Corrosion of Alde Convectors

TNOutback

When I posed the question to the Alde rep, whether to continue with the Century fluid upon my first change or switch to Rhomar, she said switch to Rhomar.  I’m really not surprised by that answer, but I’m inclined to go with the OEM’s recommendations.  If there is ever a problem in the future, I don’t want to give them an out by saying I didn’t follow their recommendations.  No idea where to get that done though.

Denny16

You could always call nüCamp and ask, or schedule an appointment with them to switch out the fluid.
cheers

MarkAl

With @Dalehelman wet/dry vac tech of glycol removal and adding a thin coating of appropriate grease on the all the slip fittings I'm ready for my first exchange next year... of course it is a year away. For sure I'm not spending $400 to have someone else play in Sm@ll World. I figure the grease will be a one time application though.

ChrisK

You folks want a "hold my beer" corrosion pic?


This is what I found last October after removing the hose after finding fluid in my storage area. This is the rear convector. The lower fitting was pretty bad while the upper was almost new looking. I'm pretty sur it was because the hose coming out was bent in to a 90 degree almost closed bend to get it to go through the hole in the bulkhead. The top hose went through the blender valve thingy which made the turn properly. 



This is the lower hose. It was completely bent closed to make the turn. It was also very bulged. The other hose was not. I communicated with NuCamp and they contacted Alde. All they said was that I needed to replace the convector. No word on the actual install. Believe it or not, I cleaned up the convector pipe, got rid of any protruding sharp bits found I had enough to reattach a hose. I replaced the hose and installed a 90 degree fitting for the bend (sorry, no pic of that. Just wanted to get it done). I check it regularly for leaks. I'm pretty sure the pressure caused by the folded over tubing caused a slight leak in the joint between the hose and the convector fitting and, over time, the aluminum wore away. We always had Alde fluid loss and I just assumed it was normal evaporation out of the vent line. Never showed up in any of the compartments or on the ground. 

I will eventually replace the convector but it is working for now and I'm going to get my moneys worth out of it.

ScottG

That's gruesome, @ChrisK. It's interesting that the other stub was still perfectly clean. I think you are on to something in that the degree of corrosion is related to the amount of fluid that seeps between the hose and the stub (a situation that in your case was exacerbated by the extreme bend in the hose).

The hoses in my 2015 are configured in the same way, but no kinking was evident. I think I have a bit more clearance between the end of the convector and the hole in the partition. perhaps they went to a slightly shorter convector in later models.

Regardless, I'm glad you got yours patched up and working again--I agree about getting your money's worth!

Did you notice bulges at any other fittings? How much use has your Alde gotten over the years? Has the glycol been changed?

BrianZ

Wow, @ChrisK, what contrast between those two.  Probably the best (or worst) example of crevice corrosion that we've seen, or maybe second to that of @fstop32.  Amazing that you were able to salvage the convector.  Like Scott, I'm wondering about the glycol change history on your unit.

ChrisK

Our camper gets used at least once a month and this year, mostly twice a month. I only fully changed the fluid last year during this repair. Like I said though, it regularly got new fluid due to the phantom loss. The fluid that came out during the repair didn't look that bad. 

fstop32

Alde makes 90 degree and 180 degree molded hose elbows.  I'm having a hard time understanding why someone would install a straight hose in a spot that is going to be compromised from the get go and want to collapse at that bend when it gets hot.  It would have been sooooo easy to pop in a 90 elbow when they outfitted the camper...  @ChrisK, maybe you can get NuCamp to procure you a couple of those from Alde so the next time you're that deep in there you can make it proper.  That was a gnarly looking stub, I had three that looked that bad in mine so I feel your pain.

Tundra57

I added an extra convector underneath my tab 400 a year ago. So the fluid got changed then about a year after new.

Everything looked pristine then. Still looks good now. But you have all scared me into regular 2 year fluid changes. I missed the thread on the new Alde fluid. Can it replace the old century green stuff?

