Corrosion of Alde Convectors

Denny16

gulfarea said:

@Denny16 For 31 years I owned a Diesel garage. Worked on all kinds of gas and diesel radiators and heaters. If we had this problem and had to change antifreeze every year in our cars, I say something is wrong! Art

Art, 31 years ago, diesel antifreeze was changed every 12 months.  My 1983 diesel tractor manual stated to change antifreeze inmthe cooling system every 12 months.  My marine Diesel engine antifreeze in the cooling heat exchanger was a 12 month change cycle, one I missed and didn’t do for 2 years, and lost the manifold head (which was aluminum) on the heat exchanger.  The Alde recommended change cycle is two years, not every year, and is because of the anti scaling and corrosion additives, not the actual glycol, limited service life.

Today’s newer automotive antifreeze has a longer service life, typically 5 or 10 years.  But the Alde glycol is not being used in a internal combustion engine cooling system, rather a heating heat exchanger system, being circulated through aluminum convectors.  The Alde glycol, could more accurately referred to as a heat exchange transfer fluid, and is a completely different formulation than the antifreeze formulas used in an internal combustion engine.   

Cheers

ScottG

Four owners thus far have reported bulges in their convector loops. All were 2014/2015 models. Two had never had the glycol changed, but two had changed it in accordance with (or close to) the recommended interval.

While the worst corrosion (reported by @fstop32) was evident in a heavily used system with six-year old glycol, these examples suggest that changing the glycol regularly may not be the only factor contributing to the deposits and their associated corrosion. 

Repeatedly concluding that this could be prevented by keeping up with glycol changes is unfortunately not supported by the current evidence.

Hopefully as owners get their T@Bs out for the season, we'll get more reports (good or bad) on this issue.

ScottG

Regarding reconnecting of the hoses, I do agree that double-clamping or the use of sealer may help to mitigate the issue by preventing glycol infiltration between the hoses and the aluminum fittings.

When I disassembled my system, I noted the hoses--once unclamped--slid easily on and off the fittings. While this facilitated disassembly and reassembly (Phew!) I suspect it also contributes to the problem.

I find it interesting that Alde offers a sealant among materials. Also that they have abruptly switched to a different recommended brand of glycol. Makes me wonder what they know that we don't.

To be clear, I'm not drawing conclusions or assigning blame, rather just observing and asking questions. 

ChanW

@ScottG, I don't remember if I actually saw an Alde instruction that the sealant should be used at the hose/ convector connections, or if I'm simply assuming so from their catalog description.

The sealant is also sticky, I believe, which suggests to me that your 'easily-removed hoses' didn't have it applied.

ChanW

@fstop32, note in the  Loctite 5923 specs that you can soften it (to remove it) it by soaking it in alcohol...

Makes me wonder if it wouldn't be very good for sealing against glycol!

(Also note its 24-hour cure time)

fstop32

Thanks @ChanW and @tybladesmith!  My T@b will be sporting one of those as fast as I can get my hands on one!

Tampakayaker

@ChanW Using the screw on the screen seems a lot easier than the included springs.  Comments on Amazon make it sound like the springs are a pain to install.

tybladesmith

FYI,  I did not find Loctite 5923 used on my 2018 320S. Only connection taken apart was at the down stream side of the auto bleed valve after the outlet of the Alde, and no bulging of hose connections found.

fstop32

Woohoo!  At the next rally I attend I think I'll carry a sign that says "Just Say No To Bulges"!

Denny16

Scott, so far we,only have four examples, two,without changing the glycol and two thst did. We do not have enough data to to draw any definite conclusions, one way or the other.  But keeping the glycol changed at regular intervals is the recommended practice, and many  older RVs with the Alde are not reporting any issues.  

Cheers

ScottG

Does anyone know what other U.S. manufacturers use the Alde in their RVs/TTs? I'm aware of Airstream, but others?

(European Aldes appear to be more prevalent, but those use a different glycol concoction so would not be a relevant comparison.)

Denny16

The Nest line of trailers has the Alde, along with Roadtrek Vans, and some other highness Class A coaches use the Alde system.  It is more popular in the UK and European markets, as it has been distributed there longer.  

