Alde Expansion Tank Empty

madhatter1620 · March 14

We were camping in average 30 degree weather for a week using Alde set at 70 degrees. We left for 3 days with Alde set at 68 degrees on electric. Expansion tank was filled closer to Max than Min, so thought it would be fine. Upon return the expansion tank was empty and the Indoor temp was about 45 degrees, just a few degrees above outdoors. So I turned it off. We have had our 2019 TAB 400 for about 2 years. All I have done with the Alde is top off the expansion tank a couple of times.

Back home I started reading the discussions and then searching for a leak. Have exposed the convectors, except for the one in the kitchen and the shower floor, enough to at least feel the connections and look for leaks. Have found no evidence of one. Drained the glycol and got just short of a gallon out. Was about to Exchange the glycol using ScottG's procedure from May 2021.

Have read that if you run the Alde low on glycol it can burn up the heater. Anybody had this experience? Is there anything else I should look for or check before doing the exchange?

pthomas745 · March 14

A leak would be obvious. There may be enough glycol in the "loop", but just not enough to be seen in the glycol tank.

Places the glycol can be tossed out of the trailer to look at: the Auto Air Bleed Valve could have been stuck. Did you notice a puddle under the trailer? The "Auto Air Bleed Valve' is the brass fitting on the side of the Alde. The black tube from that fitting goes to the "grommet" in the floor, and drains under the trailer.

The Alde, when really low on glycol, will send out an "Overheat" error and stop. So, running the Alde won't necessarily "kill" the Alde.

If you have the glycol, you can refill the tank, turn on the Alde, and check for that stuck Auto air bleed valve.

madhatter1620 · March 14

Could not tell if there was a leak due to the fact that the camper was parked over dirt and there was melting snow flowing under it. Have 5 gallons of glycol. Still need to acquire the stoppers and copper to make the adapters for the glycol exchange.

Should I do the exchange or just fill the tank to test the valve? If it is a stuck valve, can it be unstuck or will it need replacing? Thanks!

qhumberd · March 14

@madhatter1620 I would fill the tank and identity the leak before pouring in more of the expensive glycol. Also check under the shower by removing the panel under the shower to see that convector space. The kitchen requires a bit more disassembly to see that one but the floor should be wet under that cabinet. As @pthomas745 mentioned, identify the black tube from the overflow valve which has some clear tubes with it going to the grommet in the floor and feel if there is glycol there. Here is a good diagram on the Alde in the 2019 if you have the Flow unit:

Image: https://us.v-cdn.net/5021717/uploads/editor/n6/9rxszgniscmi.jpg

Is your glycol the Century type or the Rhomar?

pthomas745 · March 14

If your plan is to change the glycol, find some distilled water (distilled, not "tap" water) and try bringing the expansion tank up to a decent level. Watch to see how much distilled water it took to refill the tank. If it takes more than a gallon......that would indicate some sort of leak, since the entire loop in a 400 might have 3.5 gallons in it.

With the tank refilled, you can try to run the glycol pump "continuously" to circulate the glycol around the "loop". The Alde does not need to be "heating" while you do this: you only need to find the pump setting in the Alde Tools menu, and set it to "CONT" instead of "Therm". This just starts the pump and moving the glycol around while you have a look for leaks. If you have the "DIY Glycol" document available, that procedure is listed on page 6.

Picture below shows a 2023 400 with the "grommet" in the floor. The black hose is the one from the Auto Air Bleed Vavle (the brass fitting). One clear hose is from the hot water tank drain vent on the side of the Alde. The other clear hose runs to the expansion tank itself. The expansion tank hose acts as another glycol escape route. If the glycol was overfilled, or the system "backed up" in some catastrophic way, the glycol could come out of the top of the tank and come out of that clear hose. It is normal for "some" residue to be in that hose, due to the trailer rolling down the road and the glycol sloshing around a bit.

madhatter1620 · March 14

My setup is exactly the one you pictured with the flow unit. I am using the yellow Century glycol. Off to get some distilled water and parts for the adapter.

Horigan · March 14

@madhatter1620, If you have a 2019 with the large closet and the reservoir in the corner, you don't need to use the Scott method. Just drain the fluid from below the Alde and remove both hoses from the reservoir. One hose will be filled with fluid due to the check valve in the system (have a large towel and bowl handy). Duct tape a shop vac hose to that Alde hose and pull/vacuum the remaining fluid out.

PS: My fluid level never really changes, so you do have a leak somewhere.

vhollow · March 14

You might remove the access panel in the bottom of the closet and feel the Alde hoses where they go under the bathroom from the closet floor. That is where the leak in my 2018 400 began.

madhatter1620 · March 15

So today:

I exposed the convector under the shower and put a bucket under the camper where the "grommet" is. Added about 1 1/2 gallons of distilled water to the expansion tank to get a bit above MAX, note that it had been previously drained of glycol.

Turned on Aldi with pump set on "CONT", expansion tank dropped about an inch. Could hear and feel that the pump was running. Added a bit more water to the expansion tank and left lid on but not closed. Released the air from the manual bleeder.

Over the next 3 hours I checked it for leaks and found none including in the bucket below the bleeder valve "grommet". No change in level of the expansion tank. Seemed to include more glycol in the water than I would expect.

A bit perplexed. Did tap the automatic air bleeder a few times once I learned about it. Another thing I did not mention is that at one point, prior to leaving the Alde running, there was a 5 inch icicle coming from the Alde vent. Will be out of town tomorrow, so time to think about next steps...

Horigan · March 15

I know you mentioned running on electric in the original post. Did you run it on propane on the recent test? If so, there is a lot of water vapor in propane combustion gases, so that could explain icicle.

