Corrosion of Alde Convectors

At least I've found all the glycol hoses have a little extra length, so I can take some pressure off the fittings.  That was not the case with the propane line to the fridge recall we had.  That sucker was tight.

I have a 2015 S-Max. We have rarely used the Alde system for heat (and probably electric then), and never for hot water. As a result, I have not worried about changing out the working fluid (40-50% ethylene glycol). I've been thinking about it though, and came across this thread. Now I'm more worried. I just took this photo of the rear convector connections on the reservoir side. To me, the slight bulge does not appear unusual. Am I mistaken? When I get a chance, I'm surely going to change out the fluid, but it's likely to be couple of months. 

@glesieutre, I'd say the good thing is that bulge looks very minor compared to the ones I had, but you don't want to ignore them.  I'd suggest checking those out when you change the fluid.

Didn't we learn that the boiler innards are stainless steel, so less likely to have this problem?

db_cooper said:

............
I'm thinking that the boiler is probably compromised to some extent, so switching to the new fluid is not worth the trouble.  

Longer term, I may replace the entire system, as long as it's cheaper than a new trailer, and of course use the new fluid.

@ScottG
I'm done with my attempted repairs of the connections and have put everything back together.  I replaced most of the clips with screw type hose clamps, especially in the hard to reach places.  I also doubled up with one at the end of the hose and another as close to the end of the connection as possible to keep the fluid from pooling between hose and outside of connections.   I don't have any leaks and think 2 hose clamps is better than 1 clip.  All of the corrosion I found started on the outside of the tubes, so I'm hopeful the boiler unit is OK.

I flushed one round of distilled water through the system, and got just shy of 2 gallons into it. When drained I still had some yellow glycol in the mix,  there must be a bit in the boiler that doesn't drain, but not enough to worry about.  I then got just shy of 2 gallons of Century fluid into it.  

I'll be watching for hose bulges in the future, but until I have a leak or bulge those hoses are staying put. I'll do the full flush using this method every 2 yrs, and see how long she lasts.

On the broken tank connections,  the JB Weld Plastic bond seemed to work great.  You can't be gentle putting back together and it held together fine.  I had to cut a couple inches off of one of the hoses to keep from putting too much pressure on the fitting.  Part of the reason it broke was because of how much side pressure was put on the fitting when they mounted the tank. So much the tank deformed a bit.  I clamped above and below the break, so even if it fails it shouldn't leak.

My best recommendation from this is to clamp your hoses to keep that fluid out, but that is a bit of a job in itself, so I doubt most will want to bother.

Does anyone know if there have been any documented problems with corrosion using the Century fluid that has been  changed every two years per the maintenance schedule?
I have a 2021 T@B 400 built in March 2020 that I'm trying to decide how to proceed with the Alde maintenance.
Should I bite the bullet now and make the expensive change to the Rho-mar Water or just flush and change the much less expensive Century fluid at least every two years (or more frequently)?
Is there any data that suggests changing the Century fluid more often, like every year, would prevent corrosion issues? 

I drained my fluid today and pulled one of the curved rubber hoses that connects one of the upper and lower heat exchangers. The exchanger ends looked brand new. Not a sign of corrosion. For the record. The fluid is original in my 2017 CS-S. We have about 20k miles on the t@b at this point. We have not used the alde for cabin heat very much, but do heat domestic water every trip.

Chris, you are absolutely on the money. I am the original owner so I know what has been in this system. I will go with the Century fluid for the next interval. Hopefully, Alde and NuCamp will have there arms around this issue soon.

Denny16 said:

Finding a product that increases the corrosion protection is reason enough, if yiur strive to improve your product.  Does not mean or imply the previous system didn’t work well.
cheers

In the Quality World, we called that “continuous improvement”.

Well the Century fluid works, and protected your Alde system well beyond it shelf life. 

It seems the TaBs that have the worst corrosion issues, are the ones used infrequently, and most did not keep up the glycol change every two years.  But @Dalehelman posted in a different discussion, his frequently used Alde, a 2015 Tab with its original Century TF-1 glycol has no corrosion or scaling issue.