Corrosion of Alde Convectors

GregChris · April 2023

Nu camp is offering a glycol flush and exchange for $345 for a 320, a little more for 400's, at the U camp23. They don't say whether it is for Century or Rohmar(not sure about those spellings). It also doesn't specify exactly what is involved, just that it takes 1hr at your site. I've heard Ucamp switched to Rohmar, also heard they still use Century, would be nice to know 1 way or another.

Sharon_is_SAM · April 2023

@GregChris - email nuCamp at Help@nucamprv.com and they will let you know. I suspect they will use the Rhomar as that is now being promoted as having superior anti-corrosion properties. Use of Century on a system currently using Century does not require a flush.

grassgd · September 2023

I found bulges in my hose at the Adle check valve. I fear the heat exchangers will be like the others pictured in this post.

I read this entire post and wish to thank a lot of people that have been working on this issue for a couple of years.

My takeaway is the root cause seems to be a crevice corrosion primarily due to no or improper anodizing of the aluminum parts.

The corrosion only impacts the inside of the aluminum pipe once it corrodes through from the outside under the rubber hose. The rubber hose creates a crevice for the corrosion to start but no corrosion would start if the aluminum corrosion resistance is sufficient to prevent this. The question of proper anodizing the outside ends of the connections in this case would be considered the root cause. The crevice exist by design but the anodizing of the aluminum, if specified by the manufacturer, is not being performed or improperly performed resulting in the lack of corrosion resistance. If anodizing is not even specified by the manufacturer, it's a design flaw.

I say this because when previously corroded exchanger ends that are serviceable are cleaned and protected with a heat shrink sleeve, then later found not to have no new corrosion seems to confirm the issue being the corrosion resistance of the original pipe OD not having the proper anodizing. This was reported by BrianZ on March 20 when he shows exchanger ends once cleaned and protected with a heat shrink sleeve and later see shoe not signs of new corrosion.

Unfortunately, it seems there is no response from nCamp or Adle/Truma that acknowledges the root cause and proper solution for this problem other than glycol fluid changes which does not solve what appears to be the true root cause. Owners that have maintained their system with fluid changes every 2 years still have this problem too.

My only suggestion, and what I will consider is using a 2 part epoxy coating on the any new aluminum parts that are in any crevice service. On serviceable parts, a pre-wash or etching to remove all existing corrosion and etch the aluminum prior to a 2 part epoxy coating being applied. If there is extensive pitting, Defcon epoxy for aluminum will be applied to provide a smooth surface before epoxy painting is applied.

The above is only my opinion after reading this post.

GregChris · September 2023

How much would stainless steel connvectors cost? The boiler is stainless, there would be no bi-metal interaction.

Mickerly · September 2023

The boiler being a different kind of metal with no corrosion makes me thing grounding/anode design is not the problem. I think it is captive chemicals between the rubber hose and the aluminum radiator. This is very similar to corrosion in modified cars with aluminum radiator where the hose connection is aluminum. Coating the aluminum would appear to be a good fix. Either a plastic coating or silicon grease.

ScottG · September 2023

This is a topic that has gotten fragmented among different discussions. Regarding the "crevice corrosion" hypothesis, there's some interesting info starting here. While I can not confirm or refute Mark Turney's claims, he does seem to offer an explanation that most plausibly connects all the dots in the Great Alde Corrosion Mystery.

Tabaz · September 2023

Thanks Scott for the link to Mark Turney's video. I found both Part 1 and 2 very interesting and informative. Best explanation about the corrosion problem I've seen to date. He also provides some simple solutions.

pthomas745 · September 2023

This showed up on the FB page the other day, from a quite disappointed owner. This is a "2021" trailer, that came with the Century glycol. So, we are assuming the build date is prior to Dec 2020, when the Rhomar change occured.

The owner had the glycol drained, flushed and changed to the Rhomar at "Nucamp last year". I'm assuming they changed the glycol during the NuCamp 2022 gathering.

And, now, in a trailer that is at most, three years old, even with a switch to the "new, improved protection glycol!" they have corrosion of the pipe coming out the side of the Alde toward the pump.

I would really like to know if Alde changed the manufacturing method of the convectors in the system, or the clamps used to connect the hoses, at the same time they changed the glycol product they require.

bergger · September 2023

I believe they have just recently changed to some type of plastic connector on the convectors. I can't remember where I read or saw that but will try to find it again.

ScottG · September 2023

The image above shows something quite different from the tell-tale bulges that typically appear at the convector stubs. I wonder if there is something else going on here.

Has the FB owner determined that the pipe itself is actually corroded. If so, has it eaten through the rubber hoses so as to appear on their outside surface?

