Corrosion of Alde Convectors

DanWeitzel

Sounds like your on the right track.  Might consider using RTV to seal the cap, you would still be able to remove it when needed.

BridgerSunset

@grassgd - there are certainly labs that can analyze things like that white residue, but unfortunately not for free....😮‍💨.

If that stuff is circulating throughout the system, and it probably is, then it probably just clings to any surface with a rough texture, when looked at in a magnified view.  And yes, the uniform pitting seen on various internal surfaces is more of a spread out general pitting.  This differs from the focused "under deposit" (aka crevice) corrosion & the enhanced oxygen differential present under there.  That differential is a driver in a corrosion cell.

I've long suspected there's at least some oxygen relationship in the corroding aluminum.  Your work on that front seems like a good idea &  solid concept.

gulfarea

Would this work? Most of us don't need that much heat except those who camp in the winter up north. Instead of aluminum Alde Convectors how about just using more thin wall rubber hose back & forth under the areas needing heat. Also a shut-off valve to stop heating the extra hose in summer but keep the heat flowing to the water heater. No more Convectors to corrode & less heat under where we sleep in the summer! Just my 2 cents. Art What are your thoughts?

AnOldUR

gulfarea said:

Also a shut-off valve to stop heating the extra hose in summer but keep the heat flowing to the water heater.

Until the thermostat calls for heat, the pump that pushes the glycol through the system is off, so no glycol goes to the convectors. The glycol in the furnace transfers heat to the hot water system without it sending glycol through the "Glycol In" and "Glycol Out" ports pictured below. No additional shut-off valve is needed.

fstop32

Here is a pic of one of my now replaced bleeder valve elbows...white stuff definitely on the hose inside.

gulfarea

AnOldUR Thanks for reminding me about that! Makes changing to longer hose instead of convectors EZ. Where I camp not much heat needed. Thanks Art

Freespirit

Progress update: I was able to get back to inspecting the convectors after discovering corrosion inside the fittings of the Alde reservoir. Here is what I discovered after removing the first convector(top back). 

Some type of jelly like substance in both ends and what I thought was minimal deposits on one end of the convector. 

This is the total substance from both ends. It was attached to the inside of the convector tube and I was able to scrape it out using a straightened paper clip 

The BIG surprise was when I filled the tube with distilled water to rinse the remaining jell out I discovered a hole corroded through the tube. I guess I was lucky in that the hole was covered by the hose and doubled clamped. However when I look down the tube there are numerous bulged in the middle of the tube which will likely develop a hole at some time. 

I need to decide what my next steps will be. 

DanWeitzel

This seems like the first report of corrosion on the inside of the convector tubes, all previous was on the outside of the convector stubs.  Something seriously wrong here!  When I repaired my 2016 there was some penetration of the tube ends but was the result of corrosion on the outside of the tube eating it's way thru.  

AnOldUR

@Freespirit You said that the Rhomar has been in your system for two years. Curious who did the exchange and what method was used?

edit
Never mind. I found your earlier post.

Freespirit

@AnOldUR, I did the flush 2 years ago following the steps @ScottG so well documented. You can read my process I preformed on page 14 of this thread. After flushing the system with 15 gallons of distilled water I decided to replaced EVERY  part of my Alde system with the exception of the boiler. I went back with ALL new ALDE parts from NUCAMP. 

I am beginning to think my system is jinxed. I love the Alde system but the maintenance of my system is beyond ordinary. 

BridgerSunset

@Freespirit,  Your report grabbed my attention &  made me go back and reread this whole thread twice.  Really sorry you're fighting this.....  Thanks for documenting it all.

So to summarize - is this my understanding:

1.  Originally Century fluid, fairly heavy use of Alde
2.  Found corrosion enough after 1 year use to replace all aluminum parts except boiler
3.  New convector stubs (outside) were double clamped, but uncoated
4.  Flushed & changed over to Rhomar after changeout of parts
5.  2 yrs later now found powder and corrosion inside new glycol tank outlets
6.  And now found pitting on outside of convector stub & gel deposits inside
7.  And a hole from outside in
8.  And more deposits seen further inside convector stub

Leaning toward the coating being the missing link here.

grassgd

One observation is the inside of the convector tubes look extremely clean without any of the white power looking substance found in many of the pictures of convectors and the rubber hoses removed from Century glycol service. 

