Possible Cold weather issue with Furron Tankless Water Heater

[RBK21]

My wife and I are new to the RV world. We own a 20220 Grand Design 31mb.
At present time we have parked it at family farmland and are staying in it when we visit my wife’s sisters who all live next to the farm. We have 50-amp service connected to a farm pole for shore power. We are using the clean out of the septic tank to dump black tank. And using a “well” for the source of city water.
I am concerned about a problem which could surface when we plan to stay at the 5 th. wheel in December. We plan to stay there the 2nd week of December and Christmas week. The RV is parked in central NC. If ambient temp remains above freezing, I have no concern. But there is a chance that there could be brief period when the temp will go below 32 degrees. (could be just over night or could be longer). The real cold weather does not hit this area to Jan and Feb.

My initial thoughts is that when we are in the RV using the furnace to keep the RV comfortable then a brief period of below freezing will not affect the water system. The RV is equipped with a Furrion Tankless Water heater. While looking at the Grand design owners forum I came across a thread titled

Furrion Tankless Water Heater - Important: Please Read 04-26-2021, 11:26 AM

" Just a heads up for anyone with a Furrion tankless water heater. They have no cold weather protection and according to the Furrion manual, they need to be winterized when the outside temperature is expected to be below 39°F. Failure to winterize may cause the heat exchanger to rupture if it freezes. This can cause very expensive repairs and water damage to the RV."
Reading further in the thread I saw this post:
" The screen shot of your text didn't make it thru, so I'm trying to read between the lines on what was said, It appears that your dealer told you the propane heat system would be enough to keep the tankless heater from freezing, and the GD person agreed? the post right after yours seems to say the exact opposite. Is there anyway you can just type out the message that you are trying to screenshot?
Thanks, this tankless heater freezing is an issue as we frequently go camping at 20 degree over nite temps"
Also there was a post that contained an email form someone at Grand Design:

rom: Daniel Carr <[email protected]>
Date: October 14, 2021 at 1:24:56 PM MDT
Subject: RE: 2021 Grand Design Reflection 337RLS and Furrion Tankless Water Heater - M9913452
Good afternoon!
My apologies for the delay in getting back to you. I only received the notification today.
But I do want to thank you for reaching out to us with your question. We appreciate hearing from our customers.
Yes, the tankless water heater is not designed for temperatures that can reach below 39 degrees. However, the trailer really isn't a "four season" as most customers feel that phrase means. Can it be used in coder temperatures? Yes. Can it be used in temps that get to 32 degrees and below? To a certain extent, yes. Whenever you get in temperatures that reach 32 degrees or below, you run the risk of freeze damage - whether or not the trailer is said to have four season ability. Water freezes at 32 degrees and there is no escaping that. The risk that something may freeze is pertinent even in Class As, Class Cs or any RV. It's nothing that can be escaped or changed. Freeze damage isn't covered by warranty so every precaution must be taken.
For example, if you look on the sidewall of the trailer, you will find a vent for the back of the refrigerator and one for the water heater. These are open to the outside air and there is no way to insulate them from the outside temperatures. Those are exposed to the heat and cold 100% of the time. I wouldn't want to take the chance of damaging either because I'd be the one who had to pay for the replacement(s).
On the flip side of the "four season" statement is the extreme heat. Customers who travel to California, Arizona, Utah, Texas, New Mexico, Florida, etc. can see temperatures exceed well over 100 degrees. The A/C won't be able to keep up with the high heat (especially if the air is humid as well). Can you operate the trailer in excessive heat? Yes. Are you taking a risk being in the heat? Also yes.
There's more to both sides of the coin but I think you get the idea as to what I'm conveying.
I'm happy to discuss the issue further if you'd like or answer any other questions you may have.
Have a great day!
Daniel Carr
Retail Service Manager
Grand Design RV
It seems to me there is at the very least 2 different opinions on this issue.
My question is:

1. Can we safely camp during December at the location I described above?
2. Being a novice camper, I do not want to be unduly concerned about an issue therefore, I am asking the advice of more experienced campers as to how to consider this issue.
3. What do you guys do if you want to stay in RV during a period where the temp may fluctuate between above freezing during day and below freezing at time? Do any of you have a rv with the Furron tankless water heater and how do you camp in the winter. We really want to be able to use the camper to stay there during December.