Tabaz · September 2023

The last hose couplers I ordered from Alde were black plastic (previous order were aluminum). You can see the black plastic between the hose clamps, so those would not be the problem. However, I'm not sure if the pipe going into the Alde unit is stainless steel or aluminum. I agree with Scott, this looks like an entirely different problem.

pthomas745 · September 2023

@ScottG I will ask. There does seem to be a slight "bulge" in one of the hoses over the yellow valve. Just very hard to tell in a photo like this.

fstop32 · September 2023

When I was entirely rebuilding my Alde system back in Sept 2020 I was able to source all the parts through Truma/Alde and they sent me plastic unions instead of aluminum. I don't notice any bulging in the hose connections in the picture above (but then when I first saw mine they were already very bad.
One thing I did notice and mentioned it the thread way way back was the new convectors Alde sold me had tooling dents on one end of each new convector tube. This certainly would provide a space between the hose and the convector end where glycol could/would quickly seep in and start or assist in the corrosion process. It would be interesting to know if Alde changed any of their techniques for cutting the piping for the convectors so it didn't dent the pipe...?

The pics below are of the brand new (2020) convectors from Alde. It seems obvious their cutting process requires something to clamp/hold the pipe as it is being cut and it's leaving the depressions shown below. Normally the clamps are not placed right at the end of the pipe so it would be very easy for glycol to quickly begin seeping under the hose/pipe connection. The other end of both these convectors were a perfectly smooth pipe. Before I installed these on my T@b I cut the deformed part of the pipe off with my miter saw. The other thing I verified on my system was the worst of the corrosion was always at the dented end of the convectors.

Image: https://us.v-cdn.net/5021717/uploads/editor/fb/sme851k8ld1a.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/7y/00gexag0te22.jpg

DanWeitzel · September 2023

Here is what my union connector looked like. Replaced them with plastic ones from Alde. Convector stubs were in the same condition.

fstop32 · September 2023

@DanWeitzel, you may have done this too but I had to reuse the damaged long convectors in the rear so after cutting off the corroded ends I removed the same length section of the radiator fins at the end to give me room to reconnect the new hose.

DanWeitzel · September 2023

fstop32 said:

@DanWeitzel, you may have done this too but I had to reuse the damaged long convectors in the rear so after cutting off the corroded ends I removed the same length section of the radiator fins at the end to give me room to reconnect the new hose.

These are the straight thru connectors. I also had to cut off the bad ends of the convectors & reuse them as well. I have a set (four) of new convectors but what to keep them for when/if the old one ever completely fail. When I cut off the bad ends I than really cleaned up the stubs and added the heat shrink tubing. Then doubled clamped each stub. Did this in the spring, so far so good. This is a before pic of a rear convector.

Image: https://us.v-cdn.net/5021717/uploads/editor/8j/jnvnaajg5wyg.jpg

manyman297 · September 2023

I’m not sure if it’s been discussed before but are we seeing Alde systems with Rhomar glycol exhibiting this corrosion? In my searches on here and Facebook I haven’t run across any.

ScottG · September 2023

I haven't noted any corrosion complaints from owners who started with the new Rohmer glycol. However, that could be due to the relatively short time that Rhomer has been in use, or perhaps because of other changes (e.g., plastic vs aluminum connections) that may have been incorporated into the Alde system in the same time frame. Unfortunately, teasing apart all the relevant variables is difficult without complete information.

pthomas745 · September 2023

The photo posted above with the "corrosion" around the pipe outlet from the Alde unit was a 2020 trailer that had the glycol swapped to the Rhomar last year, and then has the issue in the photo.

AnOldUR · September 2023

pthomas745 said:

The photo posted above with the "corrosion" around the pipe outlet from the Alde unit was a 2020 trailer that had the glycol swapped to the Rhomar last year, and then has the issue in the photo.

Did I miss the details of this exchange to Rhomar? Who did the exchange? What method did they use? Was there any sign of corrosion present before the exchange? Is there a sample of what the glycol looked like after the exchange?

Speaking as also a 2020 owner who did the swap last year, it would be interesting to get some insight into how this could happen in one year.

pthomas745 · September 2023

@AnOldUR the photo above on my Sept 16 post is what I was talking about. Came from a FB post. (NuCamp Owner's Group). I'm still working on getting a bit more detail.

This is a "2021" trailer, that came with the Century glycol. So, we are assuming the build date is prior to Dec 2020, when the Rhomar change occured.

The owner had the glycol drained, flushed and changed to the Rhomar at "Nucamp last year". I'm assuming they changed the glycol during the NuCamp 2022 gathering.

And, now, in a trailer that is at most, three years old, even with a switch to the "new, improved protection glycol!" they have corrosion of the pipe coming out the side of the Alde toward the pump.

