Corrosion of Alde Convectors

ScottG · April 2021

Curiosity question here...

In 2016 or 2017, nuCamp added hinged lids and storage cubbies to the bunk headboard. Can somebody with one of these newer models describe how this impacts access to the convectors located below?

(My 2015 has only a simple shelf across the headboard. Once you lift it off, the expansion tank and rear convectors are reasonably accessible.)

db_cooper · April 2021

At least I've found all the glycol hoses have a little extra length, so I can take some pressure off the fittings. That was not the case with the propane line to the fridge recall we had. That sucker was tight.

Bayliss · April 2021

@ScottG, I have never removed that storage area, but the below discussion threads are the best ones that depict it. I do not recall any photos for the 2016 or 2017 models, but it does not seem that the storage cubbies have drastically changed in design since nuCamp started adding it.

This discussion thread shows the removal of those storage compartments from a 2018 320 S:

https://tab-rv.vanillacommunity.com/discussion/11631/wireless-rear-view-camera-on-a-320-s#latest

This one shows the area in a 2020 320 S:

https://tab-rv.vanillacommunity.com/discussion/13070/permanent-side-to-side-sleeping-for-t-b-320-s/p1

glesieutre · April 2021

I have a 2015 S-Max. We have rarely used the Alde system for heat (and probably electric then), and never for hot water. As a result, I have not worried about changing out the working fluid (40-50% ethylene glycol). I've been thinking about it though, and came across this thread. Now I'm more worried. I just took this photo of the rear convector connections on the reservoir side. To me, the slight bulge does not appear unusual. Am I mistaken? When I get a chance, I'm surely going to change out the fluid, but it's likely to be couple of months.

Denny16 · April 2021

It does not make a difference whether you run the Alde or not, the glycol just sitting in the system has a limited effective shelf life (2-years is the recommended life), as it is in contact with the aluminum bits in the Alde system. This is enough to allow or cause corrosion after the anti-corrosion additives loose their effectiveness. This is why Alde and nüCamp recommends changing the fluid every two years.
cheers

fstop32 · April 2021

@glesieutre, I'd say the good thing is that bulge looks very minor compared to the ones I had, but you don't want to ignore them. I'd suggest checking those out when you change the fluid.

ScottG · April 2021

@glesieutre, while yours are comparatively small, those are the telltale bulges several owners of older T@Bs have reported. I'd bet more than nickel you have some corrosive deposits forming under those hoses.

While heavy use of the Alde does seem to be a factor in accelerating the problem, lack of use is not necessarily preventative. It's also not clear that changing the glycol on schedule would have prevented the buildup, either.

The only consistent variable in our small (but unfortunately growing) sample seems to be age. Reports of bulges thus far have been from 2014 and 2015 T@Bs. I hoping as more owners start getting their trailers out of winter storage we'll get more reports (good or bad) that will give us a better handle on the extent of the issue.

ScottG · April 2021

@Bayless, thanks for the links. I guess I had missed the relevant photos showing that the cubbies were one removeable unit. Makes sense. It adds an extra step to accessing the rear convectors, but not a particularly onerous one.

Those cubbies are larger than I thought. While I'm not completely sold on their usefulness, it looks like retrofitting something similar in older T@Bs wouldn't be a terribly difficult project.

ChanW · April 2021

That Loctite sealant Alde sells says in its docs, 'to remove, soak in alcohol.....' Seems that would make it pretty useless against glycol!

I wonder if anodizing the ends would have been a preventative. Or maybe high-temp silicone grease?

I also agree, those clip type clamps don't seem to be as dependable as a screw type. But the screw type doesn't seem to fit the circumference as well as the clip type does. I wonder if the screw type would press the rubber against the aluminum as well, all the way around, as the clip does.

ChanW · April 2021

Didn't we learn that the boiler innards are stainless steel, so less likely to have this problem?

db_cooper said:

............
I'm thinking that the boiler is probably compromised to some extent, so switching to the new fluid is not worth the trouble.

Longer term, I may replace the entire system, as long as it's cheaper than a new trailer, and of course use the new fluid.

ScottG · April 2021

ChanW said:

...
I also agree, those clip type clamps don't seem to be as dependable as a screw type. But the screw type doesn't seem to fit the circumference as well as the clip type does. I wonder if the screw type would press the rubber against the aluminum as well, all the way around, as the clip does.

Having removed and replaced several of them, I feel those clip-type clamps deserve more credit than they get. They are pretty tight and they are designed to apply even pressure all the way around the fitting. I have the same impression as @ChanW regarding the limitation of the screw clamps, though I suspect either work just fine.

