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Phil and Ginni Lyons
January 29, 2025
21 views

On Demand Hot Water Heater

Post by: Lifes2short4nofun

I tried a Girard on demand and wasn’t happy with it, so I switched it out with the Suburban 60k BTU on-demand hot water heater and still had the same problem.

It takes a few minutes for the water to get hot and reach the shower. If I pause the shower head for a second to soap up, it has to start all over again and takes a minute to get hot again. I can’t turn on the cold water if I want it a little cooler—I have to adjust the temp on the control panel, otherwise, the hot water goes away. There are some issues with the flow rate through the heater, otherwise, it doesn’t kick in. I have been assured this is how they are. Does anyone else have a different experience with them?

I am thinking of switching to a regular gas/electric 12 or 16-gallon heater. Unless someone has a better suggestion?

Post by: chessie4905

Small electric water heaters are virtually trouble-free. You can spend more on a marine-type that has an engine coolant loop through it. It will supply hot water for 24 hours after parking without being powered, unless you are a heavy water user. Instant water heaters can be nice but add complexity just to save a little space.

Post by: Oonrahnjay

I have a Rinnai on-demand heater at home. I love it—it’s about perfect, except for the $$$$.

Post by: pabusnut

My experience is somewhat similar, except I installed an ultra-low-flow shower head. I don’t shut it off unless I am dry camping, which I haven’t done yet. I have camped with three females who need their showers every day, so I use the campground shower, and they shower in the bus.

I am now down to one female teen with me, but my water consumption will probably be the same until she goes to college. I think the trick is to keep the water flowing, although it may waste a little.

I believe someone on this board devised a way to dump (shunt) the heated water back into the water supply tank to avoid the water heater shutting off, that way only wasting a little bit of propane, and no water. The supply tank temperature would rise slightly, but not much if you only have it off for 30-40 seconds at a time. I probably would have done this too, but I read about it after all my pipes were closed up inside walls. All you would need would be a tee with a gate valve in the pipe between the shower control and the shower head.

Post by: Fred Mc

I’ve had one in the bus for 30 years. For the first few years, we had a lot of problems adjusting the temp until we discovered the problem was caused by the low-flow shower head.

The heater works on water pressure. When you open the tap, the pressure drops, and the propane flows to heat the water. When I turn the tap off, the pressure builds and the propane stops. The low-flow head was causing too much back pressure.

I’m sure on ours if I turned the tap off, the water stops and so does the heating of the water. Turn the tap back on, and the water flows as well as it’s heated. There would probably be a momentary interruption of hot water, but that would be all.

As for the hot water taking a long time to get to the shower head, I would think that would be similar with a boiler-type. There is cold water in the line from the heater to the shower head in both systems.

Post by: eagle19952

20-gallon electric here, in service since 1998. I have found that I can heat the water up and turn it off, and the water stays at least dishwater hot for 24 hours. It’s cheap and easy. There are just the two of us.

Post by: TomC

I have two 10-gallon electric water heaters bought from Home Depot in 1994. One feeds into the next, with the last water heater powered through the inverter for hot water while driving.

When boondocking, the water heats up in about an hour—start the generator when waking up, kick on the water heaters, make coffee, have breakfast, shower, and my wife can dry her hair. Run the generator for 2 hours in the morning and 2 hours at night to keep the batteries up.

I deal with a Christian Camp in Idyllwild, CA. They replaced all the cabin water heaters with instant. That lasted about 2 years—they gave up and reinstalled normal 30-gallon natural gas tank water heaters in each cabin.

Post by: oltrunt

With no room for a real water heater in my little bus, I turned to an Ecotemp L5 on-demand propane system. It works just fine with the following caveats:

  • Use a dedicated high-flow, high-pressure pump.
  • Add a solenoid-controlled recirculation loop.
  • Insulate the hot water lines with foam sleeves.
  • Install a thermostatically controlled burner control—these little heaters can heat the water hot enough to cause plastic pipe failure. The built-in temp setting selector only processes the differential between incoming and outgoing water temps.

Post by: chessie4905

Tom, if you replace the anode rod with an aluminum-zinc alloy, it will eliminate the sulfur smell. Or you can drop the level in each heater and add about 1/2 pint of hydrogen peroxide to each one and then rinse through all faucets.

Good for one or two weeks.
More information here.

Post by: bigred

When my regular water heater went out on me, I let a guy from the gas company talk me into putting one of those tankless water heaters in my house. Absolutely one of the worst mistakes I ever made in my life. Words cannot describe how much I hate this darned thing!!!

Post by: peterbylt

I am seriously considering one of these.

Anyone have any experience with them?

Post by: chessie4905

Bosch also has a 6-gallon version. I’d think the one you’re looking at is a little small. Here’s a 12-gallon with a heat exchanger. A little pricey, but maybe a different brand or dealer will provide a lower price.

