indoor propane smell. Could be two separate issues but just concerned. I have a call in to our hvac person but wanted to do some research and try to get some answers before he came as to what might cause such strong pressure inside an exhaust pipe that would blow off a pest prevention cover grate for outside exhaust and a faint propane smell inside when downstairs heat is shut off...seems really odd to me...Worth noting this is a brand new unit installed about 3 months ago and this all just started...any help is greatly appreciated.


  • Ironman
    Ironman Member Posts: 6,900
    Was a combustion analysis done with a digital analyzer?
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Batash13
    Batash13 Member Posts: 2

    I’m not sure to be honest. We had the installer here today. He didn’t notice anything wrong (of course the smell of propane wasn’t there when he was here) but it comes and goes. The smell is definitely coming from inside the unit and goes away when there is a high demand for hot water and heat in the second zone.