Ahhh winter in the midwest, don’t ya just love it? Put a few logs on the old fire and enjoy a nice evening in front of the hearth, until what to my delicate nose should appear, but the smell of eight dead reindeer ! I mean the smell is absolutely dreadful, you know, like too many hot chicken wings and beer last night ? So I could only imagine that some little critter cozied himself up next to the heat inside the wall and got hisself cremated. It seemed logical to cut a couple holes in the wall and see what was back there, but found no evidence of extraterrestrials whatsoever. On the odd chance that a bird had gotten through the chimney cap and nested above the flue I went up the chimney with smoke and mirrors and found nothing. And then just to make the little lady happy had a chimney sweep clean up behind me. Anyway, his take on the situation was that the exhaust from our water heater was too close to the fireplace chimney (they are side by side and the furnace is vented elsewhere) and combustion gasses were being sucked back into the house. But as inquiring minds want to know, how is this possible when heat rises? Is the solution as simple as raising the water heater exhaust a foot above the firelace chimney?
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The downside
would be if you were back drafting the water heater and the fumes didn't even make it up the flue b/4 they came back in.
Where's the water heater? Do you have a carbon monoxide alarm that works in that house?
Yeah, I don't see how water heater exhaust could be drafting down the chimney when a fire's burning. And water heater exhaust should be odorless.
But it may be that the fireplace creates enough of a vacuum in the house to draw in odors from somewhere. If there's a dead mouse in a wall somewhere you might not notice it until the fire's burning and drawing air through a nearby electrical outlet.
Try opening a window in the room (when a fire's burning) and see if that seems to make the odor stop coming in.
I can't imagine propane or nat. gas smelling like rotting animals, but I don't deal much with either.
And I don't understand the point about the exhaust being close to the chimney and getting sucked back in. A chimney is for sending gases out, not in. Like you say, heat rises; nothing traveling up a chimney should end up back in the house. If it did, my house would reek of creosote.
Does the smell only happen when a fire is going?
A fireplace can have substantial 'suction pressure' that can backdraft furnace or water heater ... regardless of where they are located. Heat rises, but suction sucks (too early to choose better words). If your house happens to be a little on the tight side, the path of least resistance to air going up your fireplace ... is the flues of other devices or even exhaust fans (bath, kitchen).
Agree, though that backdrafting the other devices ... assuming clean combustion should not necessarily be smelly. Maybe you are sucking in from some other big gap in your house construction and there is a dead critter ... that could be anywhere ... but maybe the strength of the smell is your clue to the location.
Could also be sucking air through a dry sewer trap, maybe a floor drain that's been "forgotten".
stinkin' fireplace
thanks to all you guys for taking the time to address my smelly situation. The next step is going to be starting a fire and turning off the water heater. If that does not rectify the situation, then I will search further as I can identify the smell emanating from the room directly behind the fireplace (where I initially looked inside the wall)...perhaps I will find a little "free lunch" ready to eat after all. I should further explain that this is an interior fireplace in a 1930's house and the water heater shares the same chimney, though in separate chambers of course. There is no tile lining inside the chimney and the vent pipe is within 6 inches of the fireplace stack, both are covered. I do have a carbon monoxide detector in the same room as the fireplace and of course the water heater is located in the basement which does not have any odor of the sewer line. I will post another update, hopefully with news that doesn't stink.
stinky follow-up
Well guys, it would appear that we have found the problem (though only tested this once) and it does in fact have to do with back drafting, that allusive term that doesn't really seem to make sense to me, but I guess my thoughts are now up the chimney and around the corner...and apparently right back down again. With a fire going and the water heater turned off, the offensive odor was not present , and within 15 minutes of turning it back on the smell started to recur. Perhaps there is an air leak between the two chimneys that is drawing air into the house since there is little smell in the basement where the water heater is located, who knows. For now, opening a window quickly solves the problem. So hopefully the ultimate solution will be to raise the exhaust stack well above the fireplace chimney, but that will have to wait for warmer weather, which here in Iowa could be awhile. Thanks again for your ijnput, now I have some weinies to roast on the fire......
I suspect what happens is that when you shut down the water heater you provide a source for a downdraft to compensate for the updraft in the fireplace. This reduces the vacuum that would otherwise pull in the odor from wherever it's coming from.
Probably when the water heater is running and not the fireplace the fireplace is backdrafting.
james
Seems odd it would pull down the chimney to where you can smell it as that heated air from the fireplace is going up-causing the need for makeup air...........it's getting from somewhere.
I'd be wondering if its stink from somewhere else that's only activated when both the heater and fireplace run at the same time-increasing the need for makeup air. You open the window and that alleviates the draw from the stink area...............wherever that is.
In liquids, you'd introduce dye. Anyway to introduce smashed garlic near the burner on the water heater?
>>>Seems odd it would pull
>>>Seems odd it would pull down the chimney to where you can smell it as that heated air from the fireplace is going up-causing the need for makeup air...........it's getting from somewhere.
That's what I've always thought.
I'm guessin' this experiment isn't over.
If not, I'd like to hear the result....I love a puzzler.
One possible solution would be to go with a chimney exhaust fan. There are lots of options for them on the web if you google it.
http://www.lindemannchimney.com/Chimney-Fans.html
http://www.fireplacemall.com/Chimney_Caps/Exhausto_Fans/exhausto_fans.html
-Andrew
I'm betting an exhaust fan would make a bad problem worse.
Think the exhaust fan would make it smell worse in the house? I can't imagine how it would. Although, it isn't something I would go with until i found out the exact reason of the occurence and determined an exhaust fan to be a cheaper or easier way to safely make it work in place of tearing down the chimney or something.
The fan would increase the vacuum and draw in more odor. (Note that in this case the fan that was mentioned is a fan to augment the fireplace draft, but the odor increase would occur with any exhaust fan.)
Keep us posted on this--I really, really doubt that you've found the whole answer yet.
For starters, gas WH's just don't stink in the way you've described. Also, the stench from the WH would more readily enter thru the chimney at times when no fire is burning in the firelplace. And it seems to me that, for the fireplace chimney to reverse its flow, more than just buoyancy of the flue and chimney exhaust must be acting on the flow--something mechanical, like exhaust fans or the furnace blower must be part of the action.
if the fireplace reversed its flow, wouldn't the room be full of smoke? Can't believe that is the issue. Don't know if this relates but propane has a way of eating away at masonry over time and really should be vented through a pipe or liner. Did the Chimney Sweep have a look inside the wh flue? Sometimes it gets clogged at the bottom with mansory residue and affects the draft, maybe pulling in makeup air from elsewhere. Just a wag.
good luck