Corrosion of Alde Convectors

Tampakayaker

I guess if the Alde craps out totally, you don't boondock, and use showers at the campgrounds, you could heat the camper with those electric heaters.

gulfarea

Unless SS would be out of this world expensive I would buy them rather than go threw all this mess. Not to many convectors in a 320. Art

fstop32

There are worse scenarios...it's called backpacking! @BridgerSunset you're my new BFF, that was way better than my WAG!  Maybe that's why the Alde catalog lists the Loctite 5923...
I'm with you @db_cooper, we work hard to customize these things to fit us so as long as I can find parts I'll keep this one rolling (he says as he waits to hear what hoops he'll have to jump through for parts...).

ScottG

gulfarea said:

Unless SS would be out of this world expensive I would buy them rather than go threw all this mess. Not to many convectors in a 320. Art

I'm no metals chemist, but the graphic I posted on the previous page of this discussion suggests that SS is not a good mate for aluminum, either. As the cathode, the stainless convectors would be well protected from corrosion, but the combination could promote corrosion in the anodic aluminum boiler core.

Given my preliminary gander at prices for parts in the U.K., I'd rather replace my convectors every few years than have to replace my boiler body once.  ;-) 

ScottG

BridgerSunset said:
...
Not sure if a high pH fluid after the corrosion inhibitor is gone is good or bad  - anyone know??  If it's bad, I'd expect corrosion throughout the entire system.
...

Great info and assessment regarding crevice corrosion, @BridgerSunset

To help answer your question regarding pH, @tybladesmith posted this over in the Rhomar glycol discussion. I knew there was an optimum range of pH but didn't realize how rapidly the corrosion protection falls off once you get outside that range. I suspect the Century fluid has a similar profile--maybe shifted a bit to the right as I've generally heard 9.5 tossed out as the optimum. Regardless, those of us who have tested our glycol have found it to still have an acceptable pH.

db_cooper

So the repairs have begun! 😁

For the rear convectors and one of the short connection pieces that have pinholes, I have applied regular JB Weld to the outside.  I will sand smooth on the outside when dry. 

For all the hose connections I will wrap the aluminum with silicon rescue tape and use the original clamp and extra hose clamp.  My hope is to prevent glycol from pooling on the aluminum underneath the hose. The pictures are of the short convectors reinstalled.

I'm also flipping the convectors upside down and putting the better ends where the worse corrosion appeared.

My further plan is to never look again until I have a leak! And to do a full fluid replacement every 2 years and use it as long as possible.  I will not use it plugged in at the house anymore, but use a space heater.

The hoses will slide on over the rescue tape, but the clamps are tough to get on. I was just able to get them on the outside edge, which is where I want them to prevent glycol intrusion.

Y'all are free to armchair quarterback this ridiculous repair, cause I don't care anymore. 😁 Are you not entertained? 😜

(Edited to reduce photo size.  Moderator)

ScottG

No criticism here, @db_cooper. Looks like simple and reasonable measures to me. Either way, I can't see where they will cause any further harm.

SLAM

   Been following this thread from the start as I to have to change out my alde fluid. My 2018  320s Outback purchased in the spring of 2017 has never had a change. Was going to do it last spring but life got in the way.
   Did a quick check for hose bulges, found one on the passenger side convector, couldn't see the bulge, but could feel it. Need to do a check of the rear convectors but need to move a bunch of stuff.
   Been researching  RO vs distilled water, and it seems RO units put some dissolved solids (hardness) back in the water to give it taste and you don't  want any dissolved solids in your alde. The distilled water from the store is not lab grade, but I will be using the store stuff for my flush.
   I will be using the permatex aviation liquid gasket which is the loctite equivalent on my connections and using double gear clamps.

RCB

As to clean water for the flush - perhaps water from your dehumidifier.
Again about clamps - on my last boat with a large diesel, the clamps on the cooling hoses were a very robust bolt type. So the comment about expansion of the hose with the factory clamps may well contribute to coolant seeping under the clamped portion of the hose.

trimtab

We have a 2020 320s Boondock...the question of the day is: is it fated that all Alde heater systems will have this problem? even though the glycol is changed every two to three years?
My dealer today said I do not need to change to the new water based glycol..

Denny16

The previous Century glycol was also water based, both are premixed with distilled water.  If you are doing a full glycol change, might as well give it a flush and replace with the new recommended glycol.  I still have an unopened gallon of the previous nüCamp supplied glycol left, I got last July, when we had our glycol changed out.  Next time round, I will switch to the new Rhomar glycol solution.   If anyone needs the gallon I have left over, PM me.
cheers

db_cooper

My saga continues tonight.  Barely moved the hoses attached to glycol tank, and both snapped off easily.  So tomorrow I will attempt plastic welding.   The tanks apparently get very brittle from the hot glycol cycling through.  I successfully welded a plastic mountaineering shovel this year and have the acrylic welding stuff left over.  It's worth a shot before ordering a new tank.

So much for fillin er up tomorrow...

Bayliss

Total bummer for you, @db_cooper.  Not a good way to end your day.

fstop32

Again, I feel your pain @db_cooper.  The close quarters and the fact the rear convectors were mounted to the headboard gave me reason to design a different way to mount the new ones where the headboard can be removed/replaced w/o involving the hoses and convectors.  I wasn't saving my hoses back there so I cut them so I didn't put any pressure on my tank, what happened to you though gives me pause about using the old one going forward.  What a mess that would be if it snapped in the middle of a cold night boondocking!

db_cooper

I can't stress how easy they broke, the second snapped while I was unscrewing the tank and there was no pressure applied. There's a metal sleeve inside the outlet and it snapped right above it. I think the spring clamps are too strong for it, so will replace with screw type above and below the break.

