Condensing Boiler Vent Freeze up

Tom Giedraitis

I've questioned why the contractor that installed my munchkin vented across my basement and through a sidewall instead of running the vent pipe straight up through the house either in a wall or up the old chimney.
The reason he cited is that he has had through the roof condensing boiler vents ice over. I find this a bit hard to believe, but wanted to ask the experts here.
The the job was done about a year ago, and since I'm doing renovations which would make running the vent straight up very easy, I'd perfer to do that rather than have that exhaust blowing steam which freezes up on the side of my house and surely is'nt prolonging the life of my shingle siding. Not to mention it looks lousy.

Was my installer's concern legit, or blowing smoke because he wanted to get done the quickest and cheapest way?

I'm located in northern nj

Kal Row

most velocity is best...

shorter is less drag form pipe friction and gravity


best way is to come out of the unit and step up from 3" to 4" and go out the side real short, and put a cone outside that steps it back down to 3" or even 2-1/2 - the jet causes the steam, to kind of disappear into the atmosphere - works for me

you can also try terminating the jet inside the middle and center of a 2ft open 5" tube so that you get venturi mixing

if I have a head on wind problem then I put an up/down tee at end

sd_3

boiler freeze

i have a two-pipe steam heating system with an oil burner. the whole system froze in winter. some experts said there is no point in checking the boiler, just replace because it is certain to be cracked, some say a steam boiler cannot freeze and crack because it is not completely filled with water. is it worthwhile checking it out or not?

Rich Kontny_2

I herd

that if you live in a area that is well below freezing most of the winter its best to used two pipes instead of the
concentric.

Reason hot humid air mixes with the cold air and it reaches
it dew point,then you get water dripping at the outlet of
the exhaust,reach will and does freeze.
Two pipe out the side is a better choice in colder climate.
Made not be as purdy,but it will not keep out the burner on
the pressure switch.

As for the boiler freezing and being crack,I would have to
believe about the boiler not being crack,just as you said
because of the boiler not being full of water.

But why is there a issue,fill it with water and see if it
leaks.If it does not leak,bring it back down to proper water line in fire it up,then she if she start blowing any steam up the chimney.

One last dance maybe??