Corrosion of Alde Convectors

tybladesmith · April 2021

@fstop32, I think you are on to something. If one added the Dual Drain bottom fill hose in the baggage compartment on the return side of that convector that would be the other low point in the system. Two holes would need to be drilled through the floor avoiding aluminum floor/frame crossmembers. One could drain and flush from there. This is behind the coroplast bottom so it is accessible.

Sharon_is_SAM · April 2021

@fstop32 - IIRC we were quoted a pH of 9.5 - 10.5 by a former Alde rep.

fstop32 · April 2021

@tybladesmith, I'm guessing the idea here is to clamp between the drains, then pump in distilled water (in the direction where it won't incur the wrath of a check valve) while letting it drain out of the 2nd drain, then pump fresh glycol where you were pumping the water until you see the fresh stuff starting to drain out?
How would one define a "bottom fill system"? Is that a system different than what I have in my 2015 320S or are we just saying we'd fill from the bottom?

Thoughts on making the same thing with 2 single drain T's with a ball valve between so you don't have to potentially weaken the hose by repeated clamping?
Any thoughts on turning the T's on their side and running it out at floor level through a ball valve and then a water hose type connection...other than the aesthetics of having two new pimples showing on the side of my camper?

I'd love to come up with some other way of filling the system that doesn't demand it to be done at the reservoir, so a bottom fill idea sounds great to me. My thought about coming out the side would just be the easier position than on my back with short buckets. Two very short hoses catch the draining fluid and facilitate a connection to pump into the system.

@Sharon_is_SAM, I was hoping the pH might help identify what happened so I could actually feel better about what will happen when I put it all together and get back to traveling. I suppose a heavily use system with no fluid replacement for 5 years could have just lost some of its corrosion resistance.

I'm enjoying all the input! Thanks!

Sharon_is_SAM · April 2021

@fstop32 - I think your Alde is an unfortunate example of depleted corrosion resistance. Now we know!

ScottG · April 2021

tybladesmith said:

@ScottG, Alde bottom fill dual drain hose for bottom fill systems. ? Add this inline at a low point, clamp in-between and then drain/flush with distilled water before refilling with fresh glycol. Maybe even replacing the existing drain with a dual drain and fill under slight pressure to auto purge the air into the reservoir after the isolation clamp is removed using the onboard circulation pump. What do you think?

@tybladesmith, I think this would work--it's essentially the same idea I was toying with originally. At the time, I don't think the dual drain component was available, but one could do much the same thing with a second drain (or some other type of appropriate T-fitting) installed adjacent to the existing drain.

@fstop32, your description was exactly how I envisioned the system working. With separate fittings, the inlet side could even be inside the camper--that would eliminate the need for another hole in the floor (but would also increase the mess factor in the event of a spill). I contemplated various arrangements involving T-fittings, ball valves, and even T-port multi-function ball valves, but trying to find fittings that were a) the right size, b) compatible material, and c) economical was proving more complicated than I had hoped.

Eventually I decided to hitch my wagon to @gregndeb's adapters--these allow you to do essentially the same thing from the reservoir without the need to install additional components or dismantle any part of the system. I'll be giving these a go with a hand pump in the next few weeks and will report back on my success (or lack thereof).

Of course, the adapters don't solve the problem of needing to access the reservoir, but in a 2015 there seems to be plenty of room to get them into the top of the tank. This may be a bit trickier in newer 320s with the enclosed rear sides, or the newest 320s where the reservoir is behind the toilet.

fstop32 · April 2021

@ScottG, definitely let me know how the adapters work out for you, and what hand pump you go with.
I doubt I'll have parts in hand to start re-plumbing any time soon so whatever you experience will be helpful for what I'll be doing. I guess I've got the "benefit" of having to remove so much stuff that it's much easier to envision changing a lot of things while I'm in there which is why I'm entertaining so many different ideas.

I'm currently replacing almost all the wood compartment plywood and the 2x4's and building new framing in sort of a truss fashion. The new center member will be 2 pieces of plywood separated by probably 4" of space between. I'm going to make that a duct that can feed cabin air from the cabin floor directly to the back convector area unimpeded by whatever is packed in those compartments. Also planning on a switchable fan to pull air through and to the back to help kick start the air circulation and warming. (humm, all that stuff probably needs to go in a different thread...).

ScottG · April 2021

Well, golly. Inspired by this discussion I went out to take a closer look at my own 2015 yesterday and--yep, you guessed it--found several bulges in the glycol hoses where they connect to aluminum convectors or other fittings. The bulges look a little smaller than @fstop32's. Although I can't tell for certain without pulling off the hoses, I have no reason to believe they are not from the same sort of corrosion detailed here.

