Foul urine odor when running the furnace

[Lenartshorty]

In the process of checking all the systems in our newly acquired 2018 230 RL, we found when running the furnace it filled the entire trailer with a terrible smell of urine. We spent the day yesterday determining that the odor is behind the bulkhead underneath. We checked behind the furnace and everywhere that we can see so far with a flashlight because an RV tech advised us to look for an animal nest. Like mice. We can’t find any sign of that so far. We are beginning to wonder if the odor is coming from below the basement in the frame, perhaps the black or gray tank? We don’t know if there have been leaks in the past. Considering drilling a small hole in the low point of the coroplast, which appears well sealed, to see if any liquid comes out. The trailer was in storage for the last year and a half. Also wondering if mice could make a nest inside the heat ducts? Any thoughts?

[TucsonJim]

In the process of checking all the systems in our newly acquired 2018 230 RL, we found when running the furnace it filled the entire trailer with a terrible smell of urine. We spent the day yesterday determining that the odor is behind the bulkhead underneath. We checked behind the furnace and everywhere that we can see so far with a flashlight because an RV tech advised us to look for an animal nest. Like mice. We can’t find any sign of that so far. We are beginning to wonder if the odor is coming from below the basement in the frame, perhaps the black or gray tank? We don’t know if there have been leaks in the past. Considering drilling a small hole in the low point of the coroplast, which appears well sealed, to see if any liquid comes out. The trailer was in storage for the last year and a half. Also wondering if mice could make a nest inside the heat ducts? Any thoughts?

Rodents are notorious for getting into places you'd never expect. Regarding the coroplast. Before cutting or drilling a hole, I'd suggest you try removing a series of screws along the edge and peering into the underbelly with a flashlight to see if there are any signs of items that need to be addressed.

In order for the urine smell to get into the furnace, it's probably being picked up in the return air side. I pulled the drawings on your 230RL to locate the return air path. According to my latest drawing, the return vent is located under the stove. I'd focus on the area between the stove and the furnace.

Jim

[howson]

In the process of checking all the systems in our newly acquired 2018 230 RL, we found when running the furnace it filled the entire trailer with a terrible smell of urine. We spent the day yesterday determining that the odor is behind the bulkhead underneath. We checked behind the furnace and everywhere that we can see so far with a flashlight because an RV tech advised us to look for an animal nest. Like mice. We can’t find any sign of that so far. We are beginning to wonder if the odor is coming from below the basement in the frame, perhaps the black or gray tank? We don’t know if there have been leaks in the past. Considering drilling a small hole in the low point of the coroplast, which appears well sealed, to see if any liquid comes out. The trailer was in storage for the last year and a half. Also wondering if mice could make a nest inside the heat ducts? Any thoughts?

Another place you might want to check is the "squirrel cage" area for any evidence of a critter. Pull off the exterior cover and peak inside.

[Lenartshorty]

Another place you might want to check is the "squirrel cage" area for any evidence of a critter. Pull off the exterior cover and peak inside.

Had the outside cover of the furnace off yesterday looking with a flashlight up the tubes and no sign.

[Lenartshorty]

Rodents are notorious for getting into places you'd never expect. Regarding the coroplast. Before cutting or drilling a hole, I'd suggest you try removing a series of screws along the edge and peering into the underbelly with a flashlight to see if there are any signs of items that need to be addressed.

In order for the urine smell to get into the furnace, it's probably being picked up in the return air side. I pulled the drawings on your 230RL to locate the return air path. According to my latest drawing, the return vent is located under the stove. I'd focus on the area between the stove and the furnace.

Jim

My husband is considering removing a few screws in the coroplast to look; we will reserve that as last ditch to look for any old puddled escaped sewage. We are going to do a couple flush and fills of the tanks before that point since it’s been empty so long. I am happy that we have a little time before winter because there is no odor in the coach unless we run the furnace, at this point.
I had the drawer under the stove opened yesterday and did see a small piece of the furnace ducting that runs through under there all the way to our door, underneath the TV cabinet. As near as I can tell there is an air return or floor grate to the basement behind the toilet in the bathroom, but there is no attached ducting there.

