The Trouble With Tankless Water Heaters

Starting in 2021 Airstream made several big changes in its travel trailers, and one of the biggest was the switch to tankless water heaters.

Tankless water heaters have some great advantages for sure. They're faster to heat water, use less propane, take up less space, require less maintenance, and they're lighter. So there were many good reasons to make the switch.

But the change to tankless has also caused hassles for some owners, judging by the number of comments and questions I've been hearing.

The most common issues seem to be that the hot water is inconsistent (goes from hot to cold "randomly" during use), or that the heater trips off frequently and has to be restarted. 

While writing the 2nd Edition of The (Nearly) Complete Guide To Airstream Maintenance, which you can pre-order through Feb 12 (at a big discount, and with free shipping), I spent quite a lot of time researching and talking with manufacturers to understand tankless water heaters. Here's what you need to know if you have one. 

Many Different Brands of Tankless

Airstream has, in the past couple of years, used at least five different types of "tankless" water heater. These include:

  • Girard GSWH-2 (most aluminum trailers except Classic)
  • Alde Compact (Classic trailers and some Basecamps)
  • Truma Combi (Basecamp 16)
  • Suburban Nautilus (Basecamp 20)
  • Timberline (Interstate 24X and Rangeline motorhomes)

Some are true tankless water heaters, while the Timberline and Truma are hybrid water heater/furnaces, and the Alde Compact has a small tank and heats glycol solution to warm the trailer.

Typical Causes of Problems

Although each of the tankless water heaters work in slightly different ways, they do have a few things in common. For one, they are sensitive. If a tankless water heater doesn't like something, it is usually designed to switch itself off, for safety. This can be caused by things like:

  • low water pressure
  • low water flow
  • inadequate or intermittent 12 volt power
  • low gas pressure (or air in the lines)
  • blocked air intake
  • mineral scale in the heater exchanger
  • clogs anywhere in the plumbing system
  • a leak in the plumbing

A tankless water heater might also under-perform because you're at very high altitude (because burning propane doesn't produce as much heat in thin air). 

Common and Easy Solutions

The number of things tankless water heaters are sensitive to makes troubleshooting a bit tricky, and there is no one-size-fits-all answer. If your heater is working, but you're having trouble getting consistent hot water, start with the basics by double-checking all of the following things:

  • Is the water pressure good (at least 45 psi)? If you have low campground water pressure, try turning on the water pump to boost the pressure. If you have a pressure regulator on the hose, remove it. You don't need it on an Airstream; it's already built-in.
  • Is the hot water flow at least 0.9 gallons per minute? If the faucet is not open fully, open it up. Make sure you don't have anything restricting the flow.
  • Turn down the temperature of the hot water at the control panel, so that you are using more hot water and less cold water. This will keep the heater from cycling off due to the hot water flow being less than 0.9 GPM.
  • Is the air intake of the water heater (outside) clear of snow, ice, wasp nests, spider webs, leaves, etc? Open the exterior door to check, and remove anything that could be interfering with the unit's operation.
  • Are you camping above 3,500 feet? If you are getting weak heat water and are above 3,500 feet elevation and have a Girard GSWH-2, look for the Water Flow Valve (see the Owner's Manual). Try adjusting it clockwise to slow down the water flow and give it more time to get warm as it passes through the heater.

The Cruddy Little Secret

Anything that restricts water flow can be a cause of problems for a tankless heater. But the big secret many Airstreamers are unaware of is that the heat exchangers can become clogged with mineral deposits. If you camp in areas with very hard water, this is something to keep in mind. Even just a millimeter of cruddy mineral build-up in the heat exchanger can cause problems. 

The manufacturers know this. They acknowledge this with an obscure one-line tip buried in their manuals—all of which I read while researching the 2nd edition of the Maintenance guide. For example, in the Suburban installation manual, in fine print on page 6, it says: "Each year, drain the water from the system and flush the heat exchanger with an approved descaling solution."

And that's all it says. Truma and Timberline have similar sentences in their manuals, but none of them tell you anything useful. What's an approved descaling solution? How much do I use, and for how long? How is flushing done?

I've written up a detailed two-page procedure in the new 2nd edition Maintenance Guide that explains everything. If you are having strange problems with your tankless heater (or you'd like to avoid such problems), you should probably check it out. This is something nobody is talking much about yet, but with tankless being the rule for Airstreams, regular descaling (AKA decalcifying) is going to become a very important maintenance procedure for Airstreamers.

Pre-order The (Nearly) Complete Guide to Airstream Maintenance by Feb 12 and Save

Get $7 off the retail price of $29.95, plus free shipping. Books ship beginning in mid-February.

Photo credit: Photo by Tim Wilson on Unsplash

10 comments

Darrall Henderson

Darrall Henderson

Great tips – Please continue to spread the word on workarounds you find. Thanks

Ken Williams

Ken Williams

I had problems with my Girard right from day one in a ‘22 Caravel. I could NEVER get hot water from the kitchen sink without running the lav sink at the same time. I had to run the pump and supplement water flow from the fresh water tank even when I was hooked up to campground water with excellent pressure. I checked all lines, no kinks. Aerators and strainers clear, and no way the coil was clogged up from day one. I’ve sold that trailer and moved to a 2019 with a standard tank hot water heater which is 100x better. You shouldn’t have to do work arounds to get hot water! I know I’m not alone with this situation, as I’ve read about this problem on just about every Airstream forum, with the same workaround solutions.