The jelly like stuff is a new one along with pitted holes without a lot of corrosion in the area.

Very strange.

Freespirit

@BridgerSunset, your summation is very complete, two clarification:
#4. System was flushed with original parts in place. After flushing decided to remove all old parts and replace with new. 

#7 From what I can determine, the hole was from the inside to the outside. There were deposits inside the tube where the hole originated and tube on the outside looked original with the exception of the hole. 

@grassgd, your observation is describing what I am seeing. There has been NO evidence of white powder in the convectors or tubes, just what I documented on the reservoir connections. While the inside of the convectors appear clean, I have tried to show what the inside actually looks like. While it is free of white “stuff” there appears to be corrosion inside the length of the convector. 

The new pictures are the bottom convector in the back I removed today. An abundance of jelly stuff in both ends as well as discovering the jelly in the tubing. 

BridgerSunset

Got it, thanks.    So what's your best guess on what's in the jelly cocktail?  Not sure we've  seen reports of that being found in the past.

grassgd

Freespirit said:

@BridgerSunset, your summation is very complete, two clarification:
#4. System was flushed with original parts in place. After flushing decided to remove all old parts and replace with new. 

#7 From what I can determine, the hole was from the inside to the outside. There were deposits inside the tube where the hole originated and tube on the outside looked original with the exception of the hole. 

@grassgd, your observation is describing what I am seeing. There has been NO evidence of white powder in the convectors or tubes, just what I documented on the reservoir connections. While the inside of the convectors appear clean, I have tried to show what the inside actually looks like. While it is free of white “stuff” there appears to be corrosion inside the length of the convector. 

The new pictures are the bottom convector in the back I removed today. An abundance of jelly stuff in both ends as well as discovering the jelly in the tubing. 

Those pictures are very, very concerning.  This appears to be a failure of the basic corrosion protection and not a crevice corrosion issue we have been discussing/dealing with.  

I would suggest contacting Rhomar to let them know what happened and seek their advice if they take an interest.  Perhaps they could test a sample of the 2-year-old glycol if you still have some or a sample of the corrosion and/or aluminum connector or convector.  I would hope they would take an interest in figuring out what happened since their glycol was used.

I also think nuCamp and Alde/Truma should be very interested also since they recommended the switch to Rhomar to correct the corrosion problem we were seeing.

Maybe in light of the fact you purchased all new convectors and followed their recommendation to switch to Rhomar, they may be able to warranty the new materials.

Do you have a flexible scope camera that could inspect the inside of the stainless-steel tank inside the main Alde unit?  I have one but forgot to run it in my unit during my repairs.  That may give additional information as to the extent of the corrosion - only aluminum or both materials.  If you don't have one, perhaps we can work out for you to use mine since we may be near each other.

Freespirit

@grassgd, thank you for your feed back. I will try to contact someone at Rhomar today. 

I left  a message with nuCamp yesterday and am waiting for a call back.                

For three weeks I have been trying to contact someone at Truma/Alde with no luck. I have yet to talk to a person, all calls go to voice mail. I have left numerous messages, used their automated call back option, and sent many email all with no success. I have been trying to contact them daily. 

Your flexibility scope idea is great/appreciated. I do have a flexible scope but never thought to use it for that purpose. I will scope the boiler and let you know what I discover. 

Non-return valve. 

Freespirit

@grassgd, thanks for your suggestion of using a flexible camera!, here are the results:
Bottom connection on the boiler showing clean connection. 

Pictures(2) inside the bottom connection of the boiler. Looks great!
Top connection of boiler showing clean connection. 

Pictures (2) inside the top connection of the boiler. Looks great. 

All the jelly looking stuff has been limited to convectors and non-return valve,(aluminum?). 

ChrisK

I almost wonder if the new convectors were tested at the factory with the old fluid and trace amounts were still in the convectors. Then that trace amount reacted with the new fluid and created the jelly. Just enough that it stayed localized and did not spread to the rest of the system. 

