Corrosion of Alde Convectors

Dalehelman · May 2021

6 years old never been replaced. ph is still 8.0

Denny16 · May 2021

That explains its appearance when you drained it. The ph only reflects the antifreeze component of the glycol, not the status of the corrosion inhibitors. Good luck with the change.
cheers

Sharon_is_SAM · May 2021

@Dale - can you take a photo of your Alde hoses?

ScottG · May 2021

Sorry to hear that, Dale. I've heard that degraded glycol can turn cloudy, but yours is the first actual report of it I am aware of.

My recently changed glycol--also six years old--was indistinguishable in all ways from freshly opened stuff, so your findings are yet another wrinkle in the glycol drama.

Century and other sources have repeatedly claimed that pH is indeed related to the effectiveness of the corrosion resistance, though a pH of 8 is probably on the low end of acceptable and may suggest the start of degradation. Most who have tested their Century glycol (including me) get a pH closer to 9.5. Whether there is something going on beyond what pH indicates has yet to be confirmed. In contrast, freeze protection is typically checked with a refractometer calibrated for propylene glycol.

Is there any chance the cloudiness you observed is a byproduct of being drawn through your shop vac?

ScottG · May 2021

Yesterday I set out to properly position the Alde's automatic air bleeder. In order to fit it in the provided plastic hanger, I needed to slightly separate the hoses on the aluminum fitting connecting the bleeder to the outgoing glycol hose.

With the fitting exposed, I tested its external surface for the ability to conduct electricity, and sure enough it had continuity (as would be expected from a non-anodized aluminum surface).

I might even open up one of the fittings in the near future to check the inside of the pipe, which definitely has a different appearance that suggests anodizing.

@fstop32, since your system is all apart anyway, can you test the inside of your pipes in an area that is not corroded?

BrianZ · May 2021

Thanks for the great info, @rh5555!
Great idea about the heat shrink tubing.
I just received a couple of these anodized 22mm aluminum connectors I thought I'd keep on hand if needed (shown here on an Alde 22mm hose)..

So, I just put the multimeter on it to check resistance and it was off the megaohm scale, as expected. Good thing, because they were expensive & cited their design quality & anodizing process meeting mil specs. So, if you need one of these, you're not totally dependent on Alde parts..
https://www.amazon.com/dp/B01GQVDCOC

I haven't started work on our system flush yet, but our side convector looks pretty good from the outside..

Image: https://us.v-cdn.net/5021717/uploads/editor/0a/qwvq1d2n87i8.jpg

We're approaching the 4-yr mark this fall & no glycol change yet. Our glycol tank level still sits just below the max mark, and we've never added any. Most of our camping has been right here in VA, a moderate climate, and we've probably only used the heater for heat or hot water maybe on a dozen trips. I plan to remove the rear storage cabinet & get a look at the rear convector hoses too. Haven't drained the system yet, but when I do, will remove a few hoses to get a look inside. I have some of the sealant on order, but I really like that heat shrink tubing idea, if needed, as the drying time for the sealant sounds like an inconvenience.

ScottG · May 2021

I'm looking forward to your report, @BrianZ. I think yours will be the youngest T@B to have the hoses removed and the stubs exposed, so may provide another clue to the disease progression.

Unfortunately--unless it's bad enough that bulges have formed--you really can't tell much from the external appearance. On most of my fittings the initial deposits and damage only extended up as far as the hose side of the clamp.

Image: https://us.v-cdn.net/5021717/uploads/editor/o2/qopspwxxbpub.jpeg

ScottG · May 2021

@Dalehelman, I know you said you had no leaks evident, but did you inspect (both by sight and feel) for any bulges where the hoses connect to the convectors or tother fittings?

Dalehelman · May 2021

@ScottG
On further inspection. I did find two hose with a slight bulging. See photo. As for leaking zero indication of any leaking.

Dalehelman · May 2021

Here is a picture comparing the 6 year old and unused glycol. Used on the left. The ph is the same with my test strips.

ScottG · May 2021

Thanks for the additional info @Dalehelman, even if it's not the best of news.

The upper bulge in your photo looks smallish, but the lower one seems like it's big enough to put some pressure on the clamp. As I suspect you have already determined, additional inspection and mitigation is probably in order, particularly with your full switch to a different glycol.

These last several comments are more about corrosion than the merits of the Evan fluid, so to try and keep topics from getting too fragmented I've moved them over the corrosion thread from their original location.

Dalehelman · May 2021

@Denny16
It is my understanding that glycol level determines the antifreeze level.