We plan to winterize when we leave after Christmas week but my concern is being able to stay in the camper using water etc.
Thanks for any advice we can get
RBK21

 

[Kirk]

I have never had a tankless water heater so can't comment on the degree of problem but I have a lot of experience RVing in weather well below freezing. Water doesn't instantly freeze at 32°F, that is the point at which the process begins but the water must reach 32° and that takes several hours. There is no problem with even an exposed fresh water hose freezing until the temperatures go below 30° and stay so for several hours. I was never concerned until the lowest temperatures went to 28° or lower and stayed that way for several hours. Since your Furron has a cover that hides the heat exchanger, it would not be exposed to wind or to direct outside air contact which should make it take at least some longer to freeze than would an exposed water hose.

 

[SuwanneeDave]

I think it would help if you ran the hot water right before going to bed and first thing in the morning. Also if you need to get up during the night run it then also.

 

[Lou Schneider]

I had an Atwood tankless water heater that the previous owner installed in my Sunnybrook trailer. An unexpected 30 degree low was enough to destroy it. The heat exchanger is a bunch of copper tubing in the flame chimney so it's directly exposed to the outside air. Without much water volume in the heat exchanger, there's little thermal mass to delay the freeze up.

Reading the manual after the fact, it was supposed to keep the flame on at a low setting below 39 degrees to prevent it from freezing. Since the rig was in storage with the propane turned off this didn't happen.

 

[DonTom]

There is no problem with even an exposed fresh water hose freezing until the temperatures go below 30° and stay so for several hours.

Since I have been RVing, that has happened to me only one time. In January in Las Vegas! I wonder what the temp was and for how many hours . . .

-Don- Reno, NV

 

[DonTom]

Can we safely camp during December at the location I described above?

More than likely will be fine, as long as your DC is on. I know in my new RV, a DC heater for the water for the tankless comes on at +40F/ +4.44C.

But if you have the manuals for your RV, that is what I would go by.

Besides the fact if the RV is warm enough for you inside, anything freezing outside that is mounted, or in, should not happen.

-Don- Reno, NV

 

[Utclmjmpr]

You have power,, so can you place a small cube heater in the same area as the water heater and any other sensitive areas??..>>>Dan

 

[Lou Schneider]

Besides the fact if the RV is warm enough for you inside, anything freezing outside that is mounted, or in, should not happen.

-Don- Reno, NV

What is being overlooked is the heat exchanger for the Furion (and the Atwood I had) are directly exposed to the outside air because they're in the flame chimney. The chimney is well insulated from the interior to keep the heat contained within it during normal operation which also prevents the interior air from warming it when it's cold. It's directly exposed to outside air which fuels the flame and vents exhaust gasses. Without the thermal mass of a large tank of water the heat exchanger will quickly track the outside temperature.

Of course, a tankless heater that's mounted entirely inside the living area will be protected as long as the interior air is heated.

 

[DonTom]

What is being overlooked is the heat exchanger for the Furion (and the Atwood I had) are directly exposed to the outside air because they're in the flame chimney.

What year was that rig? I assume it was one of the first where they used tankless.

-Don- Donner Summit, CA

 

[Lou Schneider]

What year was that rig? I assume it was one of the first where they used tankless.

-Don- Donner Summit, CA

It's a 2003 but the water heater was an aftermarket replacement by the previous owner, installed in the same location as the previous tank heater. I replaced it with a 6 gallon Atwood and it dropped right in.

 

[DonTom]

It's a 2003 but the water heater was an aftermarket replacement by the previous owner, installed in the same location as the previous tank heater. I replaced it with a 6 gallon Atwood and it dropped right in.

That probably explains why it froze, wasn't designed for a tankless.

-Don- Auburn, CA

 

[Lou Schneider]

How would you design the space differently? Furion looks like it fits in a standard water heater cutout.

 

[DonTom]

How would you design the space differently? Furion looks like it fits in a standard water heater cutout.

I would think wherever and however they can keep it warmer, but I would leave that to the experts.

I just assume there is a reason why 30F destroyed yours and mine is still fine after being exposed to 27F for several hours.

I checked it when I got back to Reno after my Oregon trip. All was fine.

