Corrosion of Alde Convectors

Freespirit · November 2021

@ScottG, I appreciate your quick response and I have read all the different steps previous owners have taken. Given this is a new TAB and less than 30 days out of warranty is this something I should contact nucamp about and put the burden on them for resolution, or just go about fixing the issue myself.

ChrisFix · November 2021

@Freespirit
I would definitely contact nuCamp's warranty department via email...copying links to this forum thread and sending them the photos you posted.

ScottG · November 2021

Given the age of your trailer, I agree about contacting nuCamp. I will be interested in their response.

fstop32 · November 2021

@db_cooper, it seems I failed to reply to your question back on June 12th about finding a source for longer hoses. I did...thanks be to Alde for selling me all the hose, elbows, clamps, Rhomar and other parts.
I believe I've heard that Truma/Alde is getting a bit better recently on making parts available, I certainly hope so.

Freespirit · November 2021

Curiosity got the best of me, so tonight I removed the box covering the Convectors on the passenger side to do a visual. Disappointment again. The top inside convector hose is bulging. Again not what I was expecting to see on a 2020 TAB after 1 year of use.

Cheers

ScottG · November 2021

Also not surprised. Those who have reported bulges have noted their presence in multiple places.

I'm curious as to how much you ran your Alde (for hot water and for cabin heat) since you have owned it. I don't know if degree of use is a contributing factor. At first it seemed that this problem was in part a function of age--@fstop32 and I both have 2015s. However, @BrianZ had some pretty bad corrosion on his 2018. Again, judging by the size of the bulges yours doesn't look too advanced, but on a 2021 with one season of use it's peculiar

Freespirit · November 2021

@ScottG, here is the break down:

93 total nights
64 nights with Alde heat( set at 60 degrees)
40 day/nights hot water

ScottG · November 2021

Yep. I'd say that's pretty heavy use. Again, not sure if that is a factor, but the admittedly limited data we have so far suggests that it might be. My T@B is much older, but I use my Alde very little.

Sneakle · November 2021

While replacing my expansion tank, I also noticed bulging in the hoses. Pulled them off to reveal corrosion. I cleaned off the corrosion with a wire brush on a dremel tool. There were granules of the corrosion inside the hose so cleaned that out as well as I could before reattaching.

ScottG · November 2021

@Sneakle, what year is your T@B? How much use does your Alde get?

Sneakle · November 2021

2018. Not a great deal of Alde usage.

Sneakle · November 2021

ScottG said:

@Sneakle, what year is your T@B? How much use does your Alde get?

Nowhere as much usage as Freespirit. I'm in the deep south. Have to look it up in my log book but maybe 15 to 20 nights of alde heat. Maybe twice that of Alde hot water use.

N7SHG_Ham · November 2021

I am going to have my 2019 400 flushed in February and install the new Rohomar fluid. I find it a bit odd that official advice seems to be carry on with Century in older models due to not having aluminum piping. It sure seems there is aluminum to corrode even if the piping isn't aluminum. It might not help prevent this by swapping to new fluid, but hoping it can't hurt.

A couple things have convinced me to do the swap, one is threads like this, two is Airstream swapping all customers on a recall.

ScottG · November 2021

N7SHG_Ham said:

...
I find it a bit odd that official advice seems to be carry on with Century in older models due to not having aluminum piping.
...

@N7SHG_Ham, I don't recall this being the official advice, or there being a change in the piping of newer Aldes.

Of course, I don't recall a lot of things... Can you point me back to the source of this info?

N7SHG_Ham · November 2021

@ScottG I would have to search, but a report to that affect has been mentioned more than once on either/or this forum and/or the FB groups.

I believe current thinking by at least Alde (Truma) is ALL systems should be converted AND the interval is still two years for changing even the new fluid.

When I have some time I will do a search and see if I can find the aluminum piping comments.

