Alde leaking as it heats.

I just bought a 2023 tab 400 and brought it home. Reportedly a once or twice used trailer in late 2023 and winterized in late October. 

As I was looking it over, I saw that the Alde fill reservoir was almost empty. Green fluid barely visible in the neck.  It was 30 degrees out and I turned it on using propane to see if it would work. It fired up fast, burbled on and off, the fan was running on and off, and the cabin was heating up. 

I looked at the reservoir and it was almost full to the top!  It was still heating and so I left it on for another 15 minutes. When I shut down, the reservoir was warm and near full. It had heated nicely.

It was then I saw a stream of liquid that had come out below the reservoir on the drivers side onto the driveway. 

Is it over full?   Missing an air pocket? (I swear that is for hot water, not glycol). How can I diagnose?

thanks. Have been reading like crazy. Seem to have seen this symptom before, but no clear answer to the issue. 
2023 Tab 400
2015 Audi Q7 TDI
Northern Ohio

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Comments

  • swiftwaveswiftwave Member Posts: 31
    A similar thing occurred to the Alde in my T@B 400.
    I believe it was caused by air bubbles expanding in the glycol.
    The problem was resolved by turning the Alde glycol pump up to full speed for a few minutes.  I could hear the bubbles flowing through the system, eventually becoming released to atmosphere once they reached the reservoir.
    After a few minutes, I turned the pump back down to the 2 setting (5 is full speed).
    I also gently tapped on the automatic air bleeder (located above the glycol pump) in order to bring that device back into proper service.
  • RobermcmRobermcm Member Posts: 34
    edited March 21
    Other factoids that might help. 

    Water heating was turned off, system still winterized. 
    Heat was coming out nicely from each radiator, rear, sink, dinette. 
    Alde settings had no water heating, no electric heating.
    trailer is generally level, but may be biased a bit towards the high point reservoir. 
    Oh - I DID have Alde flow highlighted in the check box. 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • Yoshi_TABYoshi_TAB Member Posts: 370
    edited March 21
    Hi,

    The Alde fluid level should be checked on a cold system.   It should be 1 cm above the min. level when cold.
    2021 TAB 320 BD
    2021 Jeep Grand Cherokee
    Southern Maryland
  • RobermcmRobermcm Member Posts: 34
    At about 35 degrees outside, the fluid was at the neck, a few cm short of proper level. After I ran it, it spilled all over the driveway and then cooled, it’s still showing at the neck level in the reservoir. 

    I just read that a pump set at too high a speed could make the fluid leave out the overflow tube.  I’ll check that, and refill cold to proper level. 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • RobermcmRobermcm Member Posts: 34
    swiftwave said:
    A similar thing occurred to the Alde in my T@B 400.
    I believe it was caused by air bubbles expanding in the glycol.
    The problem was resolved by turning the Alde glycol pump up to full speed for a few minutes.  I could hear the bubbles flowing through the system, eventually becoming released to atmosphere once they reached the reservoir.
    After a few minutes, I turned the pump back down to the 2 setting (5 is full speed).
    I also gently tapped on the automatic air bleeder (located above the glycol pump) in order to bring that device back into proper service.


    It was indeed bubbling actively in the reservoir. So maybe that was it. I’ll try the pump speed change and see if that does it. 

    Thanks!
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • pthomas745pthomas745 Moderator Posts: 3,641
    There are two places the glycol can escape.  The first one is explained in the previous comments, "slopping out of a too full tank." 
    The second is a "Stuck Auto Air Bleed Valve."  The big brass fitting on the side of the Alde has the glycol move through it.  Not sure how it works, but the idea is the valve will allow air to escape.  There is a black tube running from the Air Bleed Valve to a "plug" looking thing in the floor of the Alde compartment.  This is the same plug the Alde expansion tank overflow tube goes to. (You should check this tube to see if there is glycol in it...a little is normal).  The other clear tube in the plug goes to the red valve on the side of the Alde.  This valve is an air vent for the Alde hot water tank.

