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Old 06-20-2015, 09:43 AM   #1
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2013 Interstate Coach
Fort Worth , Texas
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Tankless Hot Water Heater

Has anyone installed one of the new tankless hot water heaters on their AI and if so, what has your experience been. It seems to me going tankless would eliminate several problems as well as providing a continuous supply of hot water when needed.

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Old 06-20-2015, 09:55 AM   #2
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I've done some research online and here. I bought one because it's just me usually and I plan to camp mostly w full hookups. Be certain to keep water pressure at recommended on all faucets. I got lucky and got a new one on eBay for $250 so price wasn't an issue. Tons of opinions out there. If you use full hookups mostly its great. Also can b easier winterizing. Size isn't much different. I found reviews online very enlightening.

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Old 10-07-2017, 07:04 AM   #3
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I'm resurrecting this thread because this is our next focus of research.

In the two years +/- since the last reply here, has anyone added a tankless water heater to their Interstate?

My initial impression is that all Interstates, including the newer ones, have a conventional 6 gallon water heater. In a 2017 thread by OP Notstock, the comment was made "Looking at the specs for some other interstates, both EXT and regular lounge, they all list it as being a 6 gallon tank and looking at the logo on the corner of the door in photos it's an Atwood."

We want to convert to tankless because heating 6 gallons at a time is an absurd scenario in a rig that is used mostly for boondocking. It's wasteful of water and it's wasteful of propane. That kind of hot water heater is great if someone is hooked up and doesn't face water limitations. But it's just too wasteful off-grid. And I'm tired of boiling one individual pot of water on the stove at a time, every time I wish to wash dishes or wash my face. It's time for an upgrade.

Product recommendations? Anyone? Anyone? Bueller?
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Old 10-07-2017, 09:03 AM   #4
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Tankless water heraters are rated for gallons per minute. The smallest propane-fueled one carried by Home Depot is a 2gpm model by Marey, which should be more than adequate for your needs. It's also propane-only, and uses D-cell batteries for flame ignition, no electric wiring needed.

Here is a link to the installation manual for this model:
And the owner's manual:
WBCCI #1105

My Google-Fu is strong today.
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Old 10-07-2017, 09:14 AM   #5
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Page 7 of that manual states that the unit needs only 8 psi water to fire, which is promising. My research is in its infancy, but some of the RV-targeted models seem to state closer to 20 psi. I don't know if we have that. Running now on lithium batteries, our pump produces better pressure than it did on the old AGM, but I don't yet know what the number is.
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Old 10-07-2017, 09:57 AM   #6
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Installing one of those would be a tankless task!
John W. Irwin
2014.5 Touring Coach, "Sabre-Dog IV"
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Old 10-07-2017, 09:57 AM   #7
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What is not mentioned on the tankless heaters is water quality required to keep them from being throw-away after a couple of years, and ease to winterize and/or how they keep unit from freezing up if circumstance staggers heat source or ignition...

For example, the upper Midwest is blessed with alkaline limestone infused groundwater, city tap water here was at/above 8.4pH and 400ppm carbonates for decades - none of the units I researched could deal with those levels. Yes, of course, its a migrating unit and may not see sour water for months at a time but it is something to consider when wondering why tankless is not an automatic OEM installation.

And to weather & frost proofing I have a friend who built a micro-trailer and lived in it over two Wisconsin winters, he was all excited about the heart of his heating system being the energy efficient tankless heater - then he woke up to flooded everything including his bedding from odd drafts defeating the simplified electronic ignition and the tiny frost proofing resistance heater. There are units that will simply stop heating program and drain the system on cold temperatures but keeping the unit(s) protected in a mobile application takes some extra design...

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Old 10-07-2017, 10:36 AM   #8
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I have a precisiontemp RV550, though not in an AI. My only gripe with the system is that it takes a good bit of water flow through the unit to activate it. That makes taking a navy shower a little more involved, since you have to adjust the valves to get enough water flowing through the hot side every time you turn the water back on, then quickly readjust to get the proper temperature. Only takes a second, but you have to do it every time or you'll get cold water. The heater seems to stay on at much lower flow rates than it takes to get it going. This is likely to be an issue regardless of the brand or design of the tankless heater you get.

That said, I still love our tankless heater and would definitely get it again.

FWIW, we soften all the water we put in our trailer to protect our appliances and allow us to use less soap and water for washing. It's worthwhile to do that regardless of the water heater design.
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Old 10-07-2017, 10:43 AM   #9
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Originally Posted by Pahaska View Post
Installing one of those would be a tankless task!

- - Mike
2013 Airstream Interstate Lounge EXT
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Old 10-07-2017, 03:06 PM   #10
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An interesting spread in functionality and especially cost in these models. The one Protag cited retails for about $100. The RV 550 lists for $1,125 on the manufacturer's website. There are numerous other models in between. I have a feeling that there's a spreadsheet in my future for listing specs, installation constraints, pros, cons, and costs.

We've owned our Interstate for 3 years, and during that time in our location, we've had exactly the same number of freezing days as Mexico has had days in which fish fell from the sky. We always pray for at least a couple of short weeks of bearable autumn weather before deer season commences (because deer season severely restricts camping opportunities), but this year we may not get it. It's 90 degrees outside as I type this, so winterizing is even further from my mind than it usually is. We have never winterized our rig - haven't even come close to the need. We may never winterize. But water heater drainage ability is a concern, albeit a far lesser one for us.
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Old 10-07-2017, 03:26 PM   #11
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I just do not agree that the 6 gallon tank heater is "wasteful". I have had a tankless heater. Much prefer the tank model.

It does not waste water because you only use what you need and the rest stays in the tank. Not so much with the tankless heater. We only turn the WH on for about 15 mins either once or twice a day. It is pretty well insulated and it stays warm enough for washing hands all day or night long. We use a tank of propane in about a month with WH, propane stove, and maybe a little heat. Have the electric heater option but prefer to run it on propane because it gets too hot when plugged in all the time.

My idea of wasteful would be to take out a working 6 gal WH and doing all the plumbing or wiring to put in a tankless heater.
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Old 10-07-2017, 03:55 PM   #12
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Originally Posted by InterBlog View Post

Product recommendations? Anyone? Anyone? Bueller?

You may want to research the 2018 Interstate and see what make and model they are using. Knowing them, they selected it for ease of install so it may offer some insights into options.
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Old 10-07-2017, 04:04 PM   #13
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My experience with the existing heater is that it runs propane for closer to 30 minutes until it's ready, which is why I never use it for small tasks such as washing dishes. For that, I just boil water on the stove, which is much faster.

The last time I used the existing water heater was in December 2015 when I was on a job, staying at a campground, and had 3-way hook-ups at my site. With 3-way hook-ups, it's a no-brainer - sure, go ahead and use it - those are the operating conditions for which it was designed. But that's literally the last instance in which I had 3-way hook-ups.
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Old 10-07-2017, 06:58 PM   #14
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The tank on my 2006 takes maybe 10 minutes at most to have a fair amount of hot water. I rarely run it more than 15 minutes at a time.

Perhaps checking the burner/insulation or something on yours?


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