VEVOR 12L Propane Hot Water Heater 3.2GPM 24KW Tankless Instant Boiler Stainless Steel Liquefied Petroleum Gas Water Heater with Shower Head Kit...

Converting An RV To A Tankless Water Heater – Part 1

The Old Heater

This 2001 travel trailer had an Atwood 6 gallon propane / 110V water heater installed. On a good day it was a 5 minute shower–maximum. Being over 15 years old when I got this RV, the heater didn’t have many good days. When I finally pulled it out, it leaked from the tank itself and had a constant leak in the pressure release valve. I spent a couple years trying to keep this thing and all the plumbing around it alive, but it was all too far gone. Both shutoff valves leaked, as well as the bypass valve. The factory design had the water lines coming straight up through the floor, with all three valves floating in the air!

In addition to the water heater AND the plumbing completely failing, there was extensive water damage to the sub-floor of that entire side of the bedroom. The original heater was embedded inside the built-in nightstand, with a screw-on access panel. So on several ocassions there were weeks-long leaks where I didn’t see it buried in the nightstand.

The old Atwood water heater gave up the ghost!
The old Atwood water heater gave up the ghost!

It was obvious that the nightstand would have to come out to repair the sub-floor if I wanted to do it right. Even a drop in replacement that I could bolt right up was going to be a lot of carpentry and plumbing. The idea of a tankless water heater sounded appealing, but I originally discounted it since people were saying how much work it was to convert from a tank to a tankless setup. But the more I thought about it, the more it made sense to put in the extra work since it was already going to be a major project.

Electric Tankless

The electric ones were pretty easy to rule out. Even the tiny 6 kilowatt heaters would overload the 30 amp service on my travel trailer. Electric is out, at least for tankless.

Eemax EEM24006 Electric Tankless Water Heater, 6KW, Blue
Eemax EEM24006 Electric Tankless Water Heater, 6KW, Blue

Drop-In Propane

The tankless drop-in replacements sounded interesting at first. Bolt it up in place of the old one and you’re done. No worrying about venting because it vents where the old one vented. This one costs $1,200 and gets 3.9 stars on Amazon–less than inspiring. but it has 55,000 BTU. Doesn’t sound terrible, but digging deeper into the specs, it’s only 1 GPM! That’s in the same ballpark as my old tank heater, but for $1,200 it seems … underwhelming. So, even if I was willing to spend that much, there’s just no way…

PrecisionTemp RV-550 Tankless Water Heater - Wall Vented
PrecisionTemp RV-550 Tankless Water Heater – Wall Vented

If you’re willing to spend a measly $500, you could get this one with 42,000 BTUs. I couldn’t find the GPM rating but I’d expect it to have a flow rate in line with the one above-ish. Didn’t seem like much of an upgrade, if any. This one only gets a rating of 3.7 stars. I didn’t really read the reviews, but I figured most people would be underwhelmed by a water heater that’s probably under-powered BTU-wise.

Girard 2GWHAM On-Demand Tankless Water Heater
Girard 2GWHAM On-Demand Tankless Water Heater

As I widened my search to any tankless propane water heater, it soon became obvious that I was looking for an upright model. Lower cost, much more BTUs, but much harder to install into the existing space of an Atwood.

Name Brand Upright Tankless

This is where I spent most of my research. There are lots and lots of these upright models, and many of the name brand ones like this Excel and others which offer a decent price and good install experience. Pay in the $200-$300 dollar range, and you’re not gonna have to worry about weird fittings or instruction manuals in Chinese. You’ll get nice, standard NPT fittings, so everything you buy at Home Depot will fit splendidly.

TANKLESS GAS WATER HEATER (LOW PRESSURE STARTUP) 1.6 GPM LPG VENTFREE (PROPANE)
TANKLESS GAS WATER HEATER (LOW PRESSURE STARTUP) 1.6 GPM LPG VENTFREE (PROPANE)

But, you’re still getting a Chinese water heater. 90% of all tankless propane models seem to use almost the exact same design, with the only variations being on display and fittings. The generic ones mostly get bad reviews, even where they look identical to the name brand ones with good reviews. Identical D battery setup with many of the same reported problems. They are also much, much cheaper than their name brand counterparts. I was intrigued by this and started digging into hundreds of reviews of the generic heaters, before finally deciding on one.

Generic Upright Tankless

There seemed to be a couple general themes in the reviews of the generic Chinese models, like “fittings leak” and “impossible to seal” and “threads are all wrong.” Surely they couldn’t all be flawed? Not to mention “temperature is in Celsius” and “water/gas inlets labeled in Chinese.” But it also seemed that some people were solving these problems. Sure, it’d be nice to have the readout in Fahrenheit, but honestly, I just want hot water.

VEVOR 12L Propane Hot Water Heater 3.2GPM 24KW Tankless Instant Boiler Stainless Steel Liquefied Petroleum Gas Water Heater with Shower Head Kit...
VEVOR 12L Propane Hot Water Heater 3.2GPM 24KW Tankless Instant Boiler Stainless Steel Liquefied Petroleum Gas Water Heater with Shower Head Kit…

It turns out that these generic heaters all come with 1/2″ BSP metric fittings, also called “G” fittings, instead of the 1/2″ NPT fittings you’d expect in the USA. I’m sure if you are in the UK, then all the fittings from your local hardware store will work fine. But here in the USA, those water inlets on your generic water heater are going to leak when you hook NPT fittings up to them.

Someone in one of the reviews linked this adapter fitting, and the little light bulb went on in my brain, and I did the quick math. Because people are generally completely desperate when they realize they need these rare fittings, they are really over-priced. But even paying $25 for two fittings, the cheap generic heaters still looked appealing. Very appealing, in fact.

Choosing A Model

After doing much research, and talking to my brother the plumber, I decided the 3.2 GPM models were about the biggest I could fit in the space, and probably a little more than I needed. I decided on this one, which I actually found for 90$ shipped on eBay!

VEVOR 12L Propane Hot Water Heater 3.2GPM 24KW Tankless Instant Boiler Stainless Steel Liquefied Petroleum Gas Water Heater with Shower Head Kit...
VEVOR 12L Propane Hot Water Heater 3.2GPM 24KW Tankless Instant Boiler Stainless Steel Liquefied Petroleum Gas Water Heater with Shower Head Kit…

At about $90 plus the $25 in special fittings, I was getting a 24kW heater, which I did the conversion and it came out to about 82,000 BTUs! My brother pointed out that I would need a larger diameter gas hose than the old one.

Armed with the knowledge of what I needed, I proceeded to order everything. It turns out that the cold water inlet is much shorter than the hot, so it needed a rubber washer inside the adapter fitting on the cold inlet. Lucky for me, the heater came with the rubber washer for the gas inlet adapter that I didn’t need, and it worked like a charm inside the fitting! But that’s part 2…

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