In contrast to fstop32's Alde, mine has gotten very little use. I've run the cabin heat probably a half-dozen times over six seasons, and only fire up hot water for a short period once or twice a day when camping. The glycol looks good and tests within the proper pH range.

But--to all of you shaking your head and tsk-tsk-tsking at me right now--you are correct that it is the original glycol. Partly from ignorance and partly from calculated risk, I've put off changing it well beyond the recommended interval and if that is at the root of the issue I accept full responsibility. However, given the apparent condition of the glycol, the minimal use of the system, and the generally conservative nature of maintenance recommendations, I'm not completely convinced that my negligence is solely to blame.

At this point I have no intention of dismantling the system and risking further damage unless a malfunction or leak arises. I will be changing the glycol soon and keeping a close eye on things over the coming season. Alde or not, the T@B is still a whole lot nicer than a tent! ;-)

I should emphasize that I would never have noticed those bulges had I not been looking for them. I would suggest owners of older T@Bs inspect your own units (whether you have been changing the glycol or not). Keep in mind the bulges are small and may be hard to see depending on where they are located--I found it was often easier to feel them than to see them.

Good luck, and please report back what you find!

Sharon_is_SAM · April 2021

@ScottG - are the hoses bulging due to a build up corrosion or is it due to something else? How long should we expect the hoses to last under typical use? Anybody out there with bulging hoses who kept up with the required glycol exchanges?

ScottG · April 2021

Good questions, @Sharon_is_SAM --that's why I'd be interested in hearing if anyone else is seeing (or not seeing) this, and under what circumstance.

Given the location and firmness of the bulges--and that it is not a pressurized system--it certainly suggests something is building up underneath the hoses at those connection points. Given @fstop32's photos, I think it's a pretty good guess (but still only a guess) what that something is... :-/

fstop32 · April 2021

Here are a couple of additional photos that show how the corrosion was building up and forcing the bulge in the hose, that's also why the bulges feel hard. The first one that started leaking was due to the corrosion "growing" between the pipe and the hose which eventually caused the hose to split as it was expanding against the edge of the hose clamp. Except for the bulging my hoses seem to be in good shape otherwise...i.e. I don't think it's a problem with the hose failing.

I'd love to hear that others with 5+ year old T@b's that have had their glycol changed on a regular basis are "bulge free"! That would help me feel like it's a problem with the corrosion resistance breaking down over time/use due to failure to replace. It doesn't seem that pH testing will show this problem, mine tested at a "10" so nothing crazy there. But I hate hunches, I'd love to figure out somehow exactly what caused this problem. Sorry about your bulges @ScottG, I feel your pain!

P.S. I cut through the center of the bulge in the first pic with the result shown in the second pic.

Image: https://us.v-cdn.net/5021717/uploads/editor/sv/zh9qgrgaaey8.jpg

Image: https://us.v-cdn.net/5021717/uploads/editor/aj/jiogupskcu85.jpg

Denny16 · April 2021

That is the same type of corrosion I had from the glycol failure on my boat heat exchanger, white powder/crystal looking stuff.
cheers

ChanW · April 2021

@Denny16, I don't understand "ok'd glycol failure".
Do you mean it tested ok?

ScottG · April 2021

Thanks for additional pics and info, @fstop32. A couple more questions...

Could you tell how far into the convector the corrosion extends. I'm curious if this is evenly distributed or if it seems to occurs around the connections with the hoses
Per your previous comments, were you planning to open up the boiler and inspect it's innards as well? (Assuming that is even possible...). Convectors are one thing to replace, the entire unit is quite another.

Also, any further progress in finding a source of parts? It appears there are several places in the U.K that sell Alde components--at least one even has a version of their site set up for U.S sales. The convectors themselves are not that expensive, but the shipping is pretty steep.

N7SHG_Ham · April 2021

This could be some sort of electrolysis and not necessarily related to the fluid degrading? Hopefully Alde is responding and will take a look at parts as well as sample of the fluid. If this is due to not following recommend change intervals, it should serve as a wake up call to everyone who owns an Alde system. If it is something else, that means we all will have an expensive repair in the future despite best efforts to change fluid. I sure hope Alde is taking this seriously!

Denny16 · April 2021

@ChanW. Yes, the glycol tested ok, but was almost two years old in the system.
Electrolysis requires two dissimilar metas to either be in contact or in a conducive solution (like salt water) so sone metal gives up its electrons to the other metal. This is more like corrosion, as aluminum oxide is a white substance, which can build up per the photos posted here.
Cheers

fstop32 · April 2021

Here comes some more info & pics...I'll break it up a bit so it's not in one big thread blob. I grabbed the elbow just off the upper rear convector with the bleeder valve and disassembled it. The upper end of that Al union (see pic) went into the elbow and the lower (crustier end) went into the hose coming up from the upper passenger side convector. For what it's worth the glycol flow is going from the hose into the union then into the elbow then through the upper convector and around to the driver side convectors. So in this case (and I think the others followed suit) the worse corrosion is found on the input side of the junction or convector, maybe pushed somewhat by the flow???
The 2nd pic is just a better shot of the inside of the union.

