Replacing Furnace Flex Pipe, couple questions?

[Firefighter1406]

Okay am the very normal victim of a mouse getting in the under belly and making a next in the flex pipe, also chewing multiple “doors” down the length. So I pulled the under belly plastic down on that side to take a look.

Kinda crazy on all the crap they leave in the under belly. I have pieces of pecan, fittings, electric wires, you name it.

1. Crazy thing is they used a 25’ piece of flex pipe to go about 8 feet. Which brings the question is that excess for the “heated” under belly with the Polar Package, or just the quick RV trailer factory way?

2. The factory flex pipe had quite a few holes in it. Not sure if that’s from the mouse or from it rubbing on the under belly going down the road. I am thinking about replacing all the furnace pipes in the under belly with hard pipe, to try and midi-gate any more mouse hotels in the furnace pipes at least. Is there any issues with doing that? Also, should I use solid wall pipe or get the aluminum flex pipe that is still flexible it’s just more rigid?

3. If I need to stick with the flex pipe is there anything special I need to consider with purchasing new?

Thank you for reading this post and appreciate any experience you can pass along with me. This is my first camper that has ducted furnace so just want to make sure I don’t screw it up.

[chuckster57]

Sorry to hear about the unwanted tenants. I would stay with flex hose mainly because it’s going to be much easier to route. If you go rigid, think of how many turns your going to have to buy, not worth it IMO. I don’t see a need for 25’ of hose for an 8’ run. If it was meant for “4 seasons” heating, maybe 10 or 12 feet will do the same thing.

[Firefighter1406]

Well I didn’t know I had asked such a brain buster :P

I did get this done though. I ended up dropping the cloplast or whatever it’s called plastic garage sale sign material down on that side of the camper. I found quite a few extra pieces of wire and plumbing pipe left from the build. Keep some of that for spares. Found the chewed though flex pipe and was going to just patch it but the inlet where it went though the floor was close to where I was at. So I just replaced from the vent all the way to the furnace. It was a tight fit getting it through the floor but in the end it all worked out. Popped off the furnace cover and found a few small items from the unwanted guest in there, thankfully nothing major. Took an 8’ piece of flex pipe to fix. I will be keeping a new section in the camper for a spare and a couple more 4” hose clamps just to be safe. I saw the 2” flex had some holes as well. Need to google and see where I can get that from next.

[JRTJH]

One source is Amazon: https://www.amazon.com/AP-Products-013-665-Flex-Duct/dp/B00KQPCE8A/ref=sr_1_9?dchild=1&keywords=2%22+flex+hose&qid=1598195105&sr=8-9 Unfortunately, they only sell it in 25' lengths. At least that's the shortest I've found on Amazon.

Many heating/supply stores will have it on hand "by the foot". Many high volume air delivery systems are going to 2" ducting to fit in smaller interior spaces, so it's usually pretty easy to find locally.