I was able to fish the broken pieces out of the hose, but there is no way I could have removed the hoses from the tank without breaking the tank if I'd wanted to. Word of caution.

ScottG

Sorry to hear the latest development, @db_cooper. 

Years ago there were a few reports of leaks from cracks that had formed where the hoses attached to the expansion tank. That has stuck in the back of my mind and was one of the reasons I wanted a glycol exchange method that did not involve detaching those hoses. Your unfortunate experience is a good reminder and cautionary tale.

When I inspected and cleaned my system, I did not remove those hoses as I assumed the plastic connections would not be affected by the deposits or corrosion. Since you took the plunge, can you confirm if that was indeed the case?

@fstop32, I could probably ask the same question of you, since you fully dismantled your system as well.

ScottG

trimtab said:

We have a 2020 320s Boondock...the question of the day is: is it fated that all Alde heater systems will have this problem? even though the glycol is changed every two to three years?
My dealer today said I do not need to change to the new water based glycol..

Good question, @trimtab, I'm not sure anyone (even Alde) knows the answer.

Not many owners have older T@Bs have weighed in, so I don't know how many have inspected their convectors and found--or nor found--the tell-tale bulges. Of the few I have heard from, most--but not all--report some degree of bulging.

The amount of use the system gets seems to be a major factor. Not changing the glycol as recommended may be a factor, but that is less consistent in our thus far limited sample size.

Whether changing to the new Rhomar glycol will prevent this on newer T@Bs is also not yet clear.

fstop32

@ScottG, all I found in the reservoir was that light coating of white powdery looking stuff.  I didn't encounter the brittle plastic but since I was not trying to save the hoses I just cut them to make it easier to get the individual part out and therefore did not have to apply any pressure to those fittings.  I was probably going to reuse the reservoir but after @db_cooper's experience I'm really hesitant to not replace it.

db_cooper

@ScottG ,  there were no deposits at the hose connection of the tank.   Based on how easily they broke off,  I'm pretty sure they had developed cracks already.   I think the hose clips they used were position right at that point where the metal sleeve ends, so there was too much pressure on the unsupported plastic.  

I'll be attempting the repair in a few hours, I can't tell for sure what type of plastic the tank is,  I'm hoping it's ABS,  so my acrylic solvent repair will work.   

Sharon_is_SAM

@ScottG - got into our TaB yesterday.  No hose bulging.  We changed the glycol in 2019 at the suggested interval.  The glycol loop viewable from the end of bench door at the entry looked fine.  Without disassembling the rear panel, I could only view the rear convector/hose partially as it runs to the Alde.  All is well🤞

Denny16

Perhaps the plastic used for the reservoir tank got brittle over time from the Alde glycol heat?  Prolonged exposure to heat will make some plastic material brittle.
cheers

RCB

Our 2019 - 400, built Jan 2019 shows no hose bulges or leaking glycol at least at the two front convectors. I have yet to change the glycol - it is now on the list.
Another thought, might air in the system promote the formation of the green crystals evident in some photos ?

db_cooper

@Denny16 , that's what it looks like to me,  the tank is pretty yellowed, and I think it was heat related deterioration.

@RCB ,  I rarely had any gurgling,  but I'm sure there's air mixing in the expansion tank at times and going through the pipes.  I'm hoping that wrapping the connectors with silicone tape and double clamping will slow the corrosion down so we get a few more years out of them.

As for the tank,  acrylic welding solvent did not work at all, so it is not polycarbonate.   Plan B seems to have promise,  I had some JB Weld Plastic Bond laying around for another project, and it appears to have cured quite solid.  I'll know for sure when I go try to clamp the hose on it.   I plan to double clamp the tank fittings as well, and put one above the break where there is no metal sleeve, but carefully tighten so as not to break anything.

N7SHG_Ham

The tanks cracking at the inlet and outlet is fairly common, has happened enough that it isn't a unique issue. Cause, might be a combination of heat, stress, vibrations. Patrick at TWD had that issue once and I think had a video on it.

No idea if Alde has modified the design over the years or if we can all expect that at some point?

Denny16

It’s a good thing to keep an eye out as it gets older..
cheers

Tabaz

The inlet on my plastic tank cracked after one year of ownership.  I read somewhere it was caused by the lack of a 90 degree bend in the hose leading up to the tank.  Replaced the tank and installed a wider bend in the hose.  No problems in the last four years.

trimtab

Ok, really uninformed, so where are the convectors located ?on a 2020 320..I am trying to believe that I don't have or never will have any corrosion problems....

Denny16

In the back behind the head board for the bunk and under the pax side bench.  Some 320s have one on the drivers side bench where the Alde boiler is, towards the front, some do not.
cheers

trimtab

Thanks Denny16...I thought that might be the case...much appreciated and I have now been edgeacated!

fstop32

@Tabaz , while I haven't had a tank plastic problem yet I did notice when I pulled mine apart that the hose going from rear convector to tank was "kinked" which besides restricting flow somewhat it was also applying sideways pressure against the connection neck of the tank.  I'm planning on my reinstall having the appropriate bend and mounting/support hardware to correct those issues.