Renew Alde air cushion

Bill&Suze

The Alde owner's manual advises renewing the air cushion after 10 days of use by opening the safety/drain valve for a few seconds. It goes on further to advise emptying the hot water tank after 10 days of use to form a new air cushion. I've read topics related to the air cushion on the forum but don't recall anyone specifically discussing doing this after 10 days of use. Is this a standard procedure for many of you long time contributors?

To empty the hot water tank, I am guessing that the valve and small white port labeled Hot Water Drain just below the Cold Water Drain aft of the driver's side wheel is the appropriate valve to open to empty the hot water tank. Once emptied, should it be refilled from the fresh water tank using the pump or by connecting to city water? Is either method suitable? 

Sharon_is_SAM

To drain the Alde water tank, use the yellow Alde Safety/Drain valve under the bench.  That valve is in line with the cold water low point drain which you can also use.  The cold low point drain will drain all the cold water supply lines.

Most of us empty our Alde and fresh water tanks and drain the plumbing lines after a trip to prevent any overgrowth of bacteria.  We do not travel with water in our tanks, so, before relocating on a trip, we empty.  

Regarding the air cushion, I think allowing some air into the tank by draining some water (holding the yellow valve) is adequate.

BandB

We attended the uCamp24 session with a Truma Alde representative. This is what he said:
When re-establishing the air cushion it doesn't matter if the Alde system is off or on.
1. Turn off city water or the pump (if dry camping) so there's no water pressure.
2.  Open a hot water faucet and leave it open.
3.  Open the yellow valve for a few minutes (the longer the better) to let water drain out.
4.  Return the yellow valve to the horizontal position. 5.  Close water faucet.
6.  Turn water back on. Open a hot water faucet. If it hisses and pops (pushing out air until water flows smoothly) you've done it correctly.
He said to do this every 7-10 days of camping. If out for months do it every 5 days.

It shouldn't matter which method you use to refill the tank. Either City Water or using the pump.

Bayliss

Interesting info, @BandB.  I have always found the Alde Manual instructions for creating an air cushion to be contradictory.  Regarding the "Air Cushion." the manual says you create the air cushion by opening the safety drain valve "for a few seconds" every 10 days.  BUT, in a separate "NOTICE" immediately below that instruction, there is a contradictory advisement, which states that the tank "should be emptied approximately once a week" to help ensure a new air cushion is formed.

Thus, the question for me has been, which is accurate?  Release some pressure for "a few seconds," or "empty the tank" every 10 days?

I have always followed what I refer to as the "10 in 10" rule..............that is, open the safety drain valve for 10 seconds, every 10 days.  That has worked well for me, without any issues.  It seems like a logical way to create the air cushion, particularly because the cushion is "at the top of the tank."

The instructions you received at üCamp sound like a combination of those for creating an air cushion and emptying the hot water tank.  I also find it interesting that the Alde rep apparently said it does not matter if the system is "on" or "off" when creating the air cushion.  I say that, because their manual includes a "WARNING," which specifically advises to never open the safety drain valve while the system "is under water pressure and/or still warm."

Finally, I recall that @pthomas745 wrote the following (back in August 2022), which may be the explanation for the discrepancies, although it is not clear from the Alde manual:

Check the manual again: the section about the air cushion says maintain the air cushion after 10 days of use, not "non-use."  And, then the "Notice" says to "drain the Alde Tank after 10 days of use".   (On the various Alde web sites and videos, this is described as "continuous" use.  There is no description of the need to do it if you are just "occasionally" using the Alde hot water.  (Alde Safety/drain valve Questions (vanillacommunity.com)

Binghi

BandB said:

We attended the uCamp24 session with a Truma Alde representative. This is what he said:
When re-establishing the air cushion it doesn't matter if the Alde system is off or on.
1. Turn off city water or the pump (if dry camping) so there's no water pressure.
2.  Open a hot water faucet and leave it open.
3.  Open the yellow valve for a few minutes (the longer the better) to let water drain out.
4.  Return the yellow valve to the horizontal position. 5.  Close water faucet.
6.  Turn water back on. Open a hot water faucet. If it hisses and pops (pushing out air until water flows smoothly) you've done it correctly.
He said to do this every 7-10 days of camping. If out for months do it every 5 days.

It shouldn't matter which method you use to refill the tank. Either City Water or using the pump.

The Truma session implies:

1). The air cushion issue applies only to the Alde hot water tank and the trailer’s hot water lines.

2). The only yellow valve you need to open to produce the air cushion is the one on the hot water line; you don’t need to open the yellow valve on the cold water line.

So far so good, I guess. Where I get off the Truma train: doing this every 5-10 days on a road trip. On a 6-8 week trip I typically do it once. And to be honest, I haven’t followed the intricate procedure prescribed by the Truma sales rep - I just open the valve for about 15-20 seconds. I never have drained the tank to establish an air cushion.

Sharon_is_SAM

There is only 1 yellow valve on the 320 and it is inline with the cold water supply/drain line.  I believe the 400 has 2 yellow valves - 1 for the Alde and 1 for the Flow.  There is no yellow valve on the hot water line.

RTWCTS

Binghi said:

So far so good, I guess. Where I get off the Truma train: doing this every 5-10 days on a road trip. On a 6-8 week trip I typically do it once. And to be honest, I haven’t followed the intricate procedure prescribed by the Truma sales rep - I just open the valve for about 15-20 seconds. I never have drained the tank to establish an air cushion.

We were camped near a couple from Columbus, OH at uCamp that told us about not following the air cushion procedure on their 400. The Alde flow unit eventually cracked. It was a $2000+ repair. We attended the same Truma tech session as @BandB... and took good notes too.

Binghi

Sharon_is_SAM said:

There is only 1 yellow valve on the 320 and it is inline with the cold water supply/drain line.  I believe the 400 has 2 yellow valves - 1 for the Alde and 1 for the Flow.  There is no yellow valve on the hot water line.

Aha! Thanks for the correction. i’ll keep doing both yellow valves.

Bill&Suze

The Truma Alde rep that Binghi quoted didn't specifically say to open both yellow valves but it sounds like it is advisable based on RTWCTS' comment about the Alde Flow cracking. Two valves better than one.

BandB

After uCamp24 we had our glycol flushed at the Truma shop in Elkhart, Indiana. We learned that emptying the hot water tank as part of establishing an air cushion flushes out sediment that may collect in the tank. We also learned it's important to have an in-line water filter between the campsite faucet and the camper to remove any water contamination (like iron, etc.) and protect the Alde system. We had one but didn't use it, thinking our Berkey Go was all we needed for our drinking water. 

Bill&Suze

Sharon_is_SAM said:

To drain the Alde water tank, use the yellow Alde Safety/Drain valve under the bench.  That valve is in line with the cold water low point drain which you can also use.  The cold low point drain will drain all the cold water supply lines.

Most of us empty our Alde and fresh water tanks and drain the plumbing lines after a trip to prevent any overgrowth of bacteria.  We do not travel with water in our tanks, so, before relocating on a trip, we empty.  

Regarding the air cushion, I think allowing some air into the tank by draining some water (holding the yellow valve) is adequate.

I just want to be clear on what Sharon is SAM said regarding draining tanks. Obviously there is a benefit in having less weight to haul around while traveling. Are you emptying all tanks - fresh water, cold water and hot water? In another topic it was said that the Alde reservoir will also drain when the cold water tank is drained. This would only apply if you plan to move on to another location that provides city water. If dry camping, you leave a certain amount of water in the fresh water tank. Am I understanding this correctly