The ph level indicates acid level and corrosion protection.

Dalehelman · May 2021

@ScottG
Thank you

ScottG · May 2021

You're welcome, @Dalehelman. I don't generally tinker with other people's comments but right now we have three related but different interesting discussions going on about glycol and even I'm having a hard time time keeping track of them! ;-)

ScottG · May 2021

I think I might have to start keeping a spreadsheet on this topic, just like those frame cracks... :-/

db_cooper · May 2021

I would trade a frame crack for lack of corrosion.

pak · May 2021

My old glycol also was clear with a high ph. I removed one elbow to check for signs of corrosion and did not see any signs. I checked the inside and outside of the connvector and it has continuity. The connectors also have continuity. As it stands now I am thinking the problem, although sporatic, is due to the connvectors and connectors being raw aluminum. I am inclined, at the next change interval, to get new connvectors and connectors and anodize them. I suspect over the time of my next change there will be a lot more information available. Thanks to all for your inputs.

Denny16 · May 2021

OK, thanks for the update on the pH levels. I was going by what Alde had previously stated, that the Century fluid should be changed every two years, regardless of pH readings...
cheers

BrianZ · May 2021

Haven't yet drained our glycol, but getting closer. I wanted to first get the convectors exposed for inspection for corrosion later, so tackled the removal of the rear storage bin. Removing the 7 screws inside was easy, if you have a stubby screwdriver for the three inside the front. The whole bin then dropped down a couple inches. The only way I saw to lift it out of the tight space was by grabbing the two cross pieces of wood inside, but there was no room to do this while facing it. I had to lay on my back like I was bench pressing weights, reach up above my head to grab the wooden bars inside & lift. It was surprisingly easy this way, though you do need to rotate it forward & get out of the way to lift it all the way out.

Image: https://us.v-cdn.net/5021717/uploads/editor/bh/tv64ujdhyyuj.jpg

Be careful, because there is a piece of fragile styrofoam insulation on the bottom with a thin covering of aluminum, which serves to deflect heat up & away from the bin.
Then, I got photos of all the hose connections..

Image: https://us.v-cdn.net/5021717/uploads/editor/7z/01ct9t6jqzbq.jpg

Closer of hose connections..

Image: https://us.v-cdn.net/5021717/uploads/editor/yq/fppi9zurirsu.jpg

And convector connection on rear driver side..

Image: https://us.v-cdn.net/5021717/uploads/editor/kd/z4jl8kx9rjxc.jpg

And rear passenger side, where I noticed corrosion or oxidation on the outside of the bleeder valve..
I guess that needs to be cleaned up & coated with something to prevent air contact?

Image: https://us.v-cdn.net/5021717/uploads/editor/2q/45ijf86jayls.jpg

And closer..

Image: https://us.v-cdn.net/5021717/uploads/editor/z2/nzin9s2k9dn3.jpg

So that's all I have for now, until I get the system drained & can disconnect hoses for closer ininspection & test with ohmmeter if I can remember to do that. I guess I could test these new looking surfaces of the pipe connectors now for comparison, as a negative control. If it fails to give a high reading, then the anodizing by the manufacturer is inadequate to begin with.

ScottG · May 2021

@BrianZ, envisioning your contortions to remove that cabinet brought to mind your detailed tutorial on how to reach the back of the city water port through the bathroom wall hatch. I nominate you for the T@B University Endowed Chair in T@B Yoga. ;-)

I note that on the return line from the convectors to the expansion tank, you have a molded elbow making the bend into the tank. My 2015 doesn't have this. I wonder if this was done to alleviate stress on the tank return connector--a common location of cracks in early T@Bs.

Tabaz · May 2021

fstop32 - my Alde hose was also kinked at the bend. No question in my mind this is what caused the plastic nipple on the bottom of the tank to shear off.

ScottG · May 2021

Although I don't have the elbow, mine does not appear to be kinked. I wonder if it all depends on who was installing that day, how long the hoses were cut, and how they were run relative to one another.

T@Bs are physically very well constructed with top-notch finishes. I have noticed, however, that very little "artistry" goes into the layout of things like plumbing lines and electrical wiring.

db_cooper · May 2021

No elbow on our 2015 either. Looks like you will find some corrosion at the aluminum connections. Sorry to admit you to the club @BrianZ!

