Alde Fluid

cid69 · January 3

Ok, so the recommendation is to change fluid every 2 yrs because fluid looses anti corrosive properties. Does this mean Aldi fluid has a shelf life? Or does it loose those properties because of use. Can I use an open bottle of fluid that is over 2 yrs old?

Freespirit · January 3

@cid69, FYI only, I sent a 2 year old unsued sample of Rhomar fluid to the Rhomar lab for testing and below are their test results:

pthomas745 · January 4

This group has asked questions and brought up issues of the glycol for the Alde for over 9 years now. What we have learned about the glycol itself is it appears to be a very stable solution of propylene glycol and distilled water. Numerous owners have tested the PH of the glycol that has come out of their trailers and found it to be just like what Freespirit above found in his test results. The search below is group threads that mention "Alde PH", and you can see what I mean. The PH seems to be very stable.

https://www.google.com/search?q=alde+ph+site:tab-rv.vanillacommunity.com&client=firefox-b-1-d&hs=JyQU&uact=5&oq=alde+ph+site:tab-rv.vanillacommunity.com

Both of the glycols that owners have used in our Aldes are virtually identical, based on their "Safety Data Sheets". Propylene glycol and distilled water in roughly a 50-50 mix...with the only difference being the "corrosion inhibitors" listed in Freespirit's report. The difference in the levels of inhibitors in the Century brand glycol and the "Truma Alde" glycol (which is just rebranded Rhomar Rhogard RTU50) is about 2-3 percent of the entire solution. What is interesting in Freespirit's analysis is they actually tell us what the inhibitors are. All of the manufacturers list their combinations of inhibitors as "proprietary" information, or, trade secrets. Except for the small percentage difference in the various inhibitors, and the dye that each manufacturer uses, it would seem...maybe...that the glycols are essentially the same.

The inhibitors are important, but the way they work inside the Alde aluminum parts of the glycol loop is interesting. There is one Mark Turney video that digs pretty deeply into how exactly the corrosion inhibitors do their job, and the real reason that the corrosion formed under the poorly clamped hoses at the ends of the convectors, etc. I don't think any owner who had to clean up their convector stubs has ever found the insides of the aluminum "tubes" that carry the glycol to have any damage at all. Which would make me believe that the corrosion inhibitors in the glycol in my trailer was doing the job. Except for the glycol trapped under the clamps. Watch Mark Turney's video here. At about the 8 minute point he gets into what the corrosion inhibitors do.

https://www.youtube.com/watch?v=_0mRXz9m-5s

manyman297 · January 4

@pthomas745 Yeah, it’s really interesting seeing these lab tests. I’m overdue on my glycol exchange (just a Rhomar to Rhomar swap). Next summer will be three years. So far I don’t see any evidence of bulging on the connectors. Of course who knows what’s going on elsewhere but my gut tells me these glycols could probably last several years in use. Whatever the issue is obviously has to do with the trapped glycol on the convectors.

dlb · January 5

So when you flush the old with the new does it actually do anything to the trapped fluid? Just a thought.

pthomas745 · January 5

"Flush" is a bit confusing: if you change from one glycol to the other, the "flush" is supposed to be with a distilled water "flushing" to clear out the "old" product. If you are simply changing out the glycol with the same product in the trailer, that would be more of an "exchange".

There are more than a few owners who have realized that all that is really happening with any of these "changes" is the replenishment of the anticorrosion additives. They just "drain and replace" the glycol in the trailer. The 320 holds about 3 gallons of the glycol. If an owner simply opens the drains and gets half of that glycol out, and simply replaces it, the idea is that the anticorrosion elements in the glycol have been "replenished" and they are done. This owner, several years ago, did a little math about a 400:

"I’ve read (or skimmed) most everything I could find on changing glycol in the T@B and see a mix of great DIY ideas, high costs from dealers and lot of hesitancy to dive in and try a DIY solution. Throw on top of that the unknowns about the need to switch to the new Rhomar fluid and it can cause analysis paralysis or just plain denial of the need to do anything – at least it did for me.

After getting through the denial phase and considering the uncertainty of the need to do a complete flush and switch to a new fluid, I thought I could easily handle a gravity drain of the system through the drain plug, and a refill of the system. I wondered, however, just how effective this would be. To figure this out, I drained what fluid I could from the system via the rear drain -- managing to remove 6.5 quarts of glycol (2019 T@B 400). Using a total capacity guestimate of 15 quarts, I calculated that each refill done in this manner would leave 57% of whatever fluid was in the system to begin with and add 43% new fluid each time. Assuming an exchange of this type each year and starting with 2-year-old fluid, the average age of the fluid just prior to the yearly exchange starts at 2.0 years (prior to initial exchange) and slowly rises to and average age of 2.3 years prior to the 10th annual exchange.

I’m not certain that the average age of the fluid is a precise indicator of its quality, but the calculations gave me the confidence that I could do a simple drain and refill each year without much risk of damage to the system. All this, of course, pending any new info on why Alde is recommending a new type of fluid, and pending my need to tinker with pumps, shop vacs, low-point drains and all the other great ideas that are posted in this forum.

For me the partial exchange approach is at minimum a short-term solution that takes little skill or time, and the only cost is the fluid itself. I’d love to hear any thoughts, especially on the assumption that the average age of the fluid is a reasonable indicator of quality."

In my 2017, I found it very difficult to perform the Tab Yoga needed to work in the very limited space where the Alde expansion tank is. I decided to use the process described in "Appendix A" of the DIY Glycol exchange file. I simply disconnected the hose where the non return valve exists next to the Auto Air Bleed valve. In about a minute, I was able to drain all of the glycol from that point, through the glycol loop, and back to the expansion tank and out to the open drain. Unfortunately, I did not measure how much I took out of the trailer. There was probably some glycol inside the Alde unit itself. With the glycol drained this way, when I took the convectors out to clean the corrosion, I found nothing but drips from the hoses and convectors. I'm reasonably sure I removed at least 70 percent of the glycol in my system with this method. When I do it again in the spring, I will be more careful with making some good measurements.

We have also continued to learn the real reason for the glycol corrosion, which Mark's video describes. Poor clamping, poorly fitted hoses, and unprotected stub ends were the real culprits.

cid69 · January 5

Wow, I didn't realize I would start such an interesting thread. Thanks all for your input. I'm not a scientist, nor really technically savvy. I keep looking for something to convince me that the 2 year exchange mantra is credible.

Arguing against that a lot is the the testimony above.... (1)Alde fluid is pretty stable and does not have a short term shelf life. (2) There is no reported corrosion of the Alde system outside of the ends of the convectors and that is most probably due to improperly clamped hoses.

So, if you have a unit that is several years old and no corrosion issues at the convector ends you may not need to change the Alde fluid at all??

While that logic seems pretty sound, I think I will opt for a simple drain and refill every 2-4 years, out of an over abundance of caution.

P.S. I just had a complete fluid exchange done in the last 30 days and that's what got me thinking about all of this.

AnOldUR · January 6

pthomas745 said:
We have also continued to learn the real reason for the glycol corrosion, which Mark's video describes. Poor clamping, poorly fitted hoses, and unprotected stub ends were the real culprits.

I've not seen verified testing to confirm that Mark's theory is correct, but there is logic to it. I believe that both things can be true. Glycol penetrating around the stub ends is causing corrosion and that a better formulated glycol product will reduce or eliminate that problem. Will the new Alde fluid be this product? For now, there's only anecdotal evidence one way or the other. Doing both, putting a second clamp right at the end of the convector and using the new glycol is probably the best advice.

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