If it's cold enough for icicles, you should consider draining the water if you're away.

madhatter1620 · March 16

@Horigan, Thanks for the explanation of the icicle. I did have it running on propane for the first few days and then switched over to electric. No longer in icicle weather. Also, I do not own a shop vac and already have what I need for the Scott method.

My plan is to try it out first with distilled water for the experience. Then let it run for a while on CONT just to double check for leaks.

Thanks to all for the education!

madhatter1620 · March 21

Found the leak behind the bench seat on drivers side. Corrosion got bad enough to crack the hose.

Image: https://us.v-cdn.net/5021717/uploads/editor/x2/t0f74woc1n3o.jpeg

Also note that there is a bulge starting at the connector just under the leak.
Removed the convector:

Image: https://us.v-cdn.net/5021717/uploads/editor/my/1tpu52ie21m9.jpeg

This is the side of the convector where the leak was after cleaning off the loose stuff. There is one pinhole, so you can see corrosion starting on the inside. The other side of the convector showed some discoloration but no "loose stuff" . This made me start looking at the rest of the connections of the tubing. Already removed the convector under the bed which was not quite as bad but close.

Two other places that concern me are the connector where the pump is prior th the Alde Flow and another short section near the Alde where I believe the check valve is.

Image: https://us.v-cdn.net/5021717/uploads/editor/ys/bp49kpo3062b.jpeg

Image: https://us.v-cdn.net/5021717/uploads/editor/6j/d6mvxacwndsu.jpeg

Most of the other connections seem to be okay, but will definitely be inspecting them on a regular basis in the future.

Have been reviewing @grassgd 's post:
https://tab-rv.vanillacommunity.com/discussion/18434/how-to-repair-corrosion-on-aluminum-convectors#latest

Plan to do something like this. Curious if anybody else has tried it and what they used to clean and coat the convectors/connecters. Also about replacing the connectors with the stainless steel 7/8" marine railing.

pthomas745 · March 21

Good detective work! There are tons of posts about "corrosion of the Alde convectors", with various solutions. Basically, the stub ends or aluminum parts are cleaned off and "sealed" in some way. And then replaced with the clamps in the proper place at the "end" of the stubs, and not in a place that allows the glycol to be trapped under the hose. The solution by the owner in the thread you linked to is one of several that use the same basic approach. Other owners have used things like shrink wrap, etc. This is the "Corrosion of the Alde Convectors" thread. If you page backward through it, you will see what other owners have done to mitigate the damage. Link goes to the last page, just skip back in time and see the photos of what owners did. Lots of discussion about the glycol, etc.

https://tab-rv.vanillacommunity.com/discussion/13226/corrosion-of-alde-convectors#latest

This Mark Turney video goes in great depth to explain what is happening with the corrosion, and goes a long way to define exactly what the glycol is, what the anticorrosion substances are, and what they do. In the second segment of the series, he shows how they should be cleaned, coated with "Magic Paint" and clamped properly.

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

Grumpy_G · March 22

Just watched the videos and while it's mostly sound I guess he's not a mechanical engineer

In part 2 he argues against the hose clamps that Nucamp uses because they are "used for faster assembly". Bzzt wrong ! They are called constant tension hose clamps and are widely used in the automotive industry because they provide consistent clamping force regardless of thermal expansion/contraction and long term deformation of the rubber hoses.

It might be useful to double up the clamps with one right where the pipe starts and one a bit further down. He also recommends moving the clamp.

Freespirit · March 22

@madhatter1620, there is a lot of great reference material you have to sift through. Owning a TAB 320 for 6 years and performing 3 ALDE system flushes, it is not only what you can easily see but what is not easily visible that may lead to issues later.

Latest flush revealed obvious corrosion on the convector tube ends, decided to look deep inside the convectors and discovered what looks like the beginning of corrosion based on my previous observations. To my untrained eye, the top and sides of the tube look good, bottom of the tube where the ALDE sits showing signs of pitting. Replaced all convectors.

Image: https://us.v-cdn.net/5021717/uploads/editor/q3/25ui6r1dx0w9.jpeg

Didn’t want to replace more parts than necessary so decided to look at the reservoir connections. Out flow connection from reservoir.

Image: https://us.v-cdn.net/5021717/uploads/editor/rz/1ik9zr4v53or.jpeg

Inflow connection to reservoir.

Decided to replace reservoir.

Pictures were taken using an Endoscope camera attached to iPhone, quality of pictures does suffer a little.

Good luck with your ALDE fix.

madhatter1620 · March 24

Thanks so much to all for your inputs! Not prepared to take the entire system apart at this point; want to be able to do some camping. Have removed the reservoir and all the tubing from it to the convector under the bed. Also, what I can reach at the convector behind the bench seat where the leak was. Found that the connectors that were parallel to the floor were much worse than the ones that were vertical. The connectors were corroding from the outside but the valves were corroding from the inside as well. I plan to fix up those areas and then see how it works before working on the rest of the system. Contacted Truma service (877-860-9814) for parts. At first they said I had to go through a distributer but then said some things they could ship direct. Have 25 of the plastic connecters ($1.55 each) and 2 "non-return valves" ($9.11 each) on their way. They only had the valve in the 90mm length.

Mark Turney's videos were fantastic, especially for understanding what is happening. Not prepared to buy a quart of the miracle paint ($55) since I will probably be taking the rest of the system apart winter after next, baring another issue prior to that. Plan to use several coats Rust-Oleum self etching primer ($10) for now on the convector ends and the valves, and doubling up on the clamps there. The rest of the connectors will be plastic. Once it is all together again, I will flush with distilled water prior to refilling with the yellow Century glycol.

Any additional inputs are appreciated. Thanks again!

Freespirit · 12:13AM

I order all my Alde parts through Missouri Teardrop Trailers. All they need is the part number, generally available on the Truma site. They are FANTISTIC.

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