-Don- Auburn, CA

 

[RBK21]

thanks for this discussion I plan to contact the service department where we purchased the camper and see what they say about this issue. Luckly the area we will be using the rv should not get below freezing weather until late November.
what is the worse case result if we are camping in the 5 th wheel, and temp drops unexpectedly below freezing enough to cause freezing issues; are we talking about having to replace the tank-less water heater or is it something worse? trying to determine our risk

 

[DonTom]

what is the worse case result if we are camping in the 5 th wheel, and temp drops unexpectedly below freezing enough to cause freezing issues; are we talking about having to replace the tank-less water heater or is it something worse? trying to determine our risk

If you're living in it with the furnace on, it isn't much of an issue.

If everything is off, ice can cause pipes to crack or burst open and other such issues, as the water expands to ice.

Normal water heaters can prevent ice by just being on. The problem with the tankless is that there is no warm water except when actually being used with the water running.

-Don- Auburn, CA

 

[N.C.WAnder]

what is the worse case result if we are camping in the 5 th wheel, and temp drops unexpectedly below freezing enough to cause freezing issues; are we talking about having to replace the tank-less water heater or is it something worse? trying to determine our risk

Heads up, I'm new here. I was looking for tips on repairing the tankless water heater in my 2022 GD 31MB... when I came across this post.

I live in WA State. The west side of the state is moderate and rarely freezes. The east side (where I live) is more high-desert and snows and freezes all winter. I bought the trailer on the west side, then pulled it home. I Assumed that it was at least blown out, if not fully winterized when I took possession. I should've asked!!!!

We plan on using our 31MB in the winter a lot for ski trips. On the maiden voyage, I park the trailer, set it up, then turn the water pump on and it just stayed on. After some investigation, water was pouring out of the water heater bay. That was three weeks ago. I was able to isolate the water heater and continue to use water from the fresh tank.

So, here are some options that I'm considering going forward:
1. Unscrew the felt backing next to the wet-bay and point a small box heater at the heat exchanger
2. Only use hot water for showers. When I'm done, blow out and drain the water heater, then close the valve again. Labor intensive!
3. Don't use hot water in sub-freezing temps. Just bypass the water heater all together and boil water for sponge baths.

This might not help much since December is come and gone. In the future though, you should be able to bypass the water heater altogether... there's no configuration for it in your paperwork, but on my P01 panel, I just turn the red handle on the bottom left and it cuts off the water heater.

Otherwise, I'd love to hear how others have handled this situation. This is the first year that I've tried winter camping. From what I understand, GD Reflection has gone exclusively to the tankless heaters. Sounds like there's some debate about whether or not it's any good.

 

[John From Detroit]

If you get a cold snap. Try draining it. unlike tank heaters they do not (Generally)( self protect. a small space heater. depending on how cold a 100 watt incandescent lamp in a cage inside the compartment with it.... Might protect it.

 

[Gary RV_Wizard]

If the incoming water is extremely cold, a tankless heater may not be able to adequately heat it. It only raises the water temperature by some pre-defined amount, e.g. 50 or 60 degrees. That might still be a cool shower.

If the tubing that feeds water to the heater hasn't frozen, why do you think the heater itself would freeze? After all, it is self-heating. And if the water line tubing has frozen, you aren't getting hot water anyway. Or any water.

 

[Lou Schneider]

If the incoming water is extremely cold, a tankless heater may not be able to adequately heat it. It only raises the water temperature by some pre-defined amount, e.g. 50 or 60 degrees. That might still be a cool shower.

If the tubing that feeds water to the heater hasn't frozen, why do you think the heater itself would freeze? After all, it is self-heating. And if the water line tubing has frozen, you aren't getting hot water anyway. Or any water.

The tubing feeding the water heater is usually in an enclosed space, maybe even heated when the furnace is in operation. The Achilles' heel of a tankless water heater is the heat exchanger coil inside the flame chimney. The chimney is directly exposed to the outside air so the flame can vent and is also insulated from the inside warmth.

Grand Design said in the first post the water heater "has no cold weather protection". At least the Atwood in my rig (which also froze and split open) was supposed to turn the flame on low when the temperature dropped below freezing. Apparently the one GD chose doesn't do this.

 

[Gary RV_Wizard]

Good point, Lou. The exchanger would always have water in it, heated or not, so vulnerable to freezing if the water isn't being heated.