On-demand water heaters – do they work?

[rogerddd]

We have a new Thor brand class C motorhome with an tankless Girard Brand RV water heater. In the shower the water will temporarily turn warm after the hot water faucet is on and run for a while, but it cycles between warm and cold, so we end up showering with mostly cold water. Both the manufacturer and RV repair facility tell us the same thing: run the faucet until warm water flows, then reduce the flow to sustain the warm temperature. When hooked up to city water, this almost works but with dry camping it does not work well and takes too much water to sustain even water occasionally warm. Washing dishes offers a similar experience. Anyone have good success with tankless water heater in their motorhome? Is so, how did you get it work?

[RSD559]

One of the YouTube RV folks, don't remember which one, tackled this problem. The solution was to turn down the temperature at the water heater to about what you want in your shower, which makes sense, but isn't obvious. That way you only turn on the hot water, and that keeps the water heater from cycling on and off. If you want warmer water for doing dishes, turn it up to what temp you want, then turn it back down when you are done. I believe it was The Fit RV. He's very good at looking for solutions for RV problems.

[montgomery19d]

montgomery19d wrote:

The Atwood "extreme cold" package can be found ***Link Removed***.
The installation manual for the kit is ***Link Removed***.

The links...
The Atwood "extreme cold" package can be found ***Link Removed***.
The installation manual for the kit is ***Link Removed***.

[montgomery19d]

We just installed the Girard tankless, the newest gen. We are having issues with the copper inlet pipe freezing at night. None of the actual pipes freeze, and it runs its anti-freeze feature without issue, it's just freezing in the 3-ish inches of pipe from the inlet to the heating element.

Does anyone have any suggestions for preventing this?

We're considering turning the gas to the water heater off at night and just running the "hot" water tap in the bathroom to keep water moving. This concerns me though because then it can't run its freeze-prevention cycle to ensure the heating element is fully protected.

We've tried leaving the unit on and running the "hot" water at a flow low enough to not turn the unit on, but it continually throws error codes.

I've found that Atwood offers an "extreme cold" setup for their unit. Any opinions on whether or not this could be used on the Girard unit? I'm mostly just looking at the insulation aspect of the kit to wrap the inlet tube, and hopefully prevent it freezing there. The Girard and Atwood units seem similar in general overall design.
The Atwood "extreme cold" package can be found ***Link Removed***.
The installation manual for the kit is ***Link Removed***.

My husband currently lives in the camper for work, so normal winterization procedures aren't an option at this point in time.

Aside from that, we aren't having any major function issues, despite the very cold water temps we have here. There is slight fluctuation in temperature when it is running, but it is not extreme or unbearable. We think it work's pretty well overall.

[Wild_Card]

westend wrote:

Wild Card wrote:
Tankless on deman require a certain flow to work. Not good for rv in my opinion

What if the hot output of the on-demand heater was somewhat looped/bypassed back into the fresh water tank? That would keep the flow rate up and water wouldn't go into a waste tank/sewage hose. A valve in the heater loop close to the water tank could be the only control needed.

The logistics of plumbing like this may be beyond easy installation, in some cases. In my rig, it would be easy, I have the freshwater supply pipes inside an interior chase leading to the back.

BTW, what is the sound level of these tankless units?

Could be done, but would need an automated 3 way valve and a control scheme.

[pconroy328]

westend wrote:


BTW, what is the sound level of these tankless units?

Less than the furnace.
Maybe 3/4ths the wooosh of the furnace.

[pconroy328]

If you pop over to the Jayco forum you'll find out a ton of information on living with the Girards. we've got a Gen II Girard in ours and have learned some of it's quirks.

They are very sensitive to changes in flow. So adequate pressure is a must. For those campgrounds without enough flow, I just fill the fresh water tank and then pump from that to shower.

You might have a Gen III Girard, and it's a bit different, but essentially you want to shower with only the hot water spigot on. You adjust the temp so that it's comfortable coming out of the one, hot, tap. Trying to mix in cold water to cool it down usually doesn't work.

Nope, they're not good for boondocking. But we're a family of five and when on full hookups, a tankless water heater is pretty nice!

[westend]

Wild Card wrote:
Tankless on deman require a certain flow to work. Not good for rv in my opinion

What if the hot output of the on-demand heater was somewhat looped/bypassed back into the fresh water tank? That would keep the flow rate up and water wouldn't go into a waste tank/sewage hose. A valve in the heater loop close to the water tank could be the only control needed.

The logistics of plumbing like this may be beyond easy installation, in some cases. In my rig, it would be easy, I have the freshwater supply pipes inside an interior chase leading to the back.

BTW, what is the sound level of these tankless units?

[Passin_Thru]

Nope!

[Wild_Card]

Tankless on deman require a certain flow to work. Not good for rv in my opinion

[ScottG]

On paper, the new Atwood tankless WH looks very promising. It has the highest BTU rating and it has two stages of heating power so it works great at both lower and higher flow rates. This technology addresses the biggest complaints users have about other brands, ie min flow. It seems to get some very good reviews and a few (confusing) bad ones too. It's also the most expensive.
If I were in the market for a tankless, I would research it further.

[bobndot]

Do a search on the Truma tankless water heater.

Yes, people have been saying that the Girard is not the best for boondocking because it has to run in order to sustain hot water, filling up your holding tank as well running you dry.

[Lwiddis]

Not as well as a real water heater and not for boondocking IMO.

[kerrlakeRoo]

Cycling off and on is common on tankless systems.
These units need a minimum flow to turn the heater on, if the flow drops the heat turns off. Mixing hot and cold reduces the Hot flow just enough to shut the unit down.
Try barely opening the hot water at the bathroom sink while running the shower. Just a small steady stream will often give the unit sufficient flow.