Furrion tankless water heater freezing

[DMScheer]

I have been searching but don't see this addressed on this forum. I have seen a vid on a problem with the Furrion tankless water heater (Model FWH09A-AM) freezing even though it has been winterized. The explanation is that there is a mixing bowl in the rear of the unit that doesn't have a low point drain. I have found one post on another forum that asks about it but not much response at this point. According to the vid the replacement part is not available and they are no longer making that model of the water heater. The vid is on YouTube by paradise in a tin can, it is a good video and he shows what happened and what they did to fix it. What he showed makes a lot of sense and I am surprised that i can't find more information on the topic.
I have blown out my system with air and was hoping not to have to put antifreeze into the system. I have some thoughts to open up the bay to access the back of the unit and remove the bowl just to see if there is water in it. I don't know if this was an isolated incident of poor winterization or a common problem.
Thanks

[ncitro]

DMScheer It is definitely recommended to winterize with antifreeze, and in the case of the tankless do not bypass the water heater. One of our moderators has in the past blown out his unit with air and checked his lines to find water still remaining in the low points of the lines as the air "flows over the water". The Furrion tankless should have antifreeze run through it, and both drains (there are two) pulled until antifreeze is visible draining through it. There have been several discussions (the forums search is not great), and most stemmed from only blowing it out, or winterizing with it bypassed (a hold over from the tank water heaters that you did not want to fill with 6 or 12 gallons of antifreeze).

[Jlawles2]

DMScheer There is a red knob on the back of the unit (its mentioned in the manual). When blowing out the unit, this knob needs to be turned a few times to help purge the water from the mixing chamber (it's documented in a thread here somewhere). Even in the manual it states to exercise the valve manually several times a year to ensure the line is clear.

NOTE: the red knob is a wedged (?) ramp system and as you twist it, it will open the valve then slam shut as you cross the top of the wedge.

I think the valve is an overpressure or over temperature device. I cannot tell as I could only barely see it on the back of the unit in my 303 through the access door in the hutch.

Excuse the poor screen shot from Amazon, but you can see the red knob here (orientation may be different as mine is).:

[DMScheer]

Thank you for the insight. I will put some antifreeze into the system. The internet is good for information, unfortunately it can be to much at times. You don't always know what is genuine.
I will look for access to the relief valve.
I have lost confidence in some of the manuals that came with the camper. I have 3 different "instructions" for the leveling system and they have different information. Also my control panel does not do some things that the manual says it should do. But that's another story. 😂

[DaveH]

I realized this week after viewing a video about winterizing a tankless water heater that the Nautilus P1 plumbing panel was designed with a conventional water heater in mind. The type where you don't want to fill a tank with antifreeze.

The only P1 settings where fluid flows through the water heater are city water and dry camping.

I found instructions for winterizing my tankless water heater in my Grand Design manual and in a free LCI training video (Session 3 - How to Operate and Care for Your Furrion Tankless Water Heater) at time stamp 4:14.

My sequence is to blow out the trailer including the water heater, push anti-freeze through the trailer using the trailer water pump (instructions in the Nautilus manual) and then use a plunger type hand pump to push anti-freeze through the water heater. With the fixtures closed and the lines full of anti-freeze the hand pumped anti-freeze has no where to go but out through the water heater.


https://lippert.thinkific.com

Lippert Technical Institute (online)

Free Course Name: Owners Guide to the Furrion Tankless Water Heater

[cauldlad]

I realize this is an older thread, but it has a title that may/should come up in searches for this issue (Furrion tankless water heater freezing).

I have a 2022 Reflection 150, 260RD with a Furrion tankless water heater, and the heater began to leak badly after de-wintering the unit last spring.
Fortunately, my unit was still under warranty and Grand Design agreed to replace the leaking heater with a new one.

But while researching the cause of leaks, I (as others), came across a lot of information with regard to causes and preventions with regard to Furrion tankless water heaters.

I'm convinced it's a design issue related to the "vortex mixing bowl" Furrion uses to prevent temperature fluctuations.
The mixing bowl is very difficult to drain and retains water when compressed air is used to clear the system, and even when anti-freeze is added to the system the water in the bowl isn't displaced.