DanWeitzel

It would be interesting to see if mixing the old TF1 with Rhomar would recreate the jelly?  I thought someone did this test in the past and didn't find any issues, maybe Mark Turney?

grassgd

Freespirit said:

@grassgd, thanks for your suggestion of using a flexible camera!, here are the results:
Bottom connection on the boiler showing clean connection. 

Pictures(2) inside the bottom connection of the boiler. Looks great!
Top connection of boiler showing clean connection. 

Pictures (2) inside the top connection of the boiler. Looks great. 

All the jelly looking stuff has been limited to convectors and non-return valve,(aluminum?). 

Relieved to see the boiler look good!

My return valve was originally in aluminum, but I cut the plastic check valve out of the corroded aluminum and inserted it into a short section of stainless steel 7/8 inch marine railing I had which fit perfectly.  I made my connectors out of the same stainless-steel tubing which allowed me to trim the rubber hose ends which were compromised by the budging/corrosion and make up the length with stainless steel.

I can help thinking a worry-free solution would be stainless steel convector pipe with aluminum fins.  I know stainless steel doesn't transfer heat as good as aluminum, but I would sacrifice that for no corrosion in a heartbeat.  I need to talk with my son who use to work in the that transfer industry as a sales rep to investigate this as hail marry option if this continues.

PS:  received the tank----thanks.  Will do some testing next week.

Freespirit

@grassgd, you may have just hit on the next DIY TAB modification.   Using the 7/8 stainless steel marine tubing, slide the fins off the aluminum tube and slide them in the stainless steel tubing. 

pthomas745

We have reached Peak Alde Research!  A Successful Alde Colonoscopy!

Someone would have to prove to me that two different propylene glycol mixtures that are greater than 99.9 percent exactly the same could cause a "jelly".  But, that is just me.  As many stories as we have about various dealers simply pouring in either glycol they happen to have on hand, so far it has not been reported. 

As far as stainless steel is concerned: what are the new connectors in the later model trailers made of?  Their are several pipes in various photos of newer trailer that show very different setups compared to the Alde 3010 models.

The photo below is a 2021 400 showing the pipes I mentioned.

BridgerSunset

@Freespirit
Having deposits & pitting & the subsequent hole on the inside of the convector stub tells me this - that the same "under-deposit" attack mechanism is still responsible.  Again, corrosion inhibitor needs to be constantly present and replenished to work.  If the Rhomar's inhibitor can't get to the aluminum because the aluminum is covered up by goop, then it can't protect the aluminum.  The accelerated pitting from the inside-out is harsh, but does make sense in that setting.

That part is actually good news....in that we shouldn't lose faith yet in the Rhomar;   and that the double clamps did their job.

Glad the boiler looked clean!

Now to decipher why the jelly goop formed or accumulated there, and how to keep the system clean.

Freespirit

An option for replacing convectors, combine with 7/8 or 1 inch stainless steel marine railing, double clamp to hose and see what happens. 

cafyrman

I've been wondering if buying new convectors and them having them anodized might be the answer.  If the fins come off that easily, I'm even more tempted. But I'm also tempted to just replace with stainless.  Hmmmm.

The stainless won't conduct heat like the aluminum -- but I live in far SW California.  My trailer has never seen temps below 20F.

rh5555

Look out!  Stainless Steel is notorious for crevice corrosion - just as bad as aluminum.  It needs constant access to oxygen to stay stainless.  

grassgd

Freespirit said:

An option for replacing convectors, combine with 7/8 or 1 inch stainless steel marine railing, double clamp to hose and see what happens. 

Where did you find that?

grassgd

rh5555 said:

Look out!  Stainless Steel is notorious for crevice corrosion - just as bad as aluminum.  It needs constant access to oxygen to stay stainless.  

I guess I should have epoxy coated the ends of my stainless steel homemade connectors. 

Freespirit

@grassgd, they are called fin clamp baseboard element. Home Depot, Amazon and others have them. They come in different pipe diameters and lengths. 

cafyrman

rh5555 said:

Look out!  Stainless Steel is notorious for crevice corrosion - just as bad as aluminum.  It needs constant access to oxygen to stay stainless.  

Hmmm. OK.

So does anyone know if the Alde connectors are clear anodized from the factory? Or would that maybe help?