Corrosion of Alde Convectors

fstop32

I think the first winter he winterized it but after that he would run the heat really low on nights it was going to get much below freezing.  He did some cold weather camping but not a lot.  I guess I would call it "moderate use".

DanWeitzel

Hi all. Just stumbled on this thread & have read thru all posts.  Went today to check my 2016 T@B and found some bulging on the top driver side connection of the rear convector.  Also felt but couldn't see a small bulge on the lower rear of the passenger side convector.  We purchased this T@B used November 2020 and I did the partial fluid change this spring.  At the same time in installed the anode rod and we did not use the Alde until this fall so there was no fluid circulation.  Interestingly you can see in the pic the degradation of the rod in just several months.  I've cleaned (sacrificial anode 4 pic after cleaning) & reinstalled the anode rod & will see what happens as we use the Alde for heating this winter (TX camper).  After reading these post I plan to drain & clean all convector connections & replace with new transfer fluid.  Until than I will keep tracking this thread for more suggestions. Also considering grounding all convectors electrically to the anode ground.  Any comments on that?

MuttonChops

=-= Rambling =-=

Gosh, reading this thread is concerning if not outright depressing.

Guess the real question is how wide spread is the problem?

Yes, all the systems are assembled with the same part numbers but it seems the corrosion is not occurring on all installations.  And how bad that corrosion is and it's impact on system operation is not clear {at least to me}.

So for now I'm going to be an Ostrich, with my head 'berried in the sand', by not doing a major/detailed inspection of the Alde plumbing.

In large part due to an 'undocumented' belief that most fluid change intervals are defined more by dealer service revenue than actual engineering data.

BridgerSunset

@DanWeitzel
I'm not qualified to say whether grounding every convector will help, but I tend to believe any electrical circuit is completed via the most conductive pathway.

Your anode pics are interesting, and make me ask these 2 things:
1.  Did the top of the buildup coincide with the top of the fluid level when the anode was hung in the plastic tank?
2.  Does the anode metal loss very much coincide with where the buildup was before you cleaned it?  

DanWeitzel

The area of the buildup was the submerged portion of the anode, so the top of the buildup is at the surface of the fluid.  Yes, the degraded area was directly under the buildup.   

DanWeitzel

Wondering if this aluminum 25mm tee would fit into the 22mm Alde rubber tubing?  When I redo my Alde system I would like to install the second low point drain between the rear convector & the passenger side one.  If something else would work better please let me know. 

https://www.hcspeed.com/products/25mm-od-aluminum-t-piece-pipe-hose-connector-joiner-spout-25mm-od?variant=39733222834337

ScottG

@DanWeitzel, 25mm might be a bit of a stretch, a based on my impressions of how stiff that hose is.

I can tell you when I was looking for such a tee some time back 22mm was a very hard size to come by. I did find a place that made custom aluminum radiator tees that didn't seem too ridiculously priced, but I never followed up with an order.

If you are interested I can try to find the site for you.

Freespirit

@DanWeitzel, on your particular set up, do you have one or two Convectors on the drivers/passenger side.

ScottG

MuttonChops said:

...

Guess the real question is how wide spread is the problem?

Yes, all the systems are assembled with the same part numbers but it seems the corrosion is not occurring on all installations.  And how bad that corrosion is and it's impact on system operation is not clear {at least to me}.

So for now I'm going to be an Ostrich, with my head 'berried in the sand', by not doing a major/detailed inspection of the Alde plumbing.
...

@MuttonChops. There have been relatively few reports of corrosion, but far fewer reports of "I checked my hoses and there are no bulges." Whether that means the problem is not widespread, or rather that owners are just not checking and/or reporting back, is not at all clear.

It's an easy enough thing to check either visually or by feel (though on newer models you might need to remove the little cubby storage to get to the rear convectors). My opinion is that if you find bulges you have deposits, and if you have deposits you will have some degree of corrosion on the outside of the aluminum convector stubs. Determining the extent of that corrosion does require disassembling and inspecting each of those connections.  

Given the current evidence--however limited--I'm sticking with the following assessment. This is mostly conjecture and is subject to change as more information becomes available:

• This is not caused by failure to change the glycol on a strict two-year schedule.
• This is surface corrosion caused by acidic or basic deposits in contact with aluminum surfaces.
• This is not galvanic or electrical corrosion. While installing a sacrificial anode or additional grounding of the Alde may help mitigate other problems, they will not by themselves solve this one.
• Switching to a glycol with a more neutral pH may reduce the corrosive effect. So may sealing the connections between the hoses and convectors.

I can accept that this may be over nuCamp's engineering heads, so they may be hesitant at this time to offer insight. I'm less convinced that is the case with Truma-Alde, particularly where this issue has surfaced alongside the abrupt recommendation to switch glycol formulations. In either case, I can understand why this might be kept on the down-low until the extent of the problem--and its solution--can be better determined.  