    If the Auto Air Bleed Valve fails, and sticks in the "open" position, glycol just passes through the system and runs out under the trailer through that black tube.
    So, have a good look at your Alde compartment.  Find that black plug, and the black tube and clear tubes.  If you continue to have issues with glycol flowing out of the trailer, and it is not the "Escape From The Expansion Tank" idea, then you have a stuck Auto Air Bleed Valve.

    Here is the thread that explains this. 

    2017 Outback
    Towed by 2014 Touareg TDi
  • RobermcmRobermcm Member Posts: 34
    There are two places the glycol can escape.  The first one is explained in the previous comments, "slopping out of a too full tank." 
    The second is a "Stuck Auto Air Bleed Valve."  The big brass fitting on the side of the Alde has the glycol move through it.  Not sure how it works, but the idea is the valve will allow air to escape.  There is a black tube running from the Air Bleed Valve to a "plug" looking thing in the floor of the Alde compartment.  This is the same plug the Alde expansion tank overflow tube goes to. (You should check this tube to see if there is glycol in it...a little is normal).  The other clear tube in the plug goes to the red valve on the side of the Alde.  This valve is an air vent for the Alde hot water tank.

    If the Auto Air Bleed Valve fails, and sticks in the "open" position, glycol just passes through the system and runs out under the trailer through that black tube.
    So, have a good look at your Alde compartment.  Find that black plug, and the black tube and clear tubes.  If you continue to have issues with glycol flowing out of the trailer, and it is not the "Escape From The Expansion Tank" idea, then you have a stuck Auto Air Bleed Valve.

    Here is the thread that explains this. 

    Awesome.  Making it finite is so helpful. Also improves the hopeful part too!
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • RobermcmRobermcm Member Posts: 34
    edited March 23
    Here’s a discovery under the drivers side rear alde compartment. It looks practically closed off. Inbound (?) pex to sureflo pump. If that’s the water pressure pump?  I believe so, which makes it not related to my alde leaking issue. 
      
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • pthomas745pthomas745 Moderator Posts: 3,641
    That is the water pump, yes. I can't get my head to the proper angle to figure out which way is up!  I can "flip" the photo for you if needed.  That does appear to be the inlet to the pump.  Note the plastic holder with the filter there.
    Can you show us a wider view?

    2017 Outback
    Towed by 2014 Touareg TDi
  • ScottGScottG Administrator Posts: 5,408
    Robermcm said:
    At about 35 degrees outside, the fluid was at the neck, a few cm short of proper level. After I ran it, it spilled all over the driveway and then cooled, it’s still showing at the neck level in the reservoir. 
    ...
    @Robermcm, can you clarify this? There are arguably two "necks" on the expansion tank. Did the fluid rise during operation, and then go back down after the system cooled? Or did the fluid rise during operation and then stay high after the system cooled?
    2015 T@B S

  • RobermcmRobermcm Member Posts: 34
    edited March 22
    That is the water pump, yes. I can't get my head to the proper angle to figure out which way is up!  I can "flip" the photo for you if needed.  That does appear to be the inlet to the pump.  Note the plastic holder with the filter there.
    Can you show us a wider view?


    ****

    Sorry, bad pic.  That is one end of the water pump feed. The inline filter is between the kink and the pump. I’ll want to fix that kink, but later.  Back to my Alde issues…..

    I opened the Alde cavity. Dry as a bone.  I found the Alde pump and the 1-5 settings. Per Swiftwave, I tried the faster pump settings right after turning on the heat via propane. The faster pump didn’t seem to do anything. I ran the system for 45 minutes and had no leaking like yesterday. I did NOT replace the lost Alde fluid from last night and the cold level in the reservoir was about the same as last night before the leak. Odd. 