Image: https://us.v-cdn.net/5021717/uploads/editor/bx/zjytjycrftfm.jpg

BrianZ · September 2023

@pthomas745, That's a very unusual looking deposit on the rubber hose you showed above. I doubt that it could be coming through the hose itself, and would have to assume that it was fluid that either leaked out at the hose end connections, or leaked & fell from the exit hose above, then dried out. It looks as if the rubber hoses may have black plastic-looking connector pieces. Very curious, and the white surface-coating is reminiscent of the corrosion deposits we've seen inside of both convector pipes and the rubber connection hoses in our systems that had corrosion at the ends of our non-anodized aluminum convector pipes.
PS:
If the pump is moving fluid into the Alde from the expansion tank, then I also wonder what the inside of the expansion tank looks like - maybe there are deposits there too? (if for example there was insufficient flushing & the mixture of dissolved solids from old & new buffers resulted in precipitates coming out of solution). Or maybe it's nothing but a leak, since any buffer solution that dries out will leave behind some deposits of solid salts.

AnOldUR · September 2023

The reason I ask @pthomas745, is that there is a lot of variation in the way the exchange has been done, even among the different ways professionals go through the process. I though I heard that at uCamp they pushed out the Century with Rhomar, but didn't do a distilled water flush?

Also wondering if there's been corrosion in any of the systems that have never seen the Century fluid?

manyman297 · September 2023

pthomas745 said:

This showed up on the FB page the other day, from a quite disappointed owner. This is a "2021" trailer, that came with the Century glycol. So, we are assuming the build date is prior to Dec 2020, when the Rhomar change occured.
The owner had the glycol drained, flushed and changed to the Rhomar at "Nucamp last year". I'm assuming they changed the glycol during the NuCamp 2022 gathering.
And, now, in a trailer that is at most, three years old, even with a switch to the "new, improved protection glycol!" they have corrosion of the pipe coming out the side of the Alde toward the pump.

I would really like to know if Alde changed the manufacturing method of the convectors in the system, or the clamps used to connect the hoses, at the same time they changed the glycol product they require.

What I'm noticing in the photo is the torque applied to the three-way rubber hose that has the deposits on it. I checked mine and, while similar, isn't quite as "bent"...On mine you can feel the outlet on the Alde pushing against one side of the sidewall of the three-way hose fitting because the entire fitting is being pushed towards the rear of the trailer.

In this pic you can see some kind of rust ring right where that outlet's edge is...maybe it has broken through? So while it's not the corrosion issue we're referencing, maybe there's a leak in that hose allowing air in and causing the rust. Just a theory.

Sharon_is_SAM · September 2023

Regarding seeing corrosion following the exchange to Rhomar, unless they did a thorough inspection, there may have been pre-existing corrosion due to the Century. That’s one of those variables to which Scott alluded.

Fatman1966 · October 2023

I think mine are fine but this is the year I check them as a winter project. No bulges or leaks visible on the one under seating area. I can’t see the one in the back area. Mine is a 2017 and I’ve partially changed the fluid three times.
Two questions
1. How do I expose the back converter? How much or what part of the back area has to come out?

2. If mine end up bad what is the estimated parts cost for new convectors if they are damaged? I will do the work myself if I can get to the back wall area one.

manyman297 · October 2023

My understanding is it doesn’t ruin the convectors. You just have to clean up the corrosion but this is just what I’ve gathered on the forum. I have no firsthand experience with it.

Sharon_is_SAM · October 2023

@Fatman1966 - on our 2017 CSS, the rear convector hose is visible for inspection under the driver side rear bench.

BrianZ · October 2023

@Fatman1966
See page 10 of "Corrosion of Alde Convectors" topic..

https://tab-rv.vanillacommunity.com/discussion/comment/167199/#Comment_167199

I described removal of the rear storage bin to get to the rear Alde convectors.
P.S.:
This tip helped earn me a nomination for the "T@B University Endowed Chair in T@B Yoga. ;-)" from @ScottG .

grassgd · October 2023

As stated on September 16th, I see signs of corrosion at various places. Preparing to pull all hoses, exchangers, pump, etc -all except the main unit to assess, clean and repair all corrosion. As stated earlier I plan to clean corrosion with glass beading and using a 2 part epoxy coating on all metal ends (id and od) to protect from corrosion. Where there is severe corrosion pitting, will fill with Defcon for aluminum prior to epoxy coating. Plan may change once I get it disassembled.

I am ready to drain glycol out and rinse with water first then drain/evacuate the water before disassembling to avoid glycol inside the trailer.

Looking at the system it seems the simplest way to accomplish this is by dismounting the two passenger side (small) exchangers so they can be held in a vertical position higher than the reservoir to pull the end hose off to get access to installing 7/8 inch hoses to the two exchangers which are run outside the trailer to buckets- one filled with rinse water and the other to catch the glycol. The rinse water bucket will be set at a height to keep the reservoir filled while running the Alde pump which will then circulate water through the system until all signs of glycol are gone. This followed by a wet vac to pull the water out.

I know there are many ways posted to replace the glycol, but I cannot recall reading a procedure to simply get all the glycol out before disassembly. Comment? Is there a better way?

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