Corrosion of Alde Convectors

BrianZ

@BridgerSunset, I got the reading you requested:
It was +0.38V.
That was taken with a black alligator clip on the aluminum mount at the end of the convector under the passenger side bench seat (far end of the glycol loop).  The anode wire was "grounded" to the Alde cabinet, on a screw that I had previously found was +0.06V above the ground bus bar.  The Alde was on DC power with glycol circulating, but no heat, about 42° ambient temp.
Will be interesting to hear if you can make any sense from it, or maybe useful nonsense?  I still need to post my other various voltage measurements, which might help you for context in my setup.

BridgerSunset

@BrianZ
Thanks for all your work.  Every piece helps.  I'm unable to say what should be happening.

So do we know if the Alde cabinet is steel or aluminum? 

Your 380 mV reading isn't that much different from @Dutch061 when he tested potential between convector & ground with anode not being grounded.  I gotta think about that for a while....

Passport

There is a complete Alde system incl controls for sale on Facebook Marketplace within 250 miles of Oklahoma City.  It came out of an Airstream Classic.  Alde 3010 RV Hot Water Heater System + Flow Addition for Airstream/RVs. It may be too large for a small T@B or NuCamp.??

$500 + shipping.

Denny16

The model of the Alde might not be correct, as the Flo only works with the Alde 3020, not the 3010 (one of the main differences between them) from what I understand from Alde when I looked into adding a Flo tank to our TaB 400.  I would double check this add.  The Airstream uses the same A
de system as thenTaB, so it would fit.  For $500, it would be good for spare parts?  

Cheers 

Parlando

After calling the only T&B dealerI could find in my area (2 hours away), and getting a quote of $550 to flush and refill the ALDE, I was thinking of draining my ALDE, then flushing with water. Reading these post it sounds like the next step would be a low volume air compressor to blow out any remaining glycol. Where and how would you attach the compressor hose?     Also, I called Truma and they said that draining the ALDE would be a crazy decision that would risk ruining the $3,000 heater and other plumbing in the T@B. I’m reasonably able to do carpentry and most household repairs, but this has me confused as to what to do.  

Freespirit

@Parlando, are you planning on replacing Century fluid with Rhomar or are you just doing a drain/ flush and replace with same fluid, (Century/Rhomar)?  Will you be doing this on a TAB 320 or 400?

pthomas745

At the bottom of this Alde set of info is a whole rundown of one way to do this job. 

https://tab-rv.vanillacommunity.com/discussion/7722/alde-manuals-and-resources#latest

If you really want to get the rundown of all the different thoughts on the Alde exchange, try sifting through this really long thread where several different methods are proposed.  The Forums have done quite a bit of work on this.

https://tab-rv.vanillacommunity.com/discussion/2665/changing-out-the-alde-fluid/p1

BrianZ

@Dutch061, back on the last page, you had suggested here..

https://tab-rv.vanillacommunity.com/discussion/comment/180960/#Comment_180960

..that I should do a voltage drop test between the Bus Bar Ground, the Frame, and the 120 VAC Ground.

I'm a bit late, but here are those results..

Also, here was my repeat your measurement of current between Alde & ground..

You had also suggested doing a voltage drop test between the Bus Bar Ground and Negative Battery Terminal.  I got zero millivolts.
This may be of interest to you too, @BridgerSunset.

BridgerSunset

Getting too far into this🤔 for my skillset.....

My take is this:    these readings show that there's a higher voltage potential when grounded to the Alde case ( or DC ground) than to wherever the AC ground is connected to.  Does it imply the DC ground is connected better to the steel frame, and the AC ground is connected more to aluminum?

Just my layman's speculation again that we are simply reading the natural voltage difference between metals.  Whether current is being useful or harmful, not sure.  I'd  be inclined to ditch the anode project unless Truma can vouch for it.

rcarlson1957

@BrianZ I experienced the dreaded expansion tank nipple crack. Talked with tech at NuCamp at T@bzona and he said it's due to stress on the hose from the convector to the expansion tank nipple. Said they use a 45 degree elbow to relieve the stress. I ordered the parts and also the replacement elbow for the passenger side that has the long manual bleed valve. The existing one is way down at bottom. Got the parts in I got a rubber T, a 45 degree elbow, a 45 degree elbow with the long manual bleed valve and the expansion tank. I assume I have I have to connect the 45 elbow to the expansion tank nipple and then cut the hose coming from the convector and join them. But they didn't send anything to do that. Assume need aluminum pipe. Also have no idea what the T is for. You mentioned a 3 way flush valve. Do you have a pic? Thanks.

rcarlson1957

@Dalehelman I'm in process of replacing expansion tank due to nipple crack. You mentioned you drained liquid with wet/dry vacuum. Where to you connect it? Did you have to pull the plastic alde glycol plug underneath the camper? When it cracked, I disconnected the hoses and put baggies over them with clamps till I could get the parts in. Also, 2 other things if not too much trouble. 1 - How many gallons of glycol did you need? 2- How did you flush the system with distilled water? Thanks!