ChanW said:

Didn't we learn that the boiler innards are stainless steel, so less likely to have this problem?
...

This is not entirely the case. See my post of April 7th at the top of page 3.

UPDATE: I've sent an inquiry to service@alde.us inquiring as the composition of the wall between the glycol and the domestic HW. I'll report back when (and if) I hear anything from them.

db_cooper · April 2021

@ScottG
I'm done with my attempted repairs of the connections and have put everything back together. I replaced most of the clips with screw type hose clamps, especially in the hard to reach places. I also doubled up with one at the end of the hose and another as close to the end of the connection as possible to keep the fluid from pooling between hose and outside of connections. I don't have any leaks and think 2 hose clamps is better than 1 clip. All of the corrosion I found started on the outside of the tubes, so I'm hopeful the boiler unit is OK.

I flushed one round of distilled water through the system, and got just shy of 2 gallons into it. When drained I still had some yellow glycol in the mix, there must be a bit in the boiler that doesn't drain, but not enough to worry about. I then got just shy of 2 gallons of Century fluid into it.

I'll be watching for hose bulges in the future, but until I have a leak or bulge those hoses are staying put. I'll do the full flush using this method every 2 yrs, and see how long she lasts.

On the broken tank connections, the JB Weld Plastic bond seemed to work great. You can't be gentle putting back together and it held together fine. I had to cut a couple inches off of one of the hoses to keep from putting too much pressure on the fitting. Part of the reason it broke was because of how much side pressure was put on the fitting when they mounted the tank. So much the tank deformed a bit. I clamped above and below the break, so even if it fails it shouldn't leak.

My best recommendation from this is to clamp your hoses to keep that fluid out, but that is a bit of a job in itself, so I doubt most will want to bother.

ScottG · April 2021

Sounds good @db_cooper. I'm glad things went smoothly and appreciate the update. It sounds like your experiences were very similar to mine in terms of trying to rinse all the glycol out of the boiler, and in terms of how much the entire system holds.

For good measure, I'm thinking of retrofitting all my convectors with a second (screw-type) clamp on the outer edge of the stubs.

ChrisFix · April 2021

Does anyone know if there have been any documented problems with corrosion using the Century fluid that has been changed every two years per the maintenance schedule?
I have a 2021 T@B 400 built in March 2020 that I'm trying to decide how to proceed with the Alde maintenance.
Should I bite the bullet now and make the expensive change to the Rho-mar Water or just flush and change the much less expensive Century fluid at least every two years (or more frequently)?
Is there any data that suggests changing the Century fluid more often, like every year, would prevent corrosion issues?

Sharon_is_SAM · April 2021

There has been at least one owner on the forum that did the glycol change every 2 years who has hose bulging. I think db_cooper changed his partially annually and he has corrosion. It may be related to extent of Alde use.

We are waiting to see how this plays out. Who knows, maybe there will be a recall that saves us some $. But, I understand that for those of you who have corrosion signs already or who are not close to a dealer, may want to do it DIY now.

ScottG · April 2021

@ChrisFix, I've moved your comment over here as it is more relevant to this discussion.

If you read back, you will see a mix of responses. One owner has changed the glycol as prescribed and still found telltale bulges at the convectors. A couple others who have done partial or occasional changes have reported the same. These were all 2014/2015 models whose Aldes got moderate to heavy use. I also got a report from an owner of a very lightly used 2014 whose glycol had never been changed but reported no bulges, so who knows what exactly is going on.

The sample is still pretty small. I'm hoping to hear from more owners of older T@Bs once trailers get pulled out of storage. Opinions differ on this matter but--taken together with the recent switch to the new glycol by both nuCamp and Airstream--I personally am not yet convinced that regular two-year changes will unequivocally prevent this corrosion from occurring.

The BIG question that has yet to be answered is whether the corrosion evident on the convectors is also affecting the boiler core. Convectors should be relatively cheap and easy to replace--not so much the core. The core is impossible to inspect without complete disassembly. I'm not aware of anly owners who have attempted this, and if the Alde folks know they are still not talking (at least not to me).

ChrisFix · April 2021

Thanks @ScottG.
From your research on this, do you think more frequent change-outs of the Century fluid would be warranted - like every year?
Thinking that is the route I'm going to take to give a little peace of mind (at least for the next year) while T@B dealers and nuCamp figure out the switch to Rhomar for pre-2021 production units.
I'd say I'm in the moderate to heavy use camp.

