The smell is driving me nuts......

[hivacer]

Is the unit level? Does the drain have a trap and a vent after the trap? I would really like to take a look at this.

[J-HITMAN]

You have two issues
1. A draft that should not be.
2. A smell that should not be.
Have what ever dampers needed to be installed installed and get that system balanced or repaired. While doing this tell them to locate and inspect all duct work have everything sealed up nice. This will not only save you from the smell but save you money. You should not have air moving through the ducts while the unit is off unless you have some type of a problem. Can you describe the layout for supply and returns with unit location and duct material and location?

I was called out to repair some duct under a crawle space and also a funny smell! well i got to repairing the duct and i noticed I was laying in a pool of dead possum! the possum got stuck in the duct and died! It smells like dirty sock? yes! clean the coils, fan, and return air duct! Also stop putting the dirty close hamper infront of the return air!!!!!! lol!!!

[charlezz]

Thanks for the response hivacer...I believe the unit is level. There is a trap and vent...would this be to stop the sewer gas smell? I believe someone else asked this question when they came out. I live in Clovis California.

[J-HITMAN]

After you take a shower? i wounder if its a stink pipe on the roof clogged up?
then the smell is coming out of you drains? well, Thats what the traps are for>??? where is the condensate draining? get the stink pipe checked and make sure the roofers didnt drop a coke bottle down the pipe.?

[JBM1000]

9 out 10 times it's sheet rock dust from non caring sanding crew and even if you tried they don't give a ****. You end up getting the stale wet powder caking your everything. Only real remedy is total 100% rip it all out and do it again.

[mark beiser]

Replace the indoor coil with a new coated coil.

[charlezz]

Thanks for the replies guys...

Mark, do you mean replace the cooling coil? Sorry, not in the business and not exactly sure of all the terms.

Hitman, the condensate pan has a drain that comes out the unit and is attached to a pipe that goes down the inside of the house. I am thinking this is one of the sewer lines. Not exactly sure if this is what the line is called.

Thanks

[bluestone]

Charlezz, I'm not an HVAC tech, but I am a builder. HVAC guys have mostly been looking at this from their side although they have touched on a possible cause.
You say the condensate pipes go down the inside of the house, If they are cut into the DWV vent and not properly trapped or poorly installed the odor may be from the sewer system (not a good thing).
Also you say it happens after the shower fan has been run, leads me back to the bathroom. If the house becomes depressurized when the HVAC system is on and the fan vent, DWV stack or both are near a soffit, ridge, or gable vent, these exhausts may be entering the HVAC and being blown into the conditioned space. (not my first choice but possible).
More likely the first scenario because if you are running warm water in the DWV system vapors will rise and be brought up by the chimney effect of the DWV stack.
Hope this helps, what is it Sherlock Holmes says? If all obvious choices have been exhausted, the answer is the least obvious no matter how implausible.

[propmanage]

I thought you already checked the drain ?

[marvin]

post # 19 says this is a lennox dual pac. with an rtu why would the
condensate be piped back into the house? if it is
dropped into a vent & the condensate trap is dry it
could very well suck in odor from the vent. try repiping to
the edge of roof

[smokin68]

post # 19 says this is a lennox dual pac. with an rtu why would the
condensate be piped back into the house? if it is
dropped into a vent & the condensate trap is dry it
could very well suck in odor from the vent. try repiping to
the edge of roof

Here is the likely culprit. Good catch. However, piping to side of house could be against code. When the shower is run, the shower trap fills up with waste water, and the odor goes out the vent stack along with the sewer gas. If the condensate is piped to this at the roof level and it's trap is empty, unless it's a positive pressure trap it's going to mix that smell in with the supply air. The way the condensate line is run sounds like your entire problem......