Sewer Smell at Front A/C

[Birchwood]

Had a new Dometic Penquin installed in our bedroom a few months ago and often it blows
a sewer smell.Am trying to understand why this occurs as it should be just cooling the
interior air and not drawing air from the exterior where the vents could be interferring.
I think this issue was mentioned before in another thread and curious if anyone has
found a solution to this problem?A Dometic repair person checked the install and assured
me the smell would disappear over time as its associated with the breakin period.I have been
using the A/C daily for the last 2 months and sometimes it still smells.

 

[westxsrt10]

It may be time to fix it yourself, the units are not 100% sealed between the intake air and discharged air chambers. Try removing the 4 interior ceiling flanged screws and remove the filter section. Look inside the unit and seal any signs of light or gaps entering from the outside. Be sure to keep the filter clean so it dosn't suck in attic gases. Try that first, there are other ways the smell can enter your RV.

 

[mikeandconnie]

We also had a Sewer smell with our 2009 Pinhurst, after repairing the vents and installing extreme vent the smell from the ac went away. Here a link.
//heartlandowners.org/showthread.ph...-Sewer-Gas-Smell-after-vent-pipe-repair/page3

 

[Birchwood]

I reviewed some of the past threads on this issue and the responses vary widely from studor valves to gaps in the
A/C install.I am leaning toward a smell entering the area between the ceiling and roof as I am convinced the A/C should not
draw air from the outside.It shouldn't matter what smells are in the roof area they should not go into the A/C.
My task will be to check for short vent pipes that allow odor into the attic

 

[hoefler]

Remove the inside trim, and look up in the cavity and see if it is sealed off from the attic. If it is not, the whole area is the return for the A/C. It will draw air from the attic, the attic will pull air in from the attic vent AND the sewer vents. The sewer vents are not sealed from the attic, they stick up through the roof, then the vent collar is installed around it, the the cap is installed. Air is drawn in around the vent, back into the attic, and into the A/C. When the second A/C is installed, the attic is suppose to have block outs installed from the roof to the ceiling, then caulked for an air tight seal.

 

[wdk450]

Gang:
I don't think this is what is the problem for the poster, but I wanted to put this important message out.

Yesterday, I was working under the sink fixing that "water shutting off from the faucet under high flows" problem that I have had with the trailer since day one. It involved a lot of body contortions getting up and under the back side of the sink. I started to smell an awful "sewer" smell that I haven't had recently. Add to that the fact that the black/grey tanks are empty. After about a half hour I discovered that I had inadvertently turned one of the stove burners on part way. That "sewer smell" was PROPANE!!! I had the door open and turned on the fantastic fan to clear the air.

 

[cookie]

I started to smell an awful "sewer" smell that I haven't had recently. Add to that the fact that the black/grey tanks are empty. After about a half hour I discovered that I had inadvertently turned one of the stove burners on part way. That "sewer smell" was PROPANE!!!

Good point to bring up. I had the same thing happen. Thought it was sewer but turned out to be LP.

Peace
Dave

 

[Birchwood]

Gang:
I don't think this is what is the problem for the poster, but I wanted to put this important message out.

Yesterday, I was working under the sink fixing that "water shutting off from the faucet under high flows" problem that I have had with the trailer since day one. It involved a lot of body contortions getting up and under the back side of the sink. I started to smell an awful "sewer" smell that I haven't had recently. Add to that the fact that the black/grey tanks are empty. After about a half hour I discovered that I had inadvertently turned one of the stove burners on part way. That "sewer smell" was PROPANE!!! I had the door open and turned on the fantastic fan to clear the air.

We have had the propane smell four or five times in our Rv from leaving the stove on .Once we even had the alarm sound so
we are well aware of this issue.I wish it was this simple but the comments and recommendations from hoefler seem to make sense.
I just turned off our front air as the smell is terrible.This has not occured for a while but its hot and happening now.
It is difficult to believe this much smell would be entering through the attic as the entire area near the air box is framed well with
2 by 4.

 

[jtwhites85]

Ok, I have a few questions regarding this subject. We have noticed the same issue with the forward A/C only and I have to get it fixed. First, has anyone found that one or the other fixes (seal the inside OR raise the vent pipes) actually takes care of the problem or is it a case that both MUST be done? Second, as I have never pulled the cap off of the vent cover is it possible to raise and secure the pipe without taking the complete assembly loose from the roof and having to reseal it with Dycor? And lastly, has anyone used the expanding foam insulation to seal the inside of the openings of the A/C to the attic? I keep all three valves closed for the tanks until dumping completely and have checked the two vents on the sinks which appear to be working (shut).

 

[TandT]

Ok, I have a few questions regarding this subject. We have noticed the same issue with the forward A/C only and I have to get it fixed. First, has anyone found that one or the other fixes (seal the inside OR raise the vent pipes) actually takes care of the problem or is it a case that both MUST be done? Second, as I have never pulled the cap off of the vent cover is it possible to raise and secure the pipe without taking the complete assembly loose from the roof and having to reseal it with Dycor? And lastly, has anyone used the expanding foam insulation to seal the inside of the openings of the A/C to the attic? I keep all three valves closed for the tanks until dumping completely and have checked the two vents on the sinks which appear to be working (shut).

I have posted about this at least 2-3 times with my fix.
Look at the threads below the last post here, where it says "similar threads" and you will see a lot of info on this subject. Trace

 

[TXTiger]

Does this condition (sewer smell) happen on factory installed A/C or only after market/dealer install? I am looking into buying a rig in the next few months and am considering ordering one with a second A/C installed in the bedroom by the factory.

 

[jtwhites85]

We purchased the Landmark second hand from a dealer. I have read of this issue in several different threads but have not been able to find the thread that discussed the raising of the vent pipes AND the sealing of the A/C. This is only happening with the forward A/C and it could be prevented by a little extra care during the installation. I can’t tell if the unit came from the factory or was an added option later.

 

[Birchwood]

The factory should seal around the vent pipes on the roof as this is the cause of sewer smell .After
having our front air installed and suffering with sewer smell for months I finally went up and sealed
the pipes with duct seal.The new front A/C was pulling in fumes through the attic from one of our vent pipes.
After sealing the pipes the smell stopped.

 

[wesley1963]

The factory should seal around the vent pipes on the roof as this is the cause of sewer smell .After
having our front air installed and suffering with sewer smell for months I finally went up and sealed
the pipes with duct seal.The new front A/C was pulling in fumes through the attic from one of our vent pipes.
After sealing the pipes the smell stopped.

The factory should also make sure the pipes come through the roof as well. Doesn't seem right to just cut them off below the surface because they didn't line up with the holes in the roof.

 

[hoefler]

Who ever installed your front A/C should have sealed the return area from the attic. The attic needs to be sealed off from the living area completely. Before installing the A/C unit, the installer should have installed sheathing to block off the attic and sealed it with caulk and/or foil sealing tape. By sealing the vent pipes to the roof, the vent will not have any wiggle room as the coach moves around as it goes down the road. If the pipe is solid in the roof, it will restrict the movement in the tank as it expands and contracts with the changes in the water level it will hold as it sloshes around. Sealing the attic off from the A/C unit is the correct way to deal with this situation.

 

[stevebotts]

As odd as this may seem, we poured Clorox down the shower, the bathroom sink and the kitchen sink and the smell went away. Our smell was not continual though. After numerous '"cloroxing" we never had the problem again.

 

[Birchwood]

Who ever installed your front A/C should have sealed the return area from the attic. The attic needs to be sealed off from the living area completely. Before installing the A/C unit, the installer should have installed sheathing to block off the attic and sealed it with caulk and/or foil sealing tape. By sealing the vent pipes to the roof, the vent will not have any wiggle room as the coach moves around as it goes down the road. If the pipe is solid in the roof, it will restrict the movement in the tank as it expands and contracts with the changes in the water level it will hold as it sloshes around. Sealing the attic off from the A/C unit is the correct way to deal with this situation.

I wish not to have sewer smell enter my attic.Even before the A/C was installed there was an infiltration of sewer smell into the coach.The duct seal
remains flexible enough to allow some movement and not allow any shearing of pipes to occur.The forces being applied with the increase of tank
weight should apply to the bottom of the tank not at the top where the vent pipe is attached.I agree with your comment that the top of the vent pipe
should not be rigidly attached to the roof and the A/C should of been installed properly in the first place but we can blame that on Campers World

 

[Jim-n-Leslie]

We had the same issue with our Bighorn. I removed each of the topside vent covers and sealed around each of the vent pipes with flexible expanding foam. That helped a bit, but not entirely. I went on the roof and pulled off the A/C cover. I cleaned up the assembly, removing a wasp nest while at it. That did not do the trick either. I dropped the inside cover, and found that the gap between the inside ceiling and the topside unit was not sealed off, with the insulation exposed. You are correct in that the A/C unit is supposed to draw from the room, move the air through the cooling coils, then blow the cool air back into the room. With the insulation exposed, the unit was drawing air from above and through the insulation. The tanks not being entirely tight with their vents and all, the unit is pulling the fumes through the insulation and into the camper.
I took a role of heavy metallic ducting tape, the kind with an adhesive side and about six or eight inches thick, and sealed off the sides where the insulation was exposed. This ensured the air flow only drew from the room and back into the room. We have not had any foul smell issues since, and the A/C unit works much better.

 

[sundancer87]

Opening the door was the correct action but turning on any electrical appliance with the air charged with LPG is extremely dangerous and sometimes fatal.

The fire department won't shut down a rig on a LPG leak because of the possibilty of creating an ignition source for the gas.

 

[Birchwood]

I may have to check the air box area also as this may be my problem .I have stopped the sewer smell
by sealing the vent pipes at the top but I guess this could lead to other problems like pipe shear at the tank
and inproper venting of the attic .Apparently the gaps around these vent pipes act as vents for the attic.