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, 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.
Order The (Nearly) Complete Guide to Airstream Maintenance from Airstream Life magazine.