Amazon Link

Post by: ol713

Hi, yes, I have one in my coach. They work fine for low use, like a few dishes. They also have a fast recovery, but not fast enough for a shower. Also, you need to be hooked up to a pole. They do take a lot of power. While on the road, the inverter will keep up with it.

Post by: Geoff

I don’t think so. $937+ change? I’m reading that the unit has a heat exchanger—why would you need to run it off your inverter? That is a lot of load for the alternator, leading to a short life. Not to mention the inverter.

I don’t want to brag, but I have an Attwood water heater that has four heat sources: Propane, electric, coolant water loop (from the engine), and radiant heat from the engine compartment.

It has 10 or 11 gallons of hot water in an insulated tank that stays hot all night. A shower control that does not lose hot water when you shut it off to soap up—it's a great system I have been using for 15 years.

I also have a 36-inch angled cultured stone shower with a matching sink and a Fantastic Fan exhaust. I like it better than my huge custom house shower that cost $$$$$. I run my Webasto heater for the bathroom so when I step out of the shower, I don’t get cold.

I told you I don’t like to brag. Can’t help it sometimes.

Post by: chessie4905

I think he was talking about either the 2.5-gallon one or the 6-gallon Bosch unit. Found another one at a better price:

Here are some larger versions:

Post by: Scott & Heather

I have a 40-gallon shorty Rheem electric. It’s supposed to be a 240-volt system, but I removed the wiring, heater rods, and thermostats and replaced them with two 2000-watt 110-volt heater rods and two thermostats.

I have each one wired to a separate breaker in my control panel, so I can turn one or both on and off as needed.

  • Quick recovery? Both 2000-watt elements on full bore = 4000 watts of heating.
  • Just maintaining temp? Flip one off and keep the other one on.

Post by: lvmci

Jack & Fred have hit on my solution that solved my flow issues. The problem was the flow restrictors on the shower head and aerator on the bathroom faucet—they kept the tankless water heater from continually firing.

The kitchen faucet always had hot water continuously, which led me to investigate. I unscrewed the aerator and the shower head, and I finally got continuous hot water!

Before, I had to turn on both faucets just to run hot water. Try my experiment and see if it works for you.

Post by: Lifes2short4nofun

Thanks a lot, I will try that and see how it goes.

Post by: Gordie Allen

I have a 110V on-demand water heater like the one you're looking at on Amazon. I replaced a 10-gallon tank.

We have a dishwasher, washer/dryer combo, and a shower. We’re also full-timers. We really love this unit, and while we can’t run all three at the same time, we can shower and run one of the two others simultaneously.

Plus, we got about 3 cubic feet of additional space—enough to move the cat litter box into the under-washer space.

Post by: dtcerrato

We just love our 20-gallon electric water heater—for decades now. We service it every 7-10 years by cleaning out all the sediment and replacing the anode rod.

Once turned off, it stays plenty warm for a couple of days—and provides more hot water than you can use!

We also have a 6-gallon propane heater for pure boondocking.

Post by: peterbylt

On Amazon, you can select:

  • 2.5-gallon – $169.99
  • 4-gallon – $186.95
  • 7-gallon – $187.53

I would certainly get the 7-gallon. The price difference between these is only about $18—so at $187.53, I consider it quite reasonable.

They are rated at 12A at 120V, which I don’t consider outrageous either.

We currently have a 6-gallon propane-fired hot water heater in our Class C, and we never run out while taking a shower. But to be fair, the shower in a Class C is so ridiculously small, you don’t stay in there long anyway.

Post by: chessie4905

I’d compare the recovery rate between propane and electric. That may be important.

Post by: Oonrahnjay

Exactly. It runs on 120V or propane, except that I very rarely need to run it on those because the heat from the engine warms it.

Compact unit, lots of hot water—and it has a built-in tempering valve to take 180-degree water from the engine coil and mix it with cool water.

The 11 gallons in the tank becomes 20-25-30 gallons delivered to your taps!

Post by: bigred

When my regular water heater went out on me, I let a guy from the gas company talk me into putting in one of those tankless water heaters in my house.

Absolutely one of the worst mistakes I ever made in my life.

Words cannot describe how much I hate this darned thing!!!

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Article written by Phil and Ginni Lyons

Phil Lyons has been a Bus Nut and moderator of the BCM forum for many years. He and his wife Ginni live in the central highlands of Arizona.  Phil’s day job is in IT Security and Ginni is a retired Registered Nurse.

They are the proud parents and grandparents of daughters, granddaughters, and two spoiled dogs.

Phil and Ginni are part of a bluegrass/gospel trio called Copper Mountain StringAlong, are members of Bethel Baptist Church in Prescott Valley, and volunteer and serve in various capacities in the church and the community.

RVing has been part of their lives for over 35 years, and they both hope to enjoy the bus lifestyle for many more years.

You can contact Phil via email at

Phil@BusConversionMagazine.com

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