Edit to add a quote from NuCamp on a thread in the FB T@B Camping Trailers group from June of this year:

"Per Alde/Truma’s recommendation it should be changed, but the system would need to be flushed to do so. Because your unit has the rubber hosing used in models prior to 2021, you can wait to upgrade to the new formula when you do your routine maintenance."

I absolutely do NOT know why NuCamp would say there is not aluminum in the systems prior to the 2021 year campers, obviously they do have aluminum and obviously at least in some cases it is corroding.

ScottG · November 2021

Thanks, @N7SHG_Ham. Sounds like they did change something in 2021, but rubber hoses or not I agree there is still plenty of aluminum in the older units, including all the convectors and the flame chamber in the boiler core.

The comment about the "rubber hoses" is curious since it's the connection between the rubber hoses and the aluminum convector stubs that seems to be the problem area for these deposits and their associated corrosion.

So, do the 2021s not have rubber hoses connecting the convectors?

fstop32 · November 2021

@ScottG and @N7SHG_Ham, I can't speak to what is in the later model T@b's but I did find it interesting that when I received all the parts I needed to rebuild my Alde system (from Alde) they did substitute plastic unions for what had been aluminum ones in my 2015. However, as has been noted the worst corrosion was at the hose to aluminum connections on the convectors and not so much on the unions. So unless Alde is making plastic convectors there is still lots of hose to aluminum connecting going on...joking about plastic convectors

Freespirit · November 2021

If you choose to read this, it is loooooog, apologize in advance.

An update to my previous post on the 16th and 17th. I decide to continue with the century flush after talking with NUCAMP and several TAB dealers. NUCAMP is not committing to anything until a certified dealer provides a written analysis and documentation of what they find. I totally agree with this approach. I have made an appointment with a service department for the middle of December to analyze the Alde system and the bulges in the hoses.

WHAT I HAVE DONE SO FAR:

First step: did the glycol exchange as presented by @ScottG,(fantastic documentation and exceptionally presented, without your committed effort along with many others to this issue I would have never attempted this, for that I say thank you!), it went exceptionally well. Since I am not going back with century fluid I went straight to pumping 15 gallons of distilled water thru the system. The water was crystal clear after about 5 gallons but pumped an additional 10 gallons. Since I found bulges, I decided to do the complete system drain (Appendix A), I removed Convectors and hoses and will eventually replace with Rhomar (rhomar won’t happen until I hear back from NUCAMP/ALDE after service analysis).

To remove water remaining in the convector loop I followed Appendix A: Complete System Drain steps 1, 2, 3 and 4. I did not notice any additional water being forced into the expansion tank as a result of doing this step. Likely user error.

Next I removed the 2 Convectors on the passenger side. This went well. Removed the top convector first so any water would drain to the bottom convector. There was about a pint of water that I was able to capture in a small container. Next I removed the bottom convector and there was about a pint of water that I captured in the small container. With the 2 side Convectors removed and the two disconnected hoses elevated, I moved on to the 2 back Convectors. The 2 back Convectors came out with no additional water.

Now I went back to the two disconnected hoses (each hose is about 4 feet long) that run from the back Convectors to the side Convectors. They are on a natural slope (I would say 6-8 inches) from the back to the front of the TAB. ScottG indicated up to half the glycol in the system may remain in the convector loop and my guess was there was water captured in this valley. There was, about another quart of water. As noted above this was likely due to user error in following the steps 1-4 in Appendix A.

An interesting observation here was this water had a very light yellow/green tint to it (century fluid). While this water had a light tint to it, the 15 gallons of distilled water I flushed thru the system was crystal clear.

ScottG, what I am about to comment on is only that(IMHO) and likely only related to my TAB 320 configuration. A slight modification to Appendix A might be “complete draining is required if you plan on disconnecting hoses from Convectors AND if you plan on doing a complete fluid change over.

If someone is changing from century fluid to Rhomar and does not disconnected the hoses and drain them and remove the Convectors they run the risk of contaminating the Rhomar with century. In my particular example there was about 2 quarts of highly diluted century fluid remaining in the system.

