# Smell coming from all floor registers.



## John_W (Nov 3, 2009)

*Maybe it was a cat - but not recently.*

It may be that a cat got into the crawlspace this past winter and its only now that I'm smelling it because the humidity has gone up so much.

I'm still puzzled about why/how the smell comes out through the floor registers. I'm sure the urine is not inside the duct work. I guess a little urine smell goes a long way - somehow managing to get sucked into what seems to be a very tight system.


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## gena (Jan 6, 2008)

2,000 square foot ranch and a single return?! Am I missing something?


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## yuri (Nov 29, 2008)

Lots of ammonia smell comes from cat urine. I would try an experiment. Go to Safeway or a pharmacy or HDepot and get that highly concentrated Nilodor product which is in drops in a small bottle. Use 1 or 2 in those puddles and wait to see if the smell gets sucked into the house. My installers use silicone where the air filter attaches to the furnace etc and even a small leak on those joints if not siliconed can suck in a smell.
http://www.petmarket.com/nilodor-tapadrop-p-1340.html


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## John_W (Nov 3, 2009)

yuri said:


> Lots of ammonia smell comes from cat urine. I would try an experiment. Go to Safeway or a pharmacy or HDepot and get that highly concentrated Nilodor product which is in drops in a small bottle. Use 1 or 2 in those puddles and wait to see if the smell gets sucked into the house. My installers use silicone where the air filter attaches to the furnace etc and even a small leak on those joints if not siliconed can suck in a smell.
> http://www.petmarket.com/nilodor-tapadrop-p-1340.html



Yuri,

Thanks for the tip. I will get some and try it.


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## John_W (Nov 3, 2009)

gena said:


> 2,000 square foot ranch and a single return?! Am I missing something?


1,800 square feet in the house proper use that return. There is another 200 square foot room, in the garage, that has its own return back to the main return.

Since the Goodman rep increased the blower speed, the grill you see makes a singing sound. Even with the grill removed, there is still a rumble from the constriction (choke point picture is attached) where the air passes through the floor.

The original contractor set the blower to a lower speed to minimize both noises. Last fall, the Goodman rep helped us with another problem, but also checked all the DIP switch settings. He said two of them were wrong and he changed them. The result was a greatly increased air flow rate, and a return of the grill noises.

The original contractor should have increased that opening through the floor. There were other troubles with him, and we have gone to a new company for our service work.


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## tpolk (Nov 7, 2009)

wet insulation has ammonia smell


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## Thurman (Feb 9, 2009)

Mr. Polk gets the "Cupie" doll, IMO. John-you state that you are in AL. which I will take to be Alabama= high humidity this time of year as it is here. I fought this exact same problem some years back and found it to be high humidity under the home. I have plastic on the ground and was finding puddles of water directly under the main A/C lines but not the return line (yes, gena-one return for a 1960 sq.ft. living space home). Further investigation found that all of my insulation was wet and dripping from humidity-cold air vs. warmer high humidity air under the home. At that time a friend of mine who does HVAC work got me a squirrel-cage type fan from a split unit and we adapted it to fit one of my foundation vents. I wired this in on timer to run twice a day to bring in air from outside. This air may be high in humidity but is dryer than what is under the house after testing with hydrometers. So-new A/C duct insulation, running the vent fan two times/24 hrs. solved that problem and got rid of some mold on my floor joists. Now there are two businesses in my area that go under homes and put de-humidifiers under there to control humidity under the home. David


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## beenthere (Oct 11, 2008)

Seal the crawlspace. Install a small portable dehumidifier in the crawlspace. With a hose to drain outside. 
Set it for 55%RH. It won't have to run often. And will also prevent moisture from getting into the house.


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## Marbledust (Jun 26, 2010)

You can reduce the noise in your grilles by upgrading to a new type of vent cover
the ones you have are stamped steel with and open area of 3/8"
change over to the bar type grille that as more free air space


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## ScreamingMimi (Aug 7, 2015)

I've got the same problem. Stink from the vents and the furnace. I have no AC. I've read people saying the insulation underneath is wet, either from a leak or even mice getting in. But not the vents or furnace. I have an HVAC guy coming next week


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