ScottG · April 2021

Good question, @ChrisFix. I doubt it would hurt anything (other than your wallet) but right now I have no idea if that would make any difference at all in mitigating the corrosion.

db_cooper · April 2021

@ChrisFix
If you have a dealer nearby that can do it right, I'd recommend biting the bullet now, or at 2 years, based on what I'm seeing.

I'm back to report the JB Weld Plastic bond did not work, and I found all the glycol drained out of the tank. The plastic bond was basically melted by the glycol.

If you ever have a glycol leak at the tank, do not be alarmed to find that it appears to drip out of the hot water drain pipe. At first I was panicked, thinking it had to have mixed at the boiler, but it ran down under the floor and out around the hot water drain.

I'm now trying to get a new tank, but can't get a dealer to answer the phone in their parts department. Good times...

pak · May 2021

I drained my fluid today and pulled one of the curved rubber hoses that connects one of the upper and lower heat exchangers. The exchanger ends looked brand new. Not a sign of corrosion. For the record. The fluid is original in my 2017 CS-S. We have about 20k miles on the t@b at this point. We have not used the alde for cabin heat very much, but do heat domestic water every trip.

ChrisFix · May 2021

@pak
That's good to hear. Hard to really know what the scope of the issue is, and what the root cause is.

pak · May 2021

Chris, you are absolutely on the money. I am the original owner so I know what has been in this system. I will go with the Century fluid for the next interval. Hopefully, Alde and NuCamp will have there arms around this issue soon.

Denny16 · May 2021

Yes Chris, we really do not know the actual cause of the corrosion in some TaB Alde systems. Blaming it on the Century TF- glycol is an assumption not based on any real facts, just because a different (apparently improved) glycol transfer fluid is being recommended.

Cheers

qhumberd · May 2021

Well said, @Denny16. I wish we could get the input of the Alde designers/engineers here to understand why the change was recommended. I must admit it is hard understanding the workings of the Alde from what is publicly available.

Denny16 · May 2021

Finding a product that increases the corrosion protection is reason enough, if yiur strive to improve your product. Does not mean or imply the previous system didn’t work well.
cheers

Lil_Lucy · May 2021

Denny16 said:

Finding a product that increases the corrosion protection is reason enough, if yiur strive to improve your product. Does not mean or imply the previous system didn’t work well.
cheers

In the Quality World, we called that “continuous improvement”.

Dalehelman · May 2021

Copied from another post of mine.

We are currently traveling in AZ. I was planning to wait till I got back to WA. State to inspect our system. Having nothing special to do today I decide to check it out today. Our T@B is a 2015 we bought it new while traveling Calif. so we have had it over 6 years. Traveled coast to coast twice been to the NuCamp rallys in Ohio twice. After inspecting all of the hose connections including in and out of the unit. All of the hose connections to the heating elements and overflow tank. I find that everything looks the same as the day I bought it. No bulging hoses or any kind of residue. I have never renewed the original fluid. I have add maybe a quart over the 6 year period. The trailer is used year round as we travel south in the winter. The Alde is used all of the time.
Can this be possible?

Denny16 · May 2021

Grand news Dale, glad you do not have any scaling or corrosion issues.

Well the Century fluid works, and protected your Alde system well beyond it shelf life.

It seems from what I’m reading here is, the Alde units that are used only seasonal infrequently seem to start having the corrosion issue, including the 2020 model that had some scaling. The Alde units that get used more seem to have little to no scaling or corrosion issues, like yours Dale. Perhaps using the Alde frequently keeps the glycol from getting trapped in the pipe fittings and getting stagnant?

Seems the Century TF-1 fluid is working quite well for you, and you should consider a good flush and refill with more Century fluid. As the old saying goes, if it isn’t broke, don’t fix it.

Cheers

fstop32 · May 2021

@Dalehelman, I am truly happy for your good fortune!

Denny16 · May 2021

It seems the TaBs that have the worst corrosion issues, are the ones used infrequently, and most did not keep up the glycol change every two years. But @Dalehelman posted in a different discussion, his frequently used Alde, a 2015 Tab with its original Century TF-1 glycol has no corrosion or scaling issue.

It might be the infrequently used Alde units, including one thst had its glycol changed very two years, are getting the corrosion issue. Perhaps the infrequent use, allows the glycol to collect and sit between the hose and pipe, causing scaling and eventual corrosion, as new fresh fluid is not being circulated to flush the fluid out of this area? Just a thought based on the observations in this discussion and the Changing Alde Glycol discussion.
cheers

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