ScottG

@DanWeitzel, thanks for the picks of your anode. It's interesting that your deposits and corrosion look very much like those on the convector stubs (and quite different from what a typical sacrificial anode submerged in a hot water tank looks like). What's curious is that, unlike the hose-convector connections, there's no crevice to trap and hold fluid. It's almost like something about that surface promotes crystallization of the glycol and it's associated corrosion of the underlying metal. 

N7SHG_Ham

My guess is this is a widespread issue AND is not reported because folks don't check, myself included. On my 400 I have never seen the convectors, none are visible without taking things apart.

The Airstream service bulletin has the following right at the top:

Airstream and Alde are promoting a Technical Service Bulletin to replace the glycol in 2018, 2019 and early 2020 Classics to a new Alde fluid. The new glycol fluid has been improved for better performance. In addition to replacing the glycol, two grounds will also need to be added to the system. Some units may have one ground already installed.

Is there a possible electrical grounding issue causing the corrosion? The procedure Airstream is doing is to add two isolated grounds. One from the Alde boiler to the 12VDC panel and a second from the converter to the 12VDC panel. In the case of the Tabs I don't know the relevance due to the converter and 12VDC panel being integral to each other.

There has been zero mention of a technical reason to change fluid to the new type nor any grounding by NuCamp. In fact Nucamp has ONLY said new units come filled with the new fluid and have at least officially recommended no reason to update older units to the new fluid. 

I will be having my 2019 400 flushed and changed to the new fluid in February, about three years after manufactured date despite NuCamp not saying it is required. Personally I think this is probably an issue that shouldn't be ignored, at least the switch to the new fluid.

gulfarea

I have mentioned before, oil should be used in it instead of antifreeze. Your automatic transmission uses an oil to go to the radiator to be cooled and it is some kind of hot in the summer. Art

ScottG

@N7SHG_Ham, I doubt it's a grounding issue, but that is a pretty weak doubt.

Last summer I ruminated on the whole Alde grounding issue, as well as DC "grounding" in general. In short, it's complicated (at least to me) and simple answers were not forthcoming. I had some extensive PMs with a couple members, then threw the topic out for general discussion. Please weigh in if you have something to add! 

DanWeitzel

ScottG said:

@DanWeitzel, 25mm might be a bit of a stretch, a based on my impressions of how stiff that hose is.

I can tell you when I was looking for such a tee some time back 22mm was a very hard size to come by. I did find a place that made custom aluminum radiator tees that didn't seem too ridiculously priced, but I never followed up with an order.

If you are interested I can try to find the site for you.

Thanks, if you can find this site I would appreciate it.

DanWeitzel

Freespirit said:

@DanWeitzel, on your particular set up, do you have one or two Convectors on the drivers/passenger side.

We have a 2016 Qmax T@B - no wet bath in this model.  There are two convectors at the rear & two stacked vertically under the passenger bench.  None under the driver side bench. 

DanWeitzel

ScottG said:

@DanWeitzel, thanks for the picks of your anode. It's interesting that your deposits and corrosion look very much like those on the convector stubs (and quite different from what a typical sacrificial anode submerged in a hot water tank looks like). What's curious is that, unlike the hose-convector connections, there's no crevice to trap and hold fluid. It's almost like something about that surface promotes crystallization of the glycol and it's associated corrosion of the underlying metal. 

I was quite surprised by how quickly these deposits developed, in about 4 months with the Alde off and no pumping flow.  A point of interest, this anode rod is your standard RV water heater anode & has a steel core.  Not sure if introducing this steel core (exposed on the end of the rod) causes any issues (?).  The deposits were hard crystal like material which was not easily removed.  Also wondering if adding the anode might cause more problems than is solves. 

DanWeitzel

ScottG said:

@N7SHG_Ham, I doubt it's a grounding issue, but that is a pretty weak doubt.

Last summer I ruminated on the whole Alde grounding issue, as well as DC "grounding" in general. In short, it's complicated (at least to me) and simple answers were not forthcoming. I had some extensive PMs with a couple members, then threw the topic out for general discussion. Please weigh in if you have something to add! 

I have the anode rod grounded to the outside of the Alde case as suggested by Mark Turney on the T@B FB group.  Wondering if I should run a ground wire from this point on the Alde case to the trailer ground bar as well?

ScottG

@DanWeitzel, here is the site I mentioned. Let up know if you end up ordering something and how it works out.

mona

I have to agree that there are more units out there with corrosion issues, than what we see reported here on the forum. There are at least 2 pics on Facebook sites of bulging hoses and leaking glycol from splits in the hoses where the clamps are attached. Both of these are 2019’s. One of which has the biggest bulges I’ve seen yet. I’ve yet to see any discussion on Facebook sites about corroded convectors and bulging hoses. People are seeing bulges, but have no idea that they are not supposed to be there, unless pointed out to them that they have an issue, which I did on both pics. Or they simply do not know to check. The unit with the huge bulges is now sitting at the factory, along with mine, as we speak. 