Anna Brandon

Anna Brandon

Regarding the comment that Airstreams have a built in water pressure regulator—is this only the newer models? We have a 2006 and were under the notion that we needed to always have one…
Thanks!
A

Mikey D

Mikey D

Great article thanks for writing this. As a “hack” one of the things that has worked well for us was to set the water temp on our Girard lower – YES lower. For showers, we first put the shower knob @ full hot. Next we set to a comfortable shower level temperature by adjusting the Girard thermostat. Once set and ready for a shower we just put the shower knob @ full hot. No need to worry about scalding because you already pre-set a temp at the Girard thermostat. The logic behind this is that we’re not mixing cold water at the shower knob to get to an ideal temp.

Da wife likes one setting, I like a little hotter so we have stickers to remind us which temp to set on the Girard prior to showers.

Tankless is not perfect, but I have found some workarounds and compromises that still make it better than tanks.

BTW our rig 2021 GB with Girard tankless WH.

Mike

Lee

Lee

I understand where descaling is an important maintenance process for tankless water heaters. Filtering the water to remove those nasty minerals would help a lot. Do you have any suggestions on water filtering systems to keep the heat exchangers clean in the first place?

Elizabeth Carr

Elizabeth Carr

The other problem is even when they work as designed it’s not ideal for camper. Use in some waves. You’re going to waste freshwater and fill your gray tank waiting for it to heat up. Every time you shut off the water when washing dishes you have to re-wait for it to heat up or are you continuously run water while washing dishes which again feels your gray tank way too quickly. I would argue grating space is far more critical to your average camper van preserving LP. Even when we use freshwater and city water combined, we very often do not have adequate water pressure to make the system kick in for the kitchen faucet. I had great hopes for tankless. But I’m disappointed. Thinking of switching out to a Truma. People seem to love them with almost no complaints. We have a Girard. I’ve done all the troubleshooting. Still unhappy with its performance.

Harrry Preddy

Harrry Preddy

Very interesting article. I look forward to my copy of Rich’s new book arriving.

Our Airstream, Dawn Treader, is a 2022 Globetrotter 27 FBQ. About two months prior to her coming off the line, I requested that they install a “ShowerMiser”. I was told that could not be done by the factory.

After taking delivery last March and spending our first two nights, I realized the hot water system needed improvement (particularly for showers). Waiting for a warm shower wasted fresh water and over taxed the grey tank capacity.

While in a hotel shower, a very simple solution came to me. The tub had a Symmons tub / shower valve with the diverter a lever under the control handle.

I ordered the valve, and with a few plumbing parts was able to divert the “tub” outlet to the water tank and the “shower” to the shower. Simple process. With valve diverter lever to “tub” and water heater powered on, open the

Chris Charbonneau

Chris Charbonneau

I have discovered that our efforts to conserve water are part of the problem. In my International 27 FBT, if I get into the shower (I have set my heat for 115 degrees—so I don’t waste even more water trying to mix hot and cold myself) then pause the water to suds up—then release the water again, it comes back at line temperature, and I have plenty of time to scream while it gets back to hot.

So for my last shower I just sudsed-up quickly while the water ran, and didn’t have the problem.

Richard Jones

Richard Jones

Thanks as always for helping the Airstream community deal with the first world problems we face. We have owned 5 Airstreams (1983, 2008, 2016, 2019 and our current 2022). I am keeping an open mind on the 2022’s tankless hot water heater but so far, it wastes far far more water waiting for it to heat up, and this far far more gray tank space than a tank. Each time you turn on the hot water, it has to heat the water from scratch again. The ShowerMi$er bypass valve helps by returning the wasted water to the cold water tank but so far you have to install these after purchase.

Another item is that using the water pump to improve pressure worked perfectly up until we got our 2022 model. Now, to make that work, there has to be water IN the fresh water tank. I have noticed in North Carolina this summer with full hookups, that when using the pump, the fresh water level kept going lower. It was easy enough to get some water back in the tank, but all 4 of our older Airstreams allowed the pump to add pressure to the system without using fresh tank water.

If you came with full hookups, I think you will like the tankless system. If you dry camp/boondock, it will be less than ideal.

I did some measuring and found a traditional hot water tank that will slide right into the exact opening of our Girard tankless space. We are not doing that yet, but we have one season in with the tankless. We are giving it one more season with the ShowerMi$ers to see if that makes it work.

Happy camping and here’s to first world problems.

Rich Luhr

Rich Luhr

Anna Brandon: Your 2006 Airstream has a built-in pressure regulator. All Airstreams made since the 1970s have been factory-equipped with pressure regulators.

Lee: You can’t filter out dissolved minerals. The only thing that will help will be a water softener. We are currently evaluating softeners and will probably have a recommendation in a few months.

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