    To Scott’s G’s questions - the neck I refer to is just below the MIN mark. Just south of where the tank widens into a reservoir. And last night the fluid level grew to a roiling pot of glycol in the reservoir near the filler cap and then settled back to almost empty when it was cold again this morning. I think that’s where it leaked last night given my check of the air valve in the Alde cabinet this morning. 

    So…when I ran it today, it seemed completely ‘normal’ except that it didn’t carry hot glycol beyond the flow tank. The tube from Alde boiler to flow was hot. The tube from flow to the rear radiator was cold. This after a full 45 minute propane run. All things in the Alde panel seemed normal to me. 
    - Glycol temps run in the mid 100’s,
    - water temps, even though still winterized and water heat turned off, rose to lower 100’s
    - pcb temps slowly rose to over 100
    - pump ran on and off at varying speeds, even though set to ‘2’ after the brief higher setting. 

    I’m surmising from all this that I have an airlock, which explains why the fluid still shows in the reservoir after dumping a quart or so last night. 

    Sorry for the length. Trying to provide full content. Eager to understand this.  
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • pthomas745pthomas745 Moderator Posts: 3,641
    Trying to picture where you find warm hoses and where you find "cold" hoses.  If you had the Alde on, the glycol flows out of the expansion tank, down to where the pump is, through the Alde itself, where it heats.  The glycol comes out of the Alde, passes through the Auto Air Bleed Valve.  Just after the Bleed Valve, there is another fitting that is a "Non-Return" valve, or a check valve, that prevents the glycol from moving back into the bleed valve. The glycol then travels around the trailer, and winds up going back into the glycol tank. 
    With the Alde warm, find that spot near the Bleed Valve.  The bleed valve should be warm...and that warmth should travel all along the hose that comes out of the valve. 
    There have been instances of the non return valve being installed "backwards" which would prevent the glycol from flowing away from the bleed valve.
    2017 Outback
    Towed by 2014 Touareg TDi
  • RobermcmRobermcm Member Posts: 34
    I’ll take some pictures tomorrow. Good ones this time. And explain what I’m seeing and where the heat is/isnt. Thank you for helping. 

    The system worked fine at heating all registers last night, it just bubbled over and lost some fluid. Today, I can’t get heat out of the Alde system to travel. I’m learning stuff though!
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • RobermcmRobermcm Member Posts: 34
    Okay, this is embarrassing. Like, a lot. Apologies to Paul and Scott for wasting their intellect. 

    I have been perplexed about why my Alde wasn’t heating. At first it spewed glycol out the reservoir after heating okay. Then it was running but not transferring heat to the radiators. 

    Why?  My Alde reservoir was too low. From the first time I turned it on. Lower than the ‘MIN’. Lower than the exit tube of the reservoir tubing. How dumb to overlook that. I guess I was using the brake master cylinder mind frame. But this system flows through the reservoir. So all I was doing was adding air. The first time it ran, it added air and then got violent. The subsequent times, it was too air filled to move fluid at all. The top glycol tube that goes into the boiler was dry. The pump fortunately was wet. Alde fluid on order to confirm this thinking and fix my heating system. 
      

    Side question - is there anything other than Alde brand fluid that is compatible, corrosion resistant and environmentally friendly? I’m sticking with Alde brand for now. One big dumb moment is enough for a bit. 🥴
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • ScottGScottG Administrator Posts: 5,408
    edited March 23
    No apologies necessary, @Robermcm. I'm glad you figured it out, and I agree with your hypothesis. Once you top up the fluid and get all that air burped out, I suspect everything will work swimmingly once again.
    My understanding is that the current "Alde" brand fluid is Rhomar Water RG-RTU-50. However, prior to early 2021 it would have been Century TF-1. So, just make sure whatever "Alde" fluid you get is the newer Rohmer (which should be what came in your 2023). 
    Apparently the two are NOT compatible, and the same probably applies to other brands of transfer fluid as well. I agree sticking with Alde's recommended fluid--however pricey or hard to get--is your best choice.
    2015 T@B S

  • pthomas745pthomas745 Moderator Posts: 3,641
    @Robermcm glad you sorted things out.  The "new" Glycol is now being sold as "Truma Alde Glycol" at this ridiculous price.  You may also be able to purchase through a NuCamp dealer.