Jeannie 

ScottG

Thanks for chiming in, @Mona. I remembered you had scheduled service quite some time back and await your report on both the corrosion issue and what nuCamp does to "ground" the Alde.

DanWeitzel

ScottG said:

@DanWeitzel, here is the site I mentioned. Let up know if you end up ordering something and how it works out.

Thanks for the link, I'll check it out.

BrianZ

@DanWeitzel, you probably already know this, but for a 22mm hose, the matching diameter is 7/8 in.

fstop32

@ScottG and @Mona, I too will be very interested in what nuCamp says and does relative to your corrosion issues...a 2019 is way too young to be experiencing such problems.

BrianZ

DanWeitzel said:

ScottG said:

@N7SHG_Ham, I doubt it's a grounding issue, but that is a pretty weak doubt.

Last summer I ruminated on the whole Alde grounding issue, as well as DC "grounding" in general. In short, it's complicated (at least to me) and simple answers were not forthcoming. I had some extensive PMs with a couple members, then threw the topic out for general discussion. Please weigh in if you have something to add! 

I have the anode rod grounded to the outside of the Alde case as suggested by Mark Turney on the T@B FB group.  Wondering if I should run a ground wire from this point on the Alde case to the trailer ground bar as well?

Yes, @DanWeitzel, I've been wondering about running a ground wire there too, but also in regards to what effect that would have on the voltage potential generated between our anode rod & Alde case, which I measured at over a volt when I installed mine.  I may try that & get some measurements, if I can get a break from dealing with all the fall leaves in our yard.
In regards to your earlier question about the steel bar inside the anode rod, I don't think there is any  adverse consequence there, for a couple of reasons.  First, magnesium is above both steel & aluminum on the galvanic chart, so should be protective of both for corrosion; and second, the cut surface area of the steel is tiny compared to the Mg exposed all over the rod, or the other metals inside the Alde, like the heater element, which I believe is a mostly nickel alloy.

Edit:
PS:  On second thought, the heater elements would not be protected if not in electrical contact with the anode rod or Alde cabinet.

mona

The T@b is back from the factory. The following is what was done. 

1. Ground was run from the convector behind the couch to the chassis, just as an extra precaution against the possibility of voltage getting in the system. 

2. New convectors, back and passenger side, and new hoses. 

3. The whole Alde glycol system was gone over, with no evidence of any kind of sediment any where else, except at convector/hose connection. So that’s good news. 

4. System was flushed, and switched to the new Rhomar water at my request.

The Century glycol that was drained out looked good and tested good. The bulges in the hoses were not there when the glycol was changed in 2019. In my case, why I had the bulges develop is still a mystery. Discussion is still on going between Nucamp and Alde/Truma, with no definitive answers as of yet, as to why some people have corrosion issues, and others don’t. Sorry I don’t have more to offer. 

Jeannie

fstop32

@mona, glad to hear you've got your T@b ready for the road again, and thank you for the update.

I'm curious how they attached that ground at the convector.  The mounting brackets on my convectors are just a "snug fit" situation, not a solid connection to the convector tube.

ScottG

Yes, thank you for the update, @Mona. That certainly adds a few more pieces to the puzzle (albeit a few more questions as well).

Grounding the rear convector (and only the rear convector) was certainly curious. I had expected the grounding would focus on the Alde cabinet in a manner similar to what Airstream was prescribing.

It's good to hear that corrosion and sediment is limited to the convector stubs (though I'm not sure if inspecting the inside of the Alde is even possible without dismantling the unit).

It also confirms my suspicion that nuCamp (and quite possible Truma/Alde) are aware of this vexing issue, but as of yet are still not able to explain it. That suggests--hopefully--that a resolution (or at least a bit of advice) is still forthcoming.

Either way, I'm glad your T@B is back in top condition!

Tabaz

Will be draining and flushing my friend's Alde to replace the corroded convectors and need to know how much glycol to order for the re-fill in order to have it on hand.  Anyone know?

fstop32

@Tabaz, not sure on a 2016 but my 2015 took about 2.5 gallons total.  I did remove the two small convectors under the driver side bench but I think nuCamp took those out anyway in 2016.  I was also changing to the Rhomar so I had totally flushed my boiler and everything else was new  so my system was bone dry.  I purchased a 5 gal bucket from Alde so the refill conveniently left me with just what I needed for the next flush and fill.

N7SHG_Ham

@Tabaz , I think Rhomar minimum size is five gallons, so you will have plenty.