ScottG

@rcarlson1957, you might want to spend some time perusing this lengthy discussion. There's a lot of esoteric stuff you can probably ignore, but the answers to your questions--as well as numerous alternative approaches--are in there somewhere.

MarkAl

As an Electrical Engineer I was intrigued by this discussion of ground currents. On my rig which is a 2021 model but built right when the factory returned to work from Covid. So I believe it has only "new model" issues not supply or capacity issues. BUT I see a consistent 6 mVolts of ground difference between the Alde and ground strip by the converter with almost the same to the battery ground (note I have a Smartshunt so it will be slightly higher depending on current flow).  I measured it w/o external power with propane and 120V connected and heating on electrical. No difference, my outside ground is connected directly to this strip also.

I do believe this could be a factor in the corrosion and be part of why the systems are corroding so differently.  Though I also think the main reason is the poor sealing of the clamp to convector pipes trapping the fluid in the joint.

I also noticed that unlike a car where all metal parts are well connected to the system ground the trailer probably due to all the plastic has many parts with much higher ground currents. Not great for safety if running from shore power and there's a short from power to ground. But what the hey, we're camping we could get hit by lightning or...

fstop32

@rcarlson1957, when I rebuilt my heating system I was able to source 90 degree hose elbows with 6"-8" leads before the actual bend.  I cut them down to fit between the convector and the tank and avoided extra union connections.  You can also get unions to make the cut & splice as you mentioned.  My 2015 had 2" aluminum pipe for those unions but I believe nuCamp's supplier is now using plastic unions (which is what I used in my rebuild).  If nuCamp doesn't have those you might try the manufacturer.

RMo

Quick question.  I’ve checked the connectors on the Alde unit and in the bathroom and found no sign of swelling.  Should this give me any confidence that there is not a problem?   Does the corrosion usually show up on all connectors or is it usually more arbitrary?
thanks.

ScottG

I found the corrosion on the convector stubs occurred everywhere, but to varying degree. In some cases there were bulges, in others, there was nothing to see until I removed the hoses from the stubs.

Freespirit

@RMo, on page of 14 of this post you can see pictures showing the various degrees of corrosion on all 4 of our convectors. Some hoses had bulges others did not. 

Parlando

@Freespirit  Sorry for my delay in answering your question.  I have a 2015 320 Outback.  Purchased used with no maintenance history.  I would prefer to simply flush and replace the Century fluid, but I'm concerned that might not be enough to prevent corrosion.  So I'll probably be replacing Century fluid with Rhomar.  My closest dealer, Apache in Portland Oregon was charging $550, but now say that will only work on rigs that they sold.  And the two other RV places they recommended said that the flush would run $1,600 and $1,100.

Parlando

@ScottG   Thank you for the pointer to the diagram and instructions for doing a DYI flush.

Freespirit

@Parlando, there are several alternatives described for a DIY flush, I am sure all work equally well given your personal preference. I chose to use the DIY flush and fluid replacement as documented by @ScottG. I followed his suggestions, took my time, it was 100% successfully. While I would never encourage anyone to undertake a project they are apprehensive about, with a little planning, taking your time, and your experience ( carpentry, household repairs) I think you can expand your TAB knowledge base while saving $$$$$. 

fstop32

@Parlando, that'll be $350 paid in bitcoin to @ScottG...     just kidding!  
@RMo, I, like @ScottG, found corrosion to some extent at all hose to aluminum connections with the exception of the connections directly to the Alde and the connections on either side of the "flow assembly" (the automatic air bleed vale with the small rubber hose running to a drain port).  As @Freespirit point out there is a lot of good info and pics throughout this post that can be helpful in diagnosis, repair, replace, testing, you name it.
If you decide to change to the Rhomar fluid I would suggest you pull a couple of hose connections to check for corrosion while you are into the changeover process just so you know where things stand at that point in time.

