Just installed the high tech little beast, all went well. Mounted the box outside of the house, caged in a nice insulated wooden box, which is vented bottom and top. Connected up to a brand new fresh propane tank. Bought a regulator rated for 140Kbtu, then piped up to the unit with black flexible rubber line that came with the regulator. Maybe this is not the proper diameter? My tank is only about ten feet away, but the iron pipe routing would be rough. Considering soft copper, nut not sure about the fittings. Is soft copper gas line a different thing than water line? Are you supposed to use a flare tool and flare fittings? I was told once that natural gas is now corrosive to copper, but is propane still good to go?

Also my vent stack is a double wall 5 inch type B, just like they asked for, only mine is just 2 feet tall, not the requested 6 feet. Wind interference is not likely an issue as the rain cap fits nicely under the eave, about 14 inches down from touching anything. Winds above the roofline are severe at this lakefront location, but the unit is mounted in a fairly nice pocket of safe air on the leeward side of the house.

The incoming water supply is pretty cold right now as well, not sure of the exact temp but it is enough to make you not want to wash your hands. I set the adjustment knobs for maximum flame/minimum flow, even though the max adjustment turns to the left and the min turns right. The manual says to use min flow for highest possible water temps, but the drawback is that when you choke down the flow too far it takes forever to pull hot water to the tap. My nearest outlet is the kitchen sink and it will fill half of a five gallon bucket before it starts to feel warm. That seems like a lot. The sink faucet could be too small to trigger the heater, but the shower is definitely not and it does the same thing.

Hacking into my steel roof and poking a vent stack up into the wind is my last resort, though I have considered it. Maybe size up the gas pipe, maybe a different regulator. I have a dual gauge welding regulator that fits the propane tank, not sure about that for a permanent fixture but it may help figure something out, just don't want to accidentally blow out the seals on the factory fitted regulator(inside water heater).

Propane is new to me, natural gas is not. Any thoughts?

Well here is the answer to my own question!
We finally got it all worked out, and the problem was basically that the appliance was asking for a larger volume of propane than my rig could supply. I was able to get ignition with my welding regulator, though it would not sustain the cyclic action of the on demand use without locking up. It seems if you put too much pressure up against the factory regulator, a seal engages and the thing says no thank you- too much too fast. Very sensitive. So I went to the propane shop and picked up a bigger reg. rated for 250Kbtu. I did end up running 1/2 inch iron pipe from the unit for about five feet, then 3/4 stainless flex to the new regulator. If you give these heaters enough gas, they really are impressive machines. We got down on some numbers with a thermometer and found a very nice rise- something like 50 to 120F in a matter of seconds. Stunning! Just try to think about boiling a pot of water on the stove, how long does that take? Oh my, and just one pot... now shift the gears up to get infinite pots, and turn the speed up to mach 10. Watch out Marie!
So time will tell on gas usage. Right now I have a 12 gallon bottle hooked up. I choose this size because I can actually lift it when full without snapping anything in my back. Hopefully I won't be taking it in for refills too often.
Also a tip about the heater, pay no attention to the indicator on the flow control knob. It suggests that min flow is found clockwise at about 2 o'clock, but if you keep cranking on it you will get a much bigger range of motion. This is not in the manual.
As for the people crying on Amazon about Lowe's not having all the parts- suck it up. Almost every Lowe's in the country is located with a mile radius of a home depot, and within a lager radius usually a wal-mart. The possibilities for combining parts from these three places, at a fair cost no less, is simply mind blowing. Throw in a tractor supply and the results grow exponentially. God bless America.

Curbside, thanks for the info. May be of help to someone else. I'm glad your pleased with the water heater, I'll go that route when my tank needs replaced. Would you care to say the overall costs? Thanks again.