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2022 Transit 350 HR Cargo AWD w all windows, AC and Coolant taps,
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Discussion Starter · #1 · (Edited)
What's best practice for floor feedthrus and especially how to seal against bugs and air drafts? I feel like I'm winging it. See photo with two 1-1/2 inch ABS for grey drain and grey tank vent and an electrical feedthru for small cables for tank heaters, tank level sensors, Espar fuel pump. The electrical one is the standard conduit to box plastic fitting which does have a nice smooth interior, an extra one is sitting to the right. I guess I plan on using expanding foam to finish the job. Is there a source for larger dia grommets bigger than the 2 inch I found on Amazon? I'm hole saw drilling, sanding rough edges, painting with a polyurethane POR paint based on someone's suggestion somewhere and using his 2 screw holes to get a small amount of paint out at time and my suggestion a long wood stick cotton swab for a "paintbrush'. Hood Automotive tire Trunk Bumper Automotive exterior
 

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2019 T-350 HR 148 Extended 3.5 EB, Full time 2 person build, Chinese Heater, Victron, 525 AH Lithium
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I used these for the floor for large pipes and plumbing ICON 12483 Holding Tank Fitting - 1-1/2" Rubber Grommet, Black https://a.co/8i8vBjD look at this fitting type. I prefer it to what you are showing above and it comes in multiple sizes.
 

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Possibly a boat through-hull could work (tho I like the rubber grommet idea above).

Just a side note on any PEX sticking out the bottom of the van. I don't know if this is a common/known thing, but when I bought my current RV it had been stored in a warehouse. I could see that no mice or rodents had been inside the unit (whew), BUT every place where a few inches of PEX stuck out underneath (tank drains, etc.) it had been gnawed off by rodents. Not sure what the answer is. Maybe not have any hanging down; maybe covering it with something....?

(Okay, decided to Google just to see and at least bobvila.com says that rodents find PEX irresistable so it wasn't just a fluke.)
 

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I used Carlon PVC Male and Female Terminal Adapters. They are standard electrical conduit fittings that are available at Home Depot, Lowes, and ACE Hardware. They come is a wide range of sizes.


 

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I used large grommets to protect wires that go through the floor of my Transit. Lowe's has a good selection in the drawers in the hardware department. After the wires were in place, silicon caulk sealant was applied at both sides of the grommet for waterproofing. Be sure to first apply a little paint to any holes drilled through the van sheet metal to prevent rust.
 

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2022 Transit 350 HR Cargo AWD w all windows, AC and Coolant taps,
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Discussion Starter · #8 ·
I used Carlon PVC Male and Female Terminal Adapters. They are standard electrical conduit fittings that are available at Home Depot, Lowes, and ACE Hardware. They come is a wide range of sizes.


Good suggestion, thanks. And if I don't want the extra height, I can just band saw off the threaded part so it is shorter that the male treaded part sticking thru the floor and so use the factory smooth edge. I really didn't like the looks of the metal threaded ring, pretty now, rusty later.
 

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2022 Transit 350 HR Cargo AWD w all windows, AC and Coolant taps,
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Discussion Starter · #9 ·
What most people use on the roof of their Transit would probably work well in the floor too.

thanks for the reply. I've used the water tight connections for flexible conduit to a box as in on the outside of your house but not used these. Sometimes just knowing the right names for items is the key step.
 

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2022 Transit 350 HR Cargo AWD w all windows, AC and Coolant taps,
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Discussion Starter · #10 ·
Possibly a boat through-hull could work (tho I like the rubber grommet idea above).

Just a side note on any PEX sticking out the bottom of the van. I don't know if this is a common/known thing, but when I bought my current RV it had been stored in a warehouse. I could see that no mice or rodents had been inside the unit (whew), BUT every place where a few inches of PEX stuck out underneath (tank drains, etc.) it had been gnawed off by rodents. Not sure what the answer is. Maybe not have any hanging down; maybe covering it with something....?

(Okay, decided to Google just to see and at least bobvila.com says that rodents find PEX irresistable so it wasn't just a fluke.)
When you replaced the Pex, what did you do to protect it? The snap on plastic corrugated looking loom? Some tape with glue that they also like the taste of? A new concern. I guess thanks for the heads up.
 

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When you replaced the Pex, what did you do to protect it? The snap on plastic corrugated looking loom? Some tape with glue that they also like the taste of? A new concern. I guess thanks for the heads up.
I actually didn't replace it, because I changed the systems instead. (Two sections were low point drains drain from inside through the floor, but I can just pump the system out plus I put in an access port for cleaning/getting the last bit out of the tank. The other section was part of a black tank flushing system but there are other ways that are better now, IMO, because that type of system had a tiny nozzle inside the tank that would get clogged anyway.)

But what would I do now.....I guess I'd think about transitioning to copper maybe at that point? I would definitely protect it somehow because in this case the rodents did absolutely nothing (thank goodness) except gnaw off every bit of PEX that was exposed under the chassis (they were clearly never inside and all that PEX was fine).
 

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Discussion Starter · #12 ·
But copper not too good with an accidental freeze. How about the rubber couplings for DWV pipe? How do they fare with rodents, any idea? I used 3 so my double gate valve grey and black drain assembly with some elbows and such all come out as one unit simply by loosening the 3 rubber couplings. My two underneath Pex A Lines will go straight out of an undermount fresh water tank and with a gentle curve go up into the van. Plenty of room to add lot's of layers of loom/tape/rodent food.
 

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2021 Cargo T350 EL High roof AWD Ecoboost
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For my drain lines I am using PVC bulkhead from here: Bulkhead Fittings & Tank Adapters | PVC Bulkhead Fittings | FlexPVC®.com
Website looks outdated but they carry a large assortment of stuff and ship quickly. Have ordered multiple times from them and no issues. They also reply to their email and answer questions.

Some photos of my shower drain solution:
Wood Material property Gas Wood stain Hardwood

Automotive tire Camera lens Wood Automotive exterior Automotive design


I can't find another picture but into this I can thread a 1" NPT to 1" Barb fitting, and the same underneath the van. Going all the way through all layers of the floor, it creates a water-tight seal so if anything leaks it stays on the floor (the final floor layer is a vinyl sheet, not yet installed when this photo was taken - I have since removed the bulkhead and put on the vinyl floor and the bulkhead will go back in once I get to that part of the build)
 

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But copper not too good with an accidental freeze.
Yes, agreed if they will have water in them. In my case they were straight "cut off" pipes out the bottom of my rig (drains) so no way for them to hold water. When they weren't in use (99% of the time) they were closed off by a valve inside on the floor. Then when you wanted to drain the system you would open the valve and the water would go straight down and out, but would still not have any way to sit in the pipe since it was vertical and just open at the bottom. All of the pipes inside are still PEX and I would not change them (rodents better not chew those!)

Still, the copper was just a quick thought. May not be best (and especially not if your use case has water sitting in loops or something).
 
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