Cheers

ScottG

Just found this interesting tidbit for the T@B history files. Looks like Roadtrek was the first to adopt the Alde in 2013. Given that @ChanW's 2014 has an Alde, nuCamp (then LG/PV) wasn't following too far behind.

Airstream didn't incorporate the Alde until its 2017 models, so those units haven't been in the field as long as the original LG/PV T@Bs.

Denny16

Interesting info Scott.  Airstream did introduce the Alde in its UK Airstream units in 2013-2014, so it seems the UK Airstreams had the Alde befor thenUS market trailer’s did, and then it is only in the higher end models here (International model), where all UK Airstreams have the Alde, according to Andrew Ditton, an Airstream UK Ambassador.
cheers

fstop32

While waiting to source parts for my "situation" I thought I'd do some mock ups for some changes I have planned.  Originally the two long rear convectors were mounted one on top of the other and screwed to the back side of the headboard.  I found getting to them to work was a bit of a pain so I'm planning on mounting the new convectors to a new crossmember I'm installing.  That will mean I can pull the headboard panel out with little effort and I'll have easier access to mount hoses and convectors.  The crossmember will be attached to the new rear bench trusses I built (the outside piece of which extends past the headboard.  I found my old convectors were decent stand ins for the real thing.  I'll be adding a 90 deg elbow to connect to the reservoir since I found the old one had a kink in it from the tight bend.  That does add another joint to swell on me but I'm confident this problem will NEVER occur again! 
And I'm thinking of routing out a "sight window" in the headboard where I can see the glycol level in the tank more easily.
Let me know if anyone sees any problems with this arrangement... 

fstop32

This forum must be running an "algorithm for idiots"    I speak of myself, thanks to the masked post corrector!

Denny16

Looking real good, I like your mods, very clean looking...

While you are in there, might as well add some wire ties to cable up those loose wires and some stick down wire toe downs to hold them in place against the back.
cheers.

Bayliss

@fstop32, the only question I have regarding moving the one convector forward is whether there will still be a horizontal vent along the back headboard area so that the heat can rise from both convectors and into the cabin?  Your description may answer my question, but you indicate that the outside crossmember will extend past the headboard.  I'm not sure if that is behind, or in front of, the headboard.  It could be that I just don't fully understand exactly how it will be configured once completed.

P.S.  I went back and re-read your April 4th description of what you are doing.  It sounds like there will be an airflow opening to allow for the change in convector location, but I'm still not fully picturing how it will all look when done, so just curious.

ScottG

fstop32 said:

This forum must be running an "algorithm for idiots"    I speak of myself, thanks to the masked post corrector!

We run a quality organization here, @fstop32 --deletions, edits, and relocations on request!  ;-)

I don't see any issues with your rearrangement. I suppose it's possible you might get a little less airflow over the rear convector (since the intake is from the front) but I doubt it will make any practical difference. Speaking from experience, it sure will make those connections easier to access for inspection and maintenance.

fstop32

@Bayliss, essentially I'm rolling the 2 rear convectors which were on top of each other to a side by side position.  It seemed to me some of the air rising behind the headboard had space to come up behind the convectors instead of through them.  Mounted side by side I think more of the air will actually pass through the convectors.  If you look in the first pic above you'll see a notch cut into the driver side bench support.  That notch is where the headboard will sit with the reservoir partially attached to the back side of the headboard like normal.  The 1x4 now between the two convectors is the new crossmember and the convectors will attach to it instead of the headboard.  There is enough space in that area for the air flow to rise like it normally would.
1st pic below is the new passenger side bench support (the pointy end will get some work once I get my hands on new convectors and hose).
When I rebuilt the middle bench support (pics 2 & 3) I turned it into a boxed beam.  I'll cut a port in the bench face panel where cabin air can enter the "duct" and there will be a small switchable fan amidships inside that beam pointing down at 45 deg to push air toward the rear and down.  To @ScottG observation, on that beam I've raised the sides of the rear portion so some air in the beam will be spread out side to side.  Also, the stubby rear most end has a sloped baffle inside so the air has to go down and under the headboard, not straight into the convector.  I've left all the T@b designed air flow as is so air can get to the convectors as it normally does.  I mounted conduit through the beam to allow the propane supply hose and wiring to be passed through.  There will also be a port door on the side of the beam for access to the fan and its position and angle.  Pic 4 shows the mid beam and a mock up headboard piece.

