Last week during the cold snap (of course!) our ancient boiler died, and after a week in a freezing house I got it replaced with a gas Lochinvar Cadet boiler. Our previous chimney venting was replaced with power-venting through the wall for this high efficiency boiler. The contractor I chose said it was not permissible to vent to the side (though the others had planned to) because the neighbor's driveway abuts the house, and freezing condensate might cause a safety slipping hazard. Instead they vented to the front of the house, where billowing clouds now are emitted from below the window obscuring the view and causing the neighbor to complain about the "fumes" which blow over to his front door.

I'm guessing that most of what's visible is actually water vapor, but that some carbon monoxide and other combustion biproducts are probably also present. Aside from the loss of view through my favourite window, are there any health/safety concerns, for us or the neighbor? The vent is the required distance from the window (18 inches?) but the clouds clearly come right up past it. Perhaps the invisible CO somehow dissipates more quickly than the visible water vapor? Seems like with the move to power venting this must have come up before, but my searches have not found answers.

Thanks!

rrraven, Toronto, Ontario