    Missouri Teardrops is pretty good at ordering things from NuCamp and delivering them to your door. So, check to see if their prices are better.


    2017 Outback
    Towed by 2014 Touareg TDi
  • RobermcmRobermcm Member Posts: 34
    Thanks much. I was able to order glycol directly from the nu_camp website. Pricing about the same. I’m 90 minutes from the factory and may drive there to avoid shipping when it’s time for a flush! 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • RobermcmRobermcm Member Posts: 34
    I was topping off my Alde reservoir and it kept accepting it. An entire gallon.  This trailer was used and I just bought it. The reservoir was below the min mark when I got it. 

    Before I went out to get another gallon, I thought I’d check the winterization, so I opened the hot water yellow valve, the cold water yellow valve and the 3 outside valves (hot, cold, fresh). Water with pink antifreeze ran out for a bit. But the hot water line kept running. I gathered some of it in a clear container and it’s almost pure Alde green glycol!🥴

    is my boiler shot or maybe the flow heat exchanger? Clearly glycol is on the hot water line. How should I diagnose more, or is it already a done deal? I’m screwed?
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • ScottGScottG Administrator Posts: 5,408
    edited March 28
    @Robermcm, I moved your comment here from the other discussion where you had posted it. Despite the relevant title, that discussion was a couple years old and involved a somewhat different issue. I think you will get more useful assistance keeping the history together here.
    Unfortunately, what you describe sounds like it could be a breach between the Alde's glycol and hot water chambers. The two systems are entirely separate, and the boiler core (or the Flow core) are the only places where a leak might cause their contents to commingle.
    It's happened to a few other owners, although typically it's pressurized hot water that forces itself into the (non-pressurized) glycol loop. This causes the glycol reservoir to fill and overflow--a symptom consistent with your original complaint above.
    However, I suppose it's possible that as the system cools or hot water pressure is relieved that the leak could reverse and pull some glycol into the hot water lines.
    2015 T@B S

  • ScottGScottG Administrator Posts: 5,408
    @Robermcm, just in case you haven't seen it, here is another discussion (with great photos) of other cases of leaking Alde boiler cores. One owner had their core replaced by Truma/Alde, the other made a successful DIY repair. Note that these were both on 320s and therefore did not have the additional variable of the Alde Flow (another potential leak point).
    Please note I am not certain that this is your problem, However, I can't think of any other way that glycol could get into the hot water system. Even if you had a bunch of valves in the wrong position, fluids from the two sides still shouldn't mix...
    2015 T@B S

  • RobermcmRobermcm Member Posts: 34
    ScottG said:
    @Robermcm, just in case you haven't seen it, here is another discussion (with great photos) of other cases of leaking Alde boiler cores. One owner had their core replaced by Truma/Alde, the other made a successful DIY repair. Note that these were both on 320s and therefore did not have the additional variable of the Alde Flow (another potential leak point).
    Please note I am not certain that this is your problem, However, I can't think of any other way that glycol could get into the hot water system. Even if you had a bunch of valves in the wrong position, fluids from the two sides still shouldn't mix...
    Thanks. I just spoke with nu_camp tech. Helpful guy. He was pretty black and white - likely the boiler (flow tanks tend to leak into cabinet space) and likely from poor winterization process. 