There's a very informative YouTube video on this issue that explains the problem very clearly and offers a fix (although it's not for the feint-hearted!): https://www.youtube.com/watch?v=-ivfmwM64ZU

The leaking heater in my unit is currently being replaced, but I was still concerned about how to stop the heater freezing in the future, since we travel between seasons.
A little more research revealed that Furrion has made an effort to address this problem:

a new module board called Control Unit With Freeze Detector that is designed as an antifreeze option that is $103. Part Number 2022006595. It turns the unit on automatically if the temperature goes below 38 degrees and heats the water to keep it from freezing. It will then shut off at 58 degrees. (see https://www.rvtravel.com/how-do-i-ke...ing-rvdt-2088/)

I only just checked with my dealer to find out if the replacement model being installed in my unit has the "control unit with freeze detector," and indeed it does, so good news for me!

But for those who have Furrion on demand water heaters without this new "freeze detector module," the good news is that the module is available for sale and may be a better option than many of the convoluted "fixes" that have been proposed.

[DaveH]

Thanks for the post I watched the video it helps to know what the design flaw is

[BR549]

It sounds like Furrion’s replacement part is best for full timing but maybe not so good for winter storage.

I winterized my trailer for the first time after watching the video about the problem with the mixing bowl. Not sure if I had blown all of the water out of the bowl, I placed a 60W incandescent bulb in the space near the water heater and left it on all winter. The light kept the space near the water heater warm even on the coldest nights. (Granted, this is north Texas and not northern Minnesota, but we still get sub freezing temperatures occasionally.). With the light plugged into shore power at the storage yard, I was able to remove the batteries from the trailer and store them in my garage for the winter.

Of course, someday I will run out of incandescent bulbs and then I will need a different solution.

[Jlawles2]

It sounds like Furrion’s replacement part is best for full timing but maybe not so good for winter storage.

I winterized my trailer for the first time after watching the video about the problem with the mixing bowl. Not sure if I had blown all of the water out of the bowl, I placed a 60W incandescent bulb in the space near the water heater and left it on all winter. The light kept the space near the water heater warm even on the coldest nights. (Granted, this is north Texas and not northern Minnesota, but we still get sub freezing temperatures occasionally.). With the light plugged into shore power at the storage yard, I was able to remove the batteries from the trailer and store them in my garage for the winter.

Of course, someday I will run out of incandescent bulbs and then I will need a different solution.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 they make them in various wattages.

[gtippett]

Hey Everyone, please note the unit does drain if properly winterized. Please see this video https://www.youtube.com/watch?v=hf3Z0j9rBJs. The video posted above, he is wrong, the mixing chamber does drain. Also note that Grand Design did send a number of units out in 2021 that didn't follow the proper winterization proceed as Furrion didn't tell them (or knew). So that is most likely why the unit in the video uploaded above failed.

The only safe way to winterize this unit (especially in Northern States or Canada) is to ensure when you winterize that you winterize with the hot water unit NOT in by-pass.

[TedS]

I wonder, if then, GD could eliminate the water heater bypass in future tankless water heater builds because it no longer serves any function.

[Jlawles2]

Note if you open the magic red valve on the back of the unit it will drain the mixing chamber. I have done this with air pressure (luckily we live in the south so winters are almost non existent).

If I were to use antifreeze, I'd still cycle the valve to eliminate as much water as possible in the chamber and lines before performing the antifreeze installation.

[ncitro]

I wonder, if then, GD could eliminate the water heater bypass in future tankless water heater builds because it no longer serves any function.

They're doing this for exactly the reason you state.

[gtippett]

Jlawles2, that "magic red valve" you are talking about is the pressure reducing valve (PRV). In normal operation, that valve's mechanism should be dry (water should be only present on the pressurized side). If the valve is opened, or pressure is too high, or it has failed, water will be on both sides. It is just another form of the PRV that is on the traditional tank systems. But instead of a lever, it is a twist release. This "magic red valve" should not be mistaken as the water heater bypass, which GD is now placing at the new location, behind the P1 panel. They are still providing the bypass to permit maintenance on the tankless.

To drain the tankless unit, open the drain plug on the unit (small brass fitting), open the faucets and let it drain. Majority of the water will come out, you can hear the chamber drain if you listen to it. Now due the configuration of the tankless (like any tankless) it has a number of bends, which will prevent all the water from leaving. So I think it is a must to put anti-freeze in it.

[Cate&Rob]

Furrion requires that the "magic red valve" (the pressure relief valve) be cycled as part of regular maintenance. So . . . owners need to have a plan for accessing the back of their Furrion tankless water heater to accomplish this. See attached screenshot from the Furrion manual.

Rob