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Stinky Furnace Exhaust

Cthomas's picture

My furnace exhaust smells pretty bad - sort of an organic smell.  Honestly it smells a bit like propane and rotten grass, or bad toe-jam, or really bad morning breath.


Its a natural gas 90+ efficiency with separate intake and exhaust PVC runs to the outside of the home through the rim joist.


I looked at the flame last night and it was bright blue, so no combustion issues.  The motor and blower seem to be working great.


Anyone have any ideas?


I suppose the next step is to take the exhaust run apart and make sure no little critters crawled in there - but it's all glued up, so I thought I would post here first...


Thanks in advance...

(post #115597, reply #1 of 23)

Is there a screen on the end of the exhaust run to keep vermin out? Kind of wondering how you are smellng the exhaust, isn't it away from living space?

                            Mike


    Small wheel turn by the fire and rod, big wheel turn by the grace of god.

                            Mike

    Small wheel turn by the fire and rod, big wheel turn by the grace of god.

(post #115597, reply #7 of 23)

I was thinking the same thing, and no.  No screen.  (Thus, who knows what type of critter took up residence in there over the summer.)


The exhaust ends up outside on the back of the home under a deck landing.  It's been smelly all winter so far.  Seems to be getting worse.


PVC is cheap, so maybe I will just take it all apart and look inside.  The total run is about 20 feet.


I did think about the water, but with the furnace running and the exhaust being warm, any moisture would evaportate...


 


Thanks for the thoughts!


 


 

(post #115597, reply #8 of 23)

So this is a new smell.


disconnect at the furnace and hookup the shop vac to suck it clean!

(post #115597, reply #9 of 23)

if you think that you truly got something in there stinking,you have a much bigger problem that needs to be dealt with quickly.


that is if it' s block you could get c.o. in the house! i'd get on this pretty quick and see.


if a man speaks in the forest,and there's not a woman to hear him,is he still wrong?

the older i get ,

the more people tick me off

(post #115597, reply #10 of 23)

The exhaust ends up outside on the back of the home under a deck landing.  It's been smelly all winter so far.  Seems to be getting worse.


Aside from the smell, your exhaust is probably located in an exclusion zone. If you have the installation or owners manual, there should be drawings showing where the exhaust pipe can not be located.


While I doubt you will spent much time on your deck during the winter months, the wrong location can cause the gasses to carried into your home by eddie currents and drafts. That is why there are exclusion zones around windows, door, soffets, and decks.


You may even find the drawings on the manufacturers web sit, or contact them and they will send them to you. Play it safe with your families health.

(post #115597, reply #11 of 23)

Propane or natural gas?


The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #115597, reply #12 of 23)

Forgot to ask that.


Walked by a big trailer parked in our lot this morning. The exhaust from the propane fuel generator definitely stinks a bunch more than natural gas.

(post #115597, reply #13 of 23)

Hey, you geared up for an ICE event? Looking nasty headed our way later.

Spheramid Enterprises Architectural Woodworks


Repairs, Remodeling, Restorations


 


They kill Prophets, for Profits.


 


 

www.richmondrenovationsandrestoration.com  

(post #115597, reply #17 of 23)

Looks like the big ice storm missed us. Kind of split and went north and south of us. I think you all got more than we did.


I think our contractor spread more salt on the parking lot than the total accumulation of ice in the whole metro area.


Iike walkin on marbles, and our back entrance has a white "skid mark" all the way to the elevators. That stuff is great on a parque floor.

(post #115597, reply #18 of 23)

We are getting an freezing rain storm tomorrow. With any "luck" you might be it around Saturday.

When I went to Speed I had coop twice at Allis Chalmers in Milwaukee.

I remember the same more salt than snow conditions.

.
William the Geezer, the sequel to Billy the Kid - Shoe
. William the Geezer, the sequel to Billy the Kid - Shoe

(post #115597, reply #21 of 23)

With any "luck" you might be it around Saturday.


Gee, thanks for that Bill. I'm on call untill after the holidays. Means I could spending some not so quality time away from the family this season.


BTW, welcom back.

(post #115597, reply #22 of 23)

With the welcome back I will stand outside tomorrow fanning some plywood to try and deflect the storm.

But my aim is not that good.

.
William the Geezer, the sequel to Billy the Kid - Shoe
. William the Geezer, the sequel to Billy the Kid - Shoe

(post #115597, reply #23 of 23)

Furnace update:


Turns out the secondary heat exchanger was shot.  I am now the proud owner of a   97% efficient, variable speed, modulating burner...


Maybe I should put racing stripes on it?


Thanks to all for the insight.  What a great Christmas present...

(post #115597, reply #14 of 23)

For a 90%+ unit to operate properly, the gas leaving the heat exchanger below its dew point so water will condense out in the heat exchanger and it will continue to condense out as it passes through the exhaust line because it continues to cool. It will be wet inside every time the furnace runs. This is perfectly normal but the exhaust line must be installed so it drains back to the furnace without low spots that will trap water.

(post #115597, reply #15 of 23)

"I did think about the water, but with the furnace running and the exhaust being warm, any moisture would evaportate..."


No.

(post #115597, reply #2 of 23)

before i started dissassembling pvc,unless it's a really short run, i would look at getting a sewr guy out there to run a camera thru there. you can buy one but they are pretty expensive.

if a man speaks in the forest,and there's not a woman to hear him,is he still wrong?

the older i get ,

the more people tick me off

(post #115597, reply #3 of 23)

They do put out a fair amount of water. Maybe you have a low spot that's not draining?

(post #115597, reply #4 of 23)

They do smell nasty! My Dad in the UK said the same thing about his 90%+ unit.

(post #115597, reply #5 of 23)

Is this a new install? If not, has it always been like this? Was it set-up with instruments or "plug-n-pray"?


I've smelled what seemed like burning rubber and it goes away. Figured it was some PVC filings left in the pipe.

(post #115597, reply #6 of 23)

Propane or natural gas? If propane, check to see if your tank is empty.

Did the unit just fire up for the first time this winter? It'll take several hours of running time to burn off the odors that seem to accumulate while it's shut down.


The mark of the immature man is that he wants to die nobly for a cause, while the mark of a mature man is that he wants to live humbly for one. --Wilhelm Stekel


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

(post #115597, reply #16 of 23)

When I have stinky exhaust, my wife says it's bad gas.

Spheramid Enterprises Architectural Woodworks


Repairs, Remodeling, Restorations


 


They kill Prophets, for Profits.


 


 

www.richmondrenovationsandrestoration.com  

(post #115597, reply #19 of 23)

Many commercial gas supplies come "odorized" so that if there's a leak, you'll be able to smell it. Natural gas and propane are odorless. Usually they put a bit of H2S or sulfur containing organics in called "thiols" which smell and when burned could possibly be the source of your odor.

(post #115597, reply #20 of 23)

As mentioned, likely a low spot in the exhaust flue and nasties growing in the condensate.

>>I looked at the flame last night and it was bright blue, so no combustion issues.

For the record, flame color does not indicate quality of combustion - I've tested plenty of "blue flames" with CO output ay too high.





"Ask not what the world needs. Ask what makes you come alive... then go do it. Because what the world needs is people who have come alive."

Howard Thurman

======================================== "Man's capacity for justice makes democracy possible, but man's inclination to injustice makes democracy necessary." Reinhold Niebuhr: 'The Children of Light and the Children of Darkness' http://rjw-progressive.blogspot.com/ ========================================