TNOutback

Denny16 said:

You could always call nüCamp and ask, or schedule an appointment with them to switch out the fluid.
cheers

I did just that, and I lucked into a canceled/open appointment slot on Friday.  Double luck in that I had a friend tow my 400 up to Sugarcreek on his way to pick up his own camper after a service appointment.  I picked up my camper yesterday.  I expect I will do all future glycol changes myself, but after reading all the posts on this topic, I just wasn’t comfortable I could get it all the Century fluid cleaned out properly and have a way/place to dispose of the waste

Sharon_is_SAM

@TNOutback - what fluid did nuCamp use?

TNOutback

Sharon_is_SAM said:

@TNOutback - what fluid did nuCamp use?

@Sharon_is_SAM I specifically asked Austin for the Rhomar Water flush/cleanse/refill.

fstop32

I know everyone has moved on with their lives and campers but I thought I'd post this as a FWIW tidbit...on the new convectors I recently received I immediately noticed some tool marks on one end of both convectors where the aluminum pipe had been clamped and cut during production (see pic).  I couldn't help but think that irregularity could provide an easier route for glycol to get in between the hose and the outside of the aluminum tubing where the clamp is located.  My idea was to put the convector on my miter saw and trim off the 1/8" or so to eliminate the damage and get back to a smooth surface.  That was very successful, gotta love those carbide tipped blades.  Then it hit me...I had noticed that on each of my old convectors one end was badly damaged by corrosion and the other end either not so much or really not at all.  I reexamined all my old convectors and found that every badly damaged end had the same tooling/cut marks (see 3rd pic).  
I'd be interested to hear if anyone else thinks these tool marks might have encouraged the crevice corrosion by more easily allowing the glycol a path to work it's way under the hose and sit in the small depressions...???

 

rh5555

@fstop32, I think it is very, very likely that these tool marks are a contributing factor.  Good observation!

BrianZ

@fstop32, I think your hypothesis is a very likely contributing factor.  If you could somehow anodize the ends after cutting, that would be even better.  At least or in addition, coat and/or cover them with something appropriate as previously described.
I saw some of those marks on ours, but didn't know what they were.

fstop32

I only have 2 new convectors so far and I've trimmed the bad ends on both.  I'm letting them anodize naturally while I'm waiting on the remaining parts.  I've looked around here trying to find some place that could anodize the ends for me but no luck so far.  I might get motivated enough to try to do it myself, if not I'll definitely be doing something on those convector ends before installation.

BridgerSunset

Nice observation @fstop.     Likely part of the equation.
Which make me curious - and maybe I missed it along the way - but can you say that the direction of glycol flow - into or out of the convector -coincides with the worst or least corrosion?   Wondering if incoming flow hitting squarely the convector end, versus the outgoing flow just flowing on past the outgoing convector end has any bearing on anything.

ScottG

I hadn't paid particular attention to this when changed my glycol (and dismantled the system), but looking back at the photos I took it looks like some stubs had the tooling marks and some didn't. 

I noticed no obvious association between the tooling marks, the direction of flow, and the degree of corrosion.

fstop32

@BridgerSunset, there does seem to be a correlation between the direction of glycol flow and the joints which had the worst corrosion.  I drew up a schematic of the system before I began disassembling so I was able to mark on that schematic each bulging hose location as I found them.  The worst locations were where the flow was coming into the joint but there were two where the flow was going out of the convector and one of those was one of the larger bulges.  
Another observation I made which I failed to mention above was that the bulges and significant corrosion was always on the convector ends and not the short aluminum "unions" between hose sections.  I looked at those short unions yesterday and none of them had the machine tooling/cut marks, they were all just short smooth pieces of aluminum pipe...which would seem to support my "machine tooling/cut mark corrosion theory".

ScottG

@fstop32 and @BridgerSunset, I did see the start of some corrosion on at least one of those aluminum unions (which also had no tooling marks.



These are good observations, however, while the tooling marks and glycol flow direction may contribute to the problem in some cases, I suspect they are red herrings with regard to the root cause of the corrosion issue.