   
   


The driver side bench support beam will have an inside ported panel like the passenger side but that will be put in after running new hoses and cleaning up all the wiring.  @Bayliss, I climbed in there yesterday to cleanup that mess of wiring you saw and decided to wait until I had the hoses run and secured before routing the wiring.  In the last pic the area directly behind the convectors will get some insulation and the reflective foam panel original to that location which will help funnel the air through the convectors as it rises.
Of course all my "thinking" what the air flow will do and the reality of what it "will do" is open to conjecture 8^D   I've always wanted a smoke machine so I could create a slo-mo wind tunnel to confirm/deny my theoretical ideas 

   

@ScottG ...this might be the progression of the story that might not have all that much to do with "corrosion"...

Bayliss

@fstop32, thank you for the additional explanation and photos.  Very helpful.  Looks like quite a project for you.  I am following to see how it all turns out.

fstop32

It all started with just a little bulge   I do enjoy the reno projects though I don't think I would have been this deep into "The Escape Pod" had I not been pushed there...ok, I probably would but not this soon 

ScottG

@fstop32, the ends of the two convectors I can see in one of your photos still look pretty intact. The one you showed early in this discussion was certainly toast, but how many other actually had corrosion that has progressed to the inside of the pipe?

fstop32

@ScottG Three of the six convectors had holes eaten through one end.  It was sort of weird that one end of a convector was toast but the other end was in good enough shape that I would/could reuse it, and don't you know it is one of the 8" ones!
I send an email to Chantal @ trumacorp yesterday so I'm waiting to hear back on what they can do and how much it will cost me.  I also sent her a host of pics.  If they can help I guess I'll be making a run to Elkhart IN in the near future.

ScottG

Ok, @fstop32, next question... 

How were the six convectors arranged? I only have four--two long ones taking up most of the space behind the bed, and two short ones under the passenger bench.

fstop32

I have (had) two more under the driver bench, each only 8" long.  The two under my passenger bench are each about 14" long. I had picked up in other posts that some T@b's did not have convectors on both sides.
I do wonder why the short ones under the driver bench were pulled...too much compartment heat for the electrical system?

ScottG

Interesting. To date only @ChanW's 2014 is the only one I am aware of with the driver's side convectors. They must have made that change (among others) in the middle of the 2015 model run.

fstop32

@ScottG, I meant to mention I'm going to replace the driver side convectors with an "in built" version that is recessed into the cabin panel which picks up cool air directly off the floor and lets it rise through the convector and then passes it out back into the cabin.  I thought that would help keep that compartment from being as warm.

db_cooper

I've decided to tackle the corrosion head on, so will be fully draining the system and removing/cleaning connections.  I think I've caught it early enough like @ScottG to reuse everything.  

I'm stealing an idea from Mark Turney on the T@b Facebook page and putting in a low point drain under the passenger seat through the floor using a copper T.   My plan is to clamp both sides where I'll be cutting the hose, install the T, then drain and clean the connectors.  This corrosion has got me planning to do full glycol exchanges rather than my yearly add a gallon of fresh, since that did not seem to work.  I may run the Alde less in the winter when parked at home as well to prolong it's lifespan.  I had thought using it would be better than sitting idle,  like most machines, but in this case it seems better to not use it except when necessary.

fstop32

@db_cooper, I hope Mark didn't patent that idea because that's the way I'm going too once I put mine back together.  I haven't fully decided to poke another hole in the floor or just plumb in a low-point ball valve in the passenger bench compartment to which I can hook a drain line and let it snake out the cab door in the front and out the camper door to a bucket.
Like @ScottG, if you can catch it early it's much easier and cheaper than the route I've had to take.  I'll be looking for how that goes!