@ScottG, to your question about how far the corrosion went into the convector...the inside of the convector pipes look just like the union in this pic. It looks like a white powder layer but it does not rub off easily. From everything I've seen on my system the corrosion always began between the rubber hose and the aluminum union or convector pipe. It only made it to the inside of the pipe/union AFTER eating it's way through from the outside. This gives me a bit of hope that it might not present itself to be a problem inside the boiler.

To your 2nd question, my friend with the inspection scope has not gotten his scope working yet so I have not been able to peek inside the boiler yet. There are no obvious signs of any problem where hoses connect to the boiler but those connection are to stainless steel and not aluminum. I think it is the water jacket/tank in the boiler that is aluminum. I do plan on doing my best to inspect the aluminum parts inside the boiler but I'll wait to hear from Alde...zzzzzzzz. I still have not heard back from them after their initial response for more info on the boiler. I'll be writing them a 3rd email with a bit more concern today.

fstop32 · April 2021

@ScottG I haven't gotten to sourcing for parts yet. There is a dealer in Huntsville about an hour from me that I will be calling today or maybe driving down tomorrow so I can press the flesh a little better.
I did get a reply from nuCamp, not exactly sure who actually sent it...pasted below...

Thanks for reaching out to us and for being a part of the nuCamp family! I am sorry to see what has happened to your Alde! After discussion with our tech department I have provided their response below.

I would say this comes from not replacing the glycol and not so much electrolysis as it is bad at the convectors and not at the Alde system. We never grounded the ALDE but the 3010 used to have a small glass fuse on the ground wire so if it had any voltage going to the system it would have blown the fuse long before it would cause this kind of corrosion, I would say his best bet would be to replace the convectors and hoses and make sure he flushes the system thoroughly. I hope this helps give some direction on what may have happened. In regards to parts, I suggest reaching our to our parts department at nuparts@nucamprv.com to see what we may have to offer. I will mention that if you do go this route you will have to order through one of our established dealers since we do not sell parts direct. Some of your more technical questions about the Alde I would direct to our tech at tech@nucamprv.com. If you have any other questions please reach out.

Have a great day!
(end of paste)

What arrived a couple of hours later was from Creed Hostetler, a tech support specialist in Sugarcreek OH. ...pasted below...

Hi Dave,

Sorry for the delay – I wanted to speak with QC first.

Correct – the corrosion most likely would have occurred due to not replacing the glycol at the 2-3 year mark. The best course of action from here would be getting the unit to a nuCamp dealer or certified alde repair center to have the affected convectors and hoses replaced, as well as to have a thorough flush of the old fluid and replacement with new fluid.

Kind Regards,

(end of paste)

ScottG · April 2021

@fstop32, thanks again for your detailed description and photos. One of my small bulges was at that same connector near the elbow.

Interesting observation about the progression of the corrosion being from the outside of the pipe (under the rubber hose) to the inside. Maybe I'm not seeing it but the union in your photo doesn't look eaten through--do you think the white powder and the more aggressive-looking salt-like crystals are the same thing?

Hopefully your hypothesis about the condition of the boiler itself is correct. I'm looking forward to results of your boileroscopy when you get the scope working.

Regarding the construction of the boiler, the inner core (where the glycol is located) is reportedly aluminum. It's the outer jacket containing the domestic HW that is stainless steel. Therefore, in theory the glycol is only in contact with aluminum throughout the system.

From my perusal of various U.K sites, it does appear that Alde makes a "boiler refurbishing" kit that includes the boiler core. However, it's about 2/3 the cost of a whole new boiler, and may only be available in conjunction with Alde authorized service. Frankly, if it comes to that the Alde is going on the recycle pile and I will be looking into installing a more traditional RV water heater.

fstop32 · April 2021

Hauling my unit anywhere is not an option for me for a multitude of reasons. I'll continue to verify the condition of the boiler and try to locate a dealer who will be my parts middleman.

@ScottG, did you have a link to the UK place with a US sales site?

General question: Assuming I find my boiler to be ok (and by that time it will be flushed of any residual glycol) and I'll have new hoses and convectors what do you all think of changing to the newly recommended glycol fluid?

fstop32 · April 2021

@ScottG, that union was in pretty good shape comparatively speaking. In looking at the various unions and convectors all the corrosion was confined to the outside layer of the pipes UNTIL it finally ate it's way through to the inside. I don't know if that's because air was seeping into the space between the rubber tube and the pipe or what....?
I don't think the white powder looking stuff and the more aggressive-looking salt-like crystals are the same thing but that's pretty much a WAG on my part.

