Propane plumbing Q.

[Almot]

Will be installing catalytic space heater. Have to run ~ 8ft length of 3/8 OD copper tubing from the black Tee below/outside through the floor to inside, and then to the heater.

Route that I like:
1ft from Tee to the floor hole -> inside through the hole -> 1.5ft along the floor, hidden under dinette bench, through the valve -> 6ft along the wall to the heater, this is on top of wheel well under the table. Total run 8.5ft, probably less, considering valves etc. Unsupported length from valve to heater = 6ft, BUT I intend to support it (see below).

Q: Is 8.5ft total too long? Usually, 3/8 tubing is for short 4-5ft runs. But, my 8.5ft length it's mostly inside (only 1ft is outside), and trailer is on seasonal site, rarely moved. Also, I intend to support 6ft run along the wall with 3/8" straps like these ,
and cover it with some molding. It's not getting in the way, because it goes along the wall on top of the wheel well. Oddly, there aren't many 3/8" straps - mostly 1/2" or larger.

Another route - I don't like it:
3ft from Tee, UNDER the frame cross-beam, to the floor hole -> 2ft along the floor, hidden under dinette bench -> 1.5ft along the wall to the heater. Total run 6.5ft, unsupported run 3.5ft.

The manufacturer DID run 6ft length of 3/8 tubing to water heater exactly this way, UNDER the I-beam, covering tubing with split-loom and then with a bottom plastic sheet. Though they did it aft of the wheels, so if I hit anything, the axle will be hit first and then - 3/8 tubing. My heater tube would be fore of the axle, so the 3/8 tube would take the first hit. I doubt that split loom and plastic sheet is a good protection. But then again, my rig is not moved often.

Sorry for long post 😉

[Almot]

Thanks, Westend. I already thought of checking cable clamps etc in electrical isle. No, my yet to be received 5500 BTU heater doesn't require a bigger pipe, manufacturer says it has 3/8" flare connector.

[westend]

I would use method #1 and protect the 1' of exposed copper under the floor with a piece of abandoned water hose. 3/8" copper will be fine for this appliance and the amount of pipe involved. Unless the mfg. strictly calls for a larger dimension of pipe, you should be fine.

FWIW, I have about the same length of the same size tubing for my stove (maybe more). It works perfectly.

If you are close to a big-box store, check the electrical section for different clamps. Sometimes, there are more choices in electrical than plumbing. The ones you depicted, though, should work out well.