     I guess it could have cracked, THEN they winterized. Would explain the high concentration of glycol in what came out. I put that there when I ran the system with low glycol, that got lower. 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • ScottGScottG Administrator Posts: 5,408
    edited March 28
    Thanks for the update. The amount of glycol loss you describe--combined with the fact that it's glycol leaking into the hot water system--does imply a pretty good-sized breach in the boiler core. Unfortunately the only way to tell for certain is to pull it out and take a look around. Good luck, and please keep us posted as to how this evolves.
    2015 T@B S

  • RobermcmRobermcm Member Posts: 34
    Small update. I talked to Alde out of Elkhart, IN about my problem. I live a little over 3 hours from there.  They offered to have me come over on appointment and they’d fix it that day. If it shows a freeze crack, I pay. If it shows a defect, sounds like they’ll cover it. Suspect I’ll pay.  Their hourly rates, although atrocious, are ‘only’ $125/hr vs $175 at my local Wahlberg rv. I guess that’s something. And same day gives me some peace of mind as I hate the ambiguity of waiting for service.   Even there, they replace the entire unit. No cheap boiler only fixes, I guess. 

    As to how it cracked, I think the p.o. was uncertain of what they were doing. They swear they followed procedure, ‘opened the yellow valves too’  yet I found about 7 gallons of water in the fresh tank when I started to dump the winterized lines. That makes no sense to have winterized and have that much water in the fresh tank if they opened the hot, cold and fresh valves underneath, as typical. Guess it’s possible that they only added antifreeze and didn’t blow out the lines. Doesn’t the winterize setting bypass the boiler?

    So I guess I’ll never know. A decent rv inspection would likely have caught this, so shame on me. I figured how bad could a once used 2023 trailer be stored over one winter. I’m now smarter after what will be an expensive lesson. 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • RobermcmRobermcm Member Posts: 34

    Just had a thought of how the boiler could have cracked. But I need nautilus valve experts to weigh in. 

    The water tank overwintered with about 7 gallons in it. Why it wasn’t dumped at winterizing was probably due to an oversight. If the valves had been in a setting that connected the fresh water tank to the boiler, could enough water have made its way down hill into the boiler to be a risk when it got cold?

    When I bought the unit, the Nautilus valves were in the configuration pictured - city water. In that setting, no tank water could get to the boiler. Correct?
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • berggerbergger Moderator Posts: 976
    It looks like it was in "power fill tank" mode.  This mode directs the water flow from the water hose connection directly into the water tank.  No water will flow into the interior water lines or into the Alde water tank.  It replaces the gravity fill that most trailers have.  If this is the setting the trailer was in when you bought it then I'm betting the previous owner also did not winterize properly.   Winterizing does bypass the Alde but they obviously did something wrong.  Possibly they did not drain the Alde at all.  However there is still a chance it was just a defect in the tank and the previous owner winterized correctly.  But the position of the valves on the Nautilus has me suspect of this. 

    Have you pressurized the system to see if there are any leaks in the plumbing lines/connections?  If so and there are no other leaks then most likely the lines were drained and filled with antifreeze but the Alde tank was not drained and thus cracked when the water in it froze.  If you have additional leaks in the plumbing then the lines were not drained and filled with antifreeze properly either.  I live in a place with 7-8 months of winter and or below freezing temps.  If the trailer is winterized properly with draining tanks/lines and then using a good antifreeze the Alde and plumbing lines will be fine.  I have my 400 winterized for 7 or more months a year and so far nothing has broken.  Hopefully this year will have the same results. 

    Let us know what Truma/Alde finds out when you take it to them. 
    2021 T@b 400 BD  "Vixen Gail" 
    2018 Nissan Titan Pro 4X "Big Bird"
    Leadville Colorado
  • RobermcmRobermcm Member Posts: 34
    bergger said:
    It looks like it was in "power fill tank" mode.  This mode directs the water flow from the water hose connection directly into the water tank.  No water will flow into the interior water lines or into the Alde water tank.  It replaces the gravity fill that most trailers have.  If this is the setting the trailer was in when you bought it then I'm betting the previous owner also did not winterize properly.   Winterizing does bypass the Alde but they obviously did something wrong.  Possibly they did not drain the Alde at all.  However there is still a chance it was just a defect in the tank and the previous owner winterized correctly.  But the position of the valves on the Nautilus has me suspect of this. 