RMo

Thanks guys!  I'm feeling better but I'll still look more closely.

Any info on the percentage of T@Bs that have this issue?

ScottG

RMo said:

...

Any info on the percentage of T@Bs that have this issue?

It's been reported here by several owners, but no real data on percentages as we don't tend to hear from those who don't have bulges, or--in many cases I suspect--have not even checked.

Dutch061

As I ponder the corrosion issue and look at the photos again, a strange thought occurred to me. It appears that the majority of the corrosion issues are between the rubber hoses and the outside of the hose connections on the convectors.

What if the lubricant (I suspect they were lubed) that was used to install the hoses is the root cause? If it is galvanic action caused by poor grounds, a ground feedback, and/or low Ph glycol, wouldn't the corrosion be eating the convectors from the inside out? Or is it just the "pooling" of coolant that isn't able to circulate that is trapped between the hose and the convectors? 

Too much time on my hands......

Brad

Denny16

I think the latter is probably the issue with the older Century TF fluid previously used.
 Cheers 

fstop32

@Dutch061, while I'll have to wait for better minds than mine to research the galvanic action I did come across something that might support the "pooling" theory.  When I ordered 2 new convectors from Alde I noticed crimp depressions on one end of each convector.  They appeared to be tooling marks where the tube was being clamped and cut, leaving one cut end undamaged but the adjacent end dimpled by the clamping process.  When I went back and looked at the six convectors removed from my T@b the worst corrosion at the convector ends always occurred at the end with the tooling marks.  You can see my photos on page 13 of this thread.  These dimples would make it much easier for pooling to occur especially if the dimpled end has the glycol flow running toward it.  While the pooling might not be the only problem it would seem to at least exacerbate the issue.
FWIW, before installing the new convectors I cut the dimpled end of the tube off on my chop saw.

Freespirit

@fstop32, I agree with your “pooling theory “ as a possible cause for the corrosion. There are numerous members smarter than myself when it comes other theory about the corrosion, and it may be a combination of all of them. 

I rebuilt my entire Alde system(not the boiler) and found the majority of corrosion around the tooled ends. Like you, all 4 of the new convectors I ordered from Truma had tool marks on one end of the convectors. I also cut about an 1/8 of an inch off the tooled end of the new convectors. As another percussion I doubled clamped any hose connecting to an aluminum part.   I saw no corrosion around connections where the rubber hose connected directly to the Alde, 

fstop32

@Freespirit, your observations were the same as mine, I had no issues at the boiler s well.  I too double clamped plus I added a layer of 1" heat shrink to the ends of the convectors.  In a couple of years when I have to change my glycol out again I'll pull a hose off one convector and see how things look and update my observations and theories 

BrianZ

I just wanted to say thanks to @Dutch061 for the illustrated guide you posted on the previous page to help tabbers apply Airstream's grounding mods for the Alde. 

Also, Brad, in reference to your last comments above in reference to the cause(s) of the corrosion on convector stubs, I've commented a number of times about the possibility that the Loctite sealant previously used to seal the hoses against the pipes could have been a major contributor to this crevice type corrosion due to local pH changes.  That 5923 sealant is a paste made from talc, minerals & rubbing alcohol.  The very fine solid ingredients could, I believe, be a setup for this after the solvent dries out under high temps.  It was previously listed in the Alde catalog ..

Dutch061

Brian,

You and the rest are most welcome, I felt that the grounds and the Airstream bulletin were important enough to create something that transferred to TAB's as clearly as possible.

Thank you for sharing the information regarding the Loctite Compound. If this was used "widespread as the recommended sealer by Alde" and is the potential root cause, Alde/Truma should be picking up the cost for this in my opinion.

However, there is one remaining question in regard to this Loctite Sealing compound and that would be "if it was used across the board, why wouldn't every TAB be affected"? It seems to me based on all of the photos that the corrosion is not caused by the PH level or corrosion inhibitor package being depleted in the Glycol but rather something else like the "Loctite Sealing compound" or some other substance used during assembly since it is corroding from the "outside in rather than the inside out".

After looking at the Technical Data Sheet for Loctite 5923, it is very doubtful this I the root cause. I say that because this is rated for use in aircraft. I have attached that sheet to this response. 

In other reading, 5923 is rated effective for use when in contact with water, ethylene glycol, gasoline, motor oil, transmission fluid and sea water.

Brad