I think the issue is that the hand pump cannot move enough volume of water thru the entire system at a fairly rapid constant speed to totally remove any diluted century/water trapped in the convector loop. There is simply not enough force to push trapped fluid up a 6 inch incline and out the discharge line. This may be the reason the ALDE flush system has two electric pumps with a low and high speed. I think to get a complete system flush without removing anything, you need to maintain a constant stream of water under pressure coming out of a hose of the same diameter as the ALDE hoses.

I have 4 Convectors sitting I’m my garage, disconnected hose in my TAB and a non-return valve somewhere. I will try to post some revealing pictures of everything tomorrow.

Cheers

BrianZ · November 2021

Good observations & suggestions, @Freespirit. I used an inexpensive 12V pump with a good flow rate (12L/m or 23s/G) to flush ours, and it kept things moving to push the glycol through without introducing air. It worked well with my 3-way valve for both flushing & refilling. If I use Century fluid again, I'll likely just push out the old with the new and use extra. I did flush well last time with plenty of both tap water & distilled, before the glycol, because it was 2 yrs overdue.

FYI, on p.4 of the Alde 3020 Service Manual, under "General Care of the Heating System", it says:
"Never allow the heating system to stand empty without ethylene glycol fluid." They don't explain what the concern is. One might think corrosion, but without the fluid, dissimilar metals wouldn't have a complete circuit, and oxygen allows aluminum to self-anodize, so those are protective things for the aluminum parts. Maybe they are concerned about destroying the boiler if it was inadvertently powered on?

ScottG · November 2021

Thanks for the detailed account, @Freespirit (and for your compliments on the DIY glycol exchange document--I'm glad it helped).

You make a good point about the flush not necessarily removing all the glycol from the convector loop. I didn't take particular note of this because when serviced my Alde I did a "benchtop" flush of my hoses only after removing them from the system. I also wasn't looking to change glycol at the time, so was more focused on cleaning up the deposits and corrosion and not as attentive to ensuring that every drop of the old Century fluid was removed.

I'm glad that you are willing and able to pursue this with a service call. You are the first I am aware of to do so, and I look forward to hearing what Alde and nuCamp have to say about this issue.

Freespirit · November 2021

Below are pictures of the corrosion I discovered in my 2020 TAB 320 U. Manufacture date 11/2019; took delivery 10/2020. These pictures are after using the ALDE for 1 camping season,( 1/2021-11/4/2021).

For reference my TAB has two Convectors in the back and two Convectors under the passenger side bench. Earlier pictures above show two bulges that were evident in the tubing, one in the back convector and one on the side convector but no indication from the other tubes of what lurked beneath.

ChanW · November 2021

Good photos @Freespirit. thanks.

It seems a little weird that the one end of the check-valve Is perfectly clean...

BrianZ · November 2021

@Freespirit, some of these convector ends look as bad or worse than some of mine which had seen 3 years of camping when documented this past spring.
I still can't help but wonder if any of this "corrosion" could be partly the Loctite sealant that was said to have been used during installation. That sealant is a whitish thick paste, which I also can't help thinking might create conditions for crevice corrosion.

ScottG · November 2021

@Freespirit, at a glance your deposits look heavier than what I found on my 2015. It's definitely reinforcing my suspicion that degree of usage--particularly of the cabin heat--may be a factor in how quickly this problem advances.

Despite the age of my system, I can probably count on one hand the number of times I've run the cabin heat--and only one of those times was it run for an extended period (such as overnight). Even hot water only gets fired up once a day for an hour or so.

fstop32 · November 2021

First observation: @ScottG, you need to do more spring and fall camping, you don't know what you're missing!