Dalehelman · May 2021

I am afraid that you guys are scaring the holy crap out of the hundreds maybe thousands who are following this thread. For those of you who do not have ability to perform or even understand some of the things that are being pictured and discussed here. Take a deep breath and relax. If your system is working fine and it is not leaking do not panic. My system is over 6 years old and the fluid has never been changed. Now everything they are doing is well and fine. IMHO some may be a little over kill. Since it seems almost impossible to find a service department that is willing and able to service our Aldes, and if they do we are talking hundreds of dollars. I would suggest removing the old fluid if it is over 2 years. Replace it with the original Century fluid. If you wish to change to the new type an extra step of flushing with preferably distilled water should be done. I have succeeded in removing my old fluid and flushing my system. Without removing the drain plug or disconnecting any hoses. I feel if they are not leaking leave them alone. Yes there maybe corrosion in the hose where it connects to the aluminum convectors. By breaking this bond you may need to replace hoses or convectors which are metric and probably very hard to find in America. I simply used a regular wet dry 1 1/4” or 1 1/2” shop vac. If you don’t have one you probably need one. By inserting the vac wand (you may need to shorten it) into the top of the return tank straight up a down it reaches the return hose connection. By Applying high volume low pressure to this hose the old fluid can be successfully removed from the system. By adding Distilled water, and repeating this process you can flush it as well. Then just replace with your chosen transfer fluid.

I AM NOT TRYING TO STEAL THIS THREAD IN ANY WAY AND I TRULY APPRECIATE ALL OF THE HARD WORK THAT HAS GONE INTO IT. I HAVE LEARNED MUCH FROM ALL OF YOU. I JUST FELT THAT MUCH OF IT WAS OVER MANY TAB OWNERS HEAD.
Please excuse the typos it’s not easy doing this on an I phone

ScottG · May 2021

The technical details that fascinate some of us are bound to intimidate others--I don't think anyone is advocating panic or trying to scare anybody. Concerned owners are welcome to join the conversation and ask questions, while those who are not interested are free to skip to next discussion. ;-)

Dalehelman · May 2021

@ScottG

I didn’t mean anyone was trying to panic or scare anyone. You must admit that many RVers are not big do it yourselfers. Some may even consider selling for fear of some major impending expense. I just want people to enjoy their unique trailers. If they are not having any problems just change out their fluid and move on.

ScottG · May 2021

FWIW, I agree with @Dalehelman's sentiment and advice. I've changed my fluid and plan to enjoy a business as usual camping season. I'll worry about problems if and when they become problems--which in my case may not occur in my camping lifetime.

That said, facts are facts, pleasant or otherwise. I hope the do-it-yourselfers here continue to ask questions and document their experiences. As Dale pointed out, that's how we learn. I like learning--it allows me to keep the unique trailer that I love running smoothly, to make reasoned decisions, and to advise others with confidence. YMMV.

BrianZ · May 2021

Well, recent posts express some of my mixed feelings about this project, as I'm in a quandary now about just how far I should go, and whether I could do more harm than good (either to my body or our T@B) by trying to clean & seal all the convector connections. And I assume there are other connector pieces, like at those elbows and on either side of the drain valve. I tried to disconnect the hose from the drain "T" going to the pump, but didn't have the strength or leverage to do it. I suspect it may be stuck by corrosion.

I have forged ahead with draining & flushing our system, and after flushing with both tap & distilled water, I went to what should be the hottest convector connection to see what it looked like..

So, it has started, but inside of the pipe still feels smooth, so now wondering what to do next. Clean gently with a wet rag? Use something more abrasive or would that just accelerate the damage? Or should I coat with the aviation gasket sealant, or something else. Or just put the hose back on & double clamp?
Let's see, we have how many of these, 8? I wonder if the hose-to-hose couplers are any better? Does anyone know what those look like or how they compare to these on the convector? The ones on the Alde were fine, even new looking..

And at check valve..

I think these convectors are just cheap & poorly made without proper anodizing at the connectors.
I can say that the 22mm automotive aluminum hose couplers I bought recently are much thicker with smoother edges than any of these connectors or those on the Alde, but expensive at $9 ea.

Not a whole lot inside the hose at the convector, and it wasn't difficult to remove.
I will probably look at a couple more & decide whether to keep going. Maybe will see what the sealant is like.
On a positive note, I at least got our system flushed and my new 3-way flush valve installed & used it for flushing, which all worked fine. Will post some of those photos later in the flushing topic.

Dalehelman · May 2021

Has anyone found any severe corrosion to the aluminum parts. Like holes, place’s there material has actually been eaten away. Or are we only talking about surface corrosion between where the hoses and aluminum are in contact with other?

BrianZ · May 2021

@Dalehelman, see the photo by @fstop32 from April 2 on p1 of this topic, among others.

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