BrianZ

I'm also still wondering whether any of the white looking deposits are all corrosion, or if some of it could be the Locktite sealant which contains talc and quartz, or whether anyone has even found any kind of sealant on non-corroded pipes.

fstop32

@ScottG, you are correct that the tool marks are not the root cause of the problem and I was not declaring them as such.  In my mind the tool marks and depressions from the manufacturing process did enhance the speed and spread of the onslaught of the cancer.  I think it is entirely possible that had the convector tubes been as pristine as the unions that I might have only been looking at connections similar to the one you just posted.  Most of my unions had similar light corrosion which were easily cleaned.

fstop32

FWIW...I took one of my old convectors and potentially gave it some new life.  I took the mounting bracket and about 1-1/4" of the fins off, trimmed the stub and put the mounting bracket back on.  This does leave one with a shorter convector and the difference would have to be made up with a longer piece of hose.  I'm still crunching the numbers on what the lost heating capacity would be...but who really cares about that 

  

BrianZ

Wow, great idea, @fstop32!  I guess all those fins & bracket are just held on by friction.  Nice to be able to salvage the good part.  Seems to me the only difference would be a very slight reduction in "mpg", or btu per $ of kWh or propane usage.

rh5555

@fstop32, have you considered this? https://makeitfrommetal.com/how-to-anodize-aluminum-at-home/

db_cooper

@fstop32
I'd be interested in doing this next time I replace the fluid (if I can't source new convectors).  Have you found a source for longer hoses of the appropriate material?  

fstop32

@rh5555, I actually have but I'm getting pushed to at least have the camper ready for a July trip (even if I don't have the boiler back in place) so I'm not sure if I'll have the time to research, purchase anodizing stuff and make it work in time to button it back up.
@BrianZ, the mounting brackets and the fins are just a snug fit to the pipe.  If you just needed to shorten a little bit you could just scrunch the fins a little closer together and not even take out a section.  You just wouldn't want to restrict the air flow.

RCB

I stopped following this thread after I renewed the Century fluid. I now wonder if I should have worked a little harder and replaced with the new blue fluid. Probably !

With regard to adding shrink tube or silicon grease (?) to the ends of the convector tubes; I think a coating of epoxy would provide a suitable barrier to protect the aluminum. I would also coat the exposed end of the tube and 3/4” or so of the interior of the alum tube. As well a doubling of the clamps with one placed close to the end of the alum tube and the second immediately adjacent, would help prevent the migration of fluid between the alum and flexible tubing.

Freespirit

@ScottG I have been actively following the thread related to changing out the Alde fluid. Started the process today and decided to remove the back shelf in my 2020 TAB 320 U to get a better view of the glycol tank. Much to my disappointment I noticed a bulge in one of the aluminum pipes/hoses connections. 

The manufacture date of the trailer is 11/2019 and we took delivery October 2020. This would be the first scheduled century fluid flush and replace. The Alde has worked flawlessly and never had any issues. 

With this new found issue I am not sure what my next steps should be. Any suggestions, advice, foresight, next recommended steps would be appreciated.
For now I have halted my century fluid flush pending what I decide my next steps should be.
Cheers. 

ScottG

@Freespirit, I've moved your comment from Changing out the Alde fluid over to this discussion as I think you will find it more relevant to your particular circumstance.  

I'm sorry to see you have found the dreaded bulges, and in a newer T@B at that. Fortunately, they don't look too big so my guess is you have some deposits on the stubs under the hoses, but not yet so much corrosion that the stubs themselves should be compromised.

If you read back through this discussion, you will see there was never an official resolution or explanation for this. Some affected owners (myself included) dismantled the connections and cleaned up the stubs as best as possible. Other took (or at least considered) more aggressive strategies to prevent further corrosion. There's lots of ideas here, if no definitive answers.

Once I got my convectors cleaned up, I put everything back together and just went ahead and replaced the glycol with the same Century TF-1 that was originally installed. If you were looking to flush and refill with the new Rohmer Water I have no idea whether the existing deposits/corrosion would be of any concern.