ScottG · April 2021

FYI, here is a statement from Alde regarding boiler corrosion. This is from the U.K. so references to the extended life glycol are not relevant. You can see the full discussion at www.caravantalk.co.uk/community/topic/118932-alde-water-tank-corrosion/

What can cause corrosion damage in the glycol cylinder?

The heat transfer fluid will accumulate some mineral content from the air, or if tap water is used will contain minerals.

These minerals will attack the aluminium surfaces in the glycol cylinder. For this reason the antifreeze used contains a corrosion inhibitor (or SCA). This coats the surfaces in the cylinder, forming a barrier against the minerals.

The barrier gets worn away eventually, hence antifreeze products are described as having a lifespan, after which they should be replaced.

To avoid corrosion, ensure that the heat transfer fluid is 50% ethylene glycol antifreeze and 50% clean water. The water hardness should not exceed the maximum stated by the antifreeze manufacturer. We recommend using deionised water (0 ppm hardness).

Ensure the heat transfer fluid is replaced before or soon after the antifreeze lifespan has expired. UK caravan and motorhome manufacturers use a 2 year antifreeze as standard. We recommend replacing with a 5 year VAG G13 spec antifreeze, such as Alde Premium G13, Comma Xstream GG40, Triple QX G13, or Motul Inugel G13.

In 2015 Alde repaired 10 corrosion damaged boilers of various ages, from a range of industries: caravan and motorhome, boat, and construction industries. Corrosion damage is costly to repair and can be avoided.

Edited October 13, 2016 by Alde UK

fstop32 · April 2021

Maybe the white powdery layer inside the unions/undamaged convector pipes is the "corrosion inhibitor barrier" (or SCA) mentioned in the statement @ScottG just posted above????

ScottG · April 2021

Ha ha. Great minds think alike, @fstop32! We can hope, I suppose...

Anyone out there with a brand new T@B willing to rip apart your heating system so we can see if the white powder is there from the start? ;-)

@Denny16, what do you think based on your experience with your heat exchanger?

Sharon_is_SAM · April 2021

@ScottG - someone with a newer model posted white flakes in their glycol. I will see if I can find the thread.

No luck.

Denny16 · April 2021

The white powder is an indication of bad glycol causing/allowing a corrosion like reaction to occur with the aluminum and glycol, kind or like a chemical electrolysis. I had to apply an a special anodizing compound to my new manifold to help prevent this issue from happening again.

From what I understand, the Alde boiler is constructed of stainless steel, hence the SS connectors, I do notmthinkmyoumwould have stainless pipes going to an aluminum boiler jacket. Also as the inner boiler where the glycol is is gas fired, it is also made from stainless steel. A good flush of the boiler should clean it out, as Austin pointed out.

This situation shows the importance of replacing the glycol per the recommended two year cycle. PH test strips are not going to test the corrosion inhibitor quality or lack of.
cheers

ScottG · April 2021

@fstop32, I think we were posting at the same time yesterday afternoon, and looking back I realized I missed some of your earlier comments. That could be why the conversation seems a little disjointed. :-)

The responses from nuCamp were sympathetic but pretty generic. In fairness, it's likely they just haven't seen this before and don't have any better answers than anyone else. I'll be interested to hear what they tell you about parts. I was told (by Creed) about a year ago that nuCamp did not provide Alde parts, but perhaps that has changed. Like you, hauling my trailer to IN--or even to some elusive "service center" qualified to do the work--is not a viable option.

The Wet Works is the place in the U.K. that seems set up for shipment to the U.S. There may be others.

I've also wondered about changing over to the new glycol, but have no further information to offer. There has been no indication of why Alde switched brands at the start of the year.

ScottG · April 2021

@Denny16, thanks for your assessment of the deposits. It is well documented (including in the statement from Alde I posted above) that the glycol-containing core of the boiler is aluminum, and the surrounding domestic HW jacket is stainless steel. I do agree that stainless pipes should not be going to an aluminum core, but I have no further idea of what is going on there.

pak · April 2021

I just looked at mine. 2017 cs-s, about 20 miles. The glycol side has not been used that much. Glycol has never been changed and is still clear and ph still tests very high. No bulges, drips or stains.

Denny16 · April 2021

@pak while the glycol tests ok with a PH strip, thst is not going to test the anti-corrosion additive effectiveness. Aluminum parts in contact with the glycol can still corrode. You should drain and refill your Adle system (or have it serviced and glycol replaced by a dealer)! especially since the glycol part of the boiler is aluminum. Why take the risk?

Cheers

pak · April 2021

Sound thinking, I concur.

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