A few things seem consistent, generally speaking...a) the direction of glycol flow into a convector seems to result in more corrosion, pretty sure that includes the union at the check valve, b) several of those ends pictured have the tooling marks present which I think contributed greatly to which ends of my convectors had the worst corrosion, c) high usage of the heating system seems to be a factor.
I am shocked that a 2020 would have this much corrosion. I can almost go along with a major heating system overhaul due to corrosion every 5 years or so, but after one season even with a lot of use needs to be a huge wakeup call to nuCamp.
@BrianZ, have you pulled a hose on one of your "heat shrunk" convector ends yet to see how it's doing? I'm planning on inspecting those ends when I give the "escape pod" a rest in January. I did your heat shrink on all my convector ends when I rebuilt it last March/April, I'm anxious to see how they are holding up.
@Freespirit, sorry you've encountered this so soon. I'm sure you've seen the previous posts from BrianZ on his heat shrink approach and clamp placement, and back on page 13 I had a short dissertation on shortening the unrecoverable ends on a convector by shortening the fins and chopping about 1.5" off the tube end.
Be not dismayed, all is not lost!

BrianZ · November 2021

No, @fstop32, I don't plan on messing with anything I've done recently on our Alde fittings at least until we're due for a fluid exchange a year from next spring, and maybe not even then. The only other thing I've done on our Alde since spring (when I added a 3-way ball valve, cleaned all the hose connections, convector ends, coated them with conformal coating, and added adhesive heat shrink tubing) was to add a magnesium anode rod to the expansion tank in September, with a ground wire connecting it to the Alde cabinet, in hope that the sacrificial anode will help prevent general corrosion in the Alde system. I replace anode rods in our home water heater every 5 years & flush the tank every one or two years, so I may do a periodic drain of some glycol using the Alde drain, in case some anode rod sediment collects there. The rod in our water heater definitely generates some sediment as it corrodes, which flushes out when I drain the tank. This is all really experimental, but is meant/hoped to address any general corrosion throughout the Alde glycol system. Interestingly, and as noted by the originator, the galvanic potential between the anode wire (soldered to the sacrificial anode immersed in the glycol) and the Alde cabinet (where the wire is connected) when measured with a voltmeter is more than one volt, like 1.3 or something, as I recall. I measured it & was surprised, even though I was expecting it. Hoping not to deal with any corrosion issues or maintenance for another 1.5 years. Not that I won't be curious what it will look like later on, I'm just not looking for any more work any time soon!

fstop32 · November 2021

@BrianZ, I ordered an anode rod a few days ago and planning to do the same thing

ScottG · November 2021

@ftop32, I do enjoy spring and fall camping--even more than summer--and do it as much as my pesky employment and the seasonal availability of northerly campsites allows. I also like sleeping at temperatures in the mid 50s, and have found that a body or two in that little space tends to keep the temp at least that high. If I ran the Alde any more than I do, I'd bake myself right out of the camper! I break a sweat just reading about owners who like an indoor temp close to 70! :-)

I agree with you about the direction of glycol flow probably being a factor as well as usage, since the "upstream" connections are better positioned to catch a bit of fluid between the hose and the stub. Regardless, with enough time glycol will manage to find its way into all those crevasses.

With regard to my own situation, I decided that while I would keep pursuing answers, I wasn't going to lose a lot of sleep over the corrosion issue. I'll check for bulges annually, and clean up or replace parts--and perhaps employ some of the clever solutions proposed in this discussion--when and if I need to do so. So many other things could go wrong in the interim (with the camper and with me--ha ha) I think I'll just focus on enjoying camping while everything still works! :-)

fstop32 · November 2021

@ScottG, I like your approach to the issue. And I was just razzing you about not running the heater much

We prefer it cooler for sleeping too. I think I've noticed that the camper heats up more quickly with that little floor level fan I installed to push air through that middle beam I built to the back convectors. Maybe that will mean my heater won't have to run quite as much as before.

ScottG · November 2021

@fstop32, I may have asked this before, but did you ever get a sense of how much the previous owners ran the Alde (particularly the cabin heat)?

Corrosion of Alde Convectors

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