    Have you pressurized the system to see if there are any leaks in the plumbing lines/connections?  If so and there are no other leaks then most likely the lines were drained and filled with antifreeze but the Alde tank was not drained and thus cracked when the water in it froze.  If you have additional leaks in the plumbing then the lines were not drained and filled with antifreeze properly either.  I live in a place with 7-8 months of winter and or below freezing temps.  If the trailer is winterized properly with draining tanks/lines and then using a good antifreeze the Alde and plumbing lines will be fine.  I have my 400 winterized for 7 or more months a year and so far nothing has broken.  Hopefully this year will have the same results. 

    Let us know what Truma/Alde finds out when you take it to them. 
    Thanks for those thoughts. How would you recommend pressurizing?  Set to City water with regulated hose attached?
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • BridgerSunsetBridgerSunset Member Posts: 86
    Regarding your question, and adding to @bergger 's comments:

    If the FW tank is mounted under the floor, at a level below the Alde boiler, I can't imagine how any water left in the FW tank could flow upward, against gravity, without the aid of a pump.  This, even if valves were at that time in a "dry camping" position connecting it ultimately to the boiler.

    Secondly, it seems there could be a scenario where water from the plumbing lines & fixtures throughout (that never got completely displaced by antifreeze) could roll back down and accumulate in the boiler.    < Not sure if there are any check valves in the water piping that might prevent backflow >.     The 3020 model Alde boiler, I believe, holds about 2.2 gallons - not sure what the 2023 year model holds.  The entire plumbing lines capacity (without the Alde boiler) volume is near that volume.  So if water did roll back and completely filled the boiler and left zero room for expansion during freezing, that would imply there was somehow a lot of water inadvertantly left in the plumbing lines.  

    Just a thought anyway.  Hope you get good news on repair.
    2021 T@B 400 Boondock  - Chev Silverado 3500HD 6.6L - Toyota 4Runner 4.0L
    SW Montana USA


  • pthomas745pthomas745 Moderator Posts: 3,641
    I think the Alde boiler would have to be completely full...stuffed...for it to be able to freeze enough to crack a stainless steel tank.  If there was that much water in the trailer, or so poorly winterized, there will be other damage in valves in the trailer: fresh water tank drain, various Nautilus valves directly behind the Nautilus panel, etc.
    2017 Outback
    Towed by 2014 Touareg TDi
  • RobermcmRobermcm Member Posts: 34
    I think the Alde boiler would have to be completely full...stuffed...for it to be able to freeze enough to crack a stainless steel tank.  If there was that much water in the trailer, or so poorly winterized, there will be other damage in valves in the trailer: fresh water tank drain, various Nautilus valves directly behind the Nautilus panel, etc.
    I so hope you’re wrong. I have glycol in my water lines, so it’s cracked somewhere. 

    Regarding the rest of the system, I plan to see if I can pressurize on the city water setting today, with the Alde bypass set to avoid air pressing into the glycol loop. I tried it yesterday and it wouldn’t hold pressure and I heard Alde gurgling. Presuming I had the valves set right (per picture minus red valve, not too hard) isn’t there a one way valve that should prevent that?  Like air was going into the boiler the wrong way. Low pressure too - bicycle pump and schraeder blow out. 

    Seaprately, maybe winterization was okay, but maybe the ‘air space’ creation process, if not followed, also crack the tank? 
    2023 Tab 400
    2015 Audi Q7 TDI
    Northern Ohio

  • pthomas745pthomas745 Moderator Posts: 3,641
    There have been several "cracked" Alde tanks with no relation to winterizing.  The Alde "air cushion" is really only a factor with the trailer using the fresh water tank and the pump for more than 10 days in a row or so.
    (Another confusing Alde thing they don't bother to explain.)
    So, I would wait and see. 
    For your pressure check, don't forget the low point drains and the faucets.


    2017 Outback
    Towed by 2014 Touareg TDi
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