I can tell you what I did. My iPh is right on my pad, inches from my heater. Unlike some of the other acid tank solutions mentioned on this forum, that utilize whatever acid-holding containers users come up with, the iPh sports a lid that is very similar to the one you find on a pool pump's debris basket: quarter turn to remove/replace, with an o-ring to seal it tight. The only other exit for fumes is a small connector, onto which you connect the vent tube (hose) you're referring to. I have a vinyl fence right next to my pad, so my vent tube runs under the fence and vents on the other side. That set up has been in place for over a year, and so far there is some evidence of corrosion, but it's hard to say if some of that corrosion was already there, or would have occurred without the iPh present, or happened when I spilled acid a few times while filling the tank (I'm better at it now, but spillage has occurred).
I've attached some images I took just now, you can judge for yourself. The rust on the gas pipe was there before I owned an iPh (I don't think it has progressed significantly), which leads me to believe that this particular location is somewhat prone to corrosion with or without an iPh. The corrosion on the iPh itself, its hold-down screws and that conduit might be from fumes, or it might be from spillage. The corrosion on the filter band and furnace bolts may or may not have already been there, or have occurred without the iPh. The hinge, which is only about a foot away from the exit of the vent tube, isn't really showing any corrosion at all, and the gas meter, also about a foot away, isn't either.
Nothing really conclusive about this report, other than if corrosion is happening from the iPh exposure, it's not really all that bad. Now that I have this photo chronicle, I'll revisit this in a year and submit findings at that point.
I didn't really have an alternate location for the iPh. It could have been a foot or so away, but that's about it. If the corrosion
is from the iPh, I would deem this acceptable for the convenience it provides. If it's eating away at the internal components of my pool heater, I can't really test for that, and since I never use the thing, and don't ever plan to (it was installed by the previous owner and has been replaced with solar heating), it's kind of a non issue (except for maybe the next owner).
I would say do what I'm doing, put it in the most convenient spot, run the vent tube as far away as possible, and take some pictures. Then set up a reminder to check it periodically (once or twice a year?) and compare photos. Though I wouldn't end the vent tube anywhere near your galvie fence. I don't see why that tube would have a length limit. It's just air inside it. Extend it as far away from metal as is practical. If after some time, you notice more corrosion than you're comfortable with, deal with it then.
Keep us posted.