[flyfshrockies]

Lenartshorty Perhaps that furry nose in your avatar could help locate the problem. My money is on a rodent leaving it's calling card and a pile of nesting material in or near a duct for the furnace.

Good Luck

Dave

[TucsonJim]

I had the drawer under the stove opened yesterday and did see a small piece of the furnace ducting that runs through under there all the way to our door, underneath the TV cabinet. As near as I can tell there is an air return or floor grate to the basement behind the toilet in the bathroom, but there is no attached ducting there.

Julie - I went back to the prints and took a look at some photos and it sure looks like the return air path is actually under the bottom drawer under the sink. I'm attaching a photo below to show the entrance to the return path. But designs change all the time, so I wouldn't be surprised if it was routed behind the toilet at one time or another.

[Lenartshorty]

Lenartshorty Perhaps that furry nose in your avatar could help locate the problem. My money is on a rodent leaving it's calling card and a pile of nesting material in or near a duct for the furnace.

Good Luck

Dave

Well, if this had been the Lottery, your money is good! The furball in my avatar is worthless for sniffing out mice however we realized the duct going into the bathroom was slightly pulled away underneath and when we had run the furnace no warm air at all was coming out. My husband crawled in there and took apart that piece of duct work and even before he was done I could see there was a rust hole in the bottom of it. Sure enough it’s plugged full of a mouse nest. We completely disattached that one and are going to try to run the furnace, blocking that exit, and see if we still have odor. Really hoping we don’t have to pull any more of these apart. It is tight space in there and I am all impressed that my 73-year-old DH could wiggle in there far enough to get this done.

[Lenartshorty]

Julie - I went back to the prints and took a look at some photos and it sure looks like the return air path is actually under the bottom drawer under the sink. I'm attaching a photo below to show the entrance to the return path. But designs change all the time, so I wouldn't be surprised if it was routed behind the toilet at one time or another.

Checking that now, Thankyou!

[flyfshrockies]

Lenartshorty Glad you found the blockage. Next is finding the entrance area for the critters. It is amazing what tiny holes they can use, look in the unlikely spots, I have seen the dernd things jump 3 feet to try and get into a motor home we had. You might want to borrow the neighbors cat as an advisor for your pup.

Dave

[Lenartshorty]

[TucsonJim]

Well that seals the deal. They certainly changed that one.

Jim

[Country Campers]

Julie

The first photo is the cold air return behind the toilet , not sure why it is placed there. Cover that when using the AC , uncover when using the furnace. Covering helps keep the cold air from filling the pass thru storage. Looking down into that register you can see into the pass thru storage , this will be behind the rearward wall that is removable, lots of fun things to find behind that wall.

Brian

[Lenartshorty]

Julie

The first photo is the cold air return behind the toilet , not sure why it is placed there. Cover that when using the AC , uncover when using the furnace. Covering helps keep the cold air from filling the pass thru storage. Looking down into that register you can see into the pass thru storage , this will be behind the rearward wall that is removable, lots of fun things to find behind that wall.

Brian

Thanks, we are thinking it is the cold air return also but were thrown because we were assuming the cold air return would have to be ducted right to the furnace, like in our home.
Hubbie saw the rearward wall, that looked impossible almost to access; hope there is never a need. 🤪

[Lenartshorty]

Lenartshorty Glad you found the blockage. Next is finding the entrance area for the critters. It is amazing what tiny holes they can use, look in the unlikely spots, I have seen the dernd things jump 3 feet to try and get into a motor home we had. You might want to borrow the neighbors cat as an advisor for your pup.

Dave

😳 Bought traps today and will be looking in the near future for holes to plug. We live in Northern MI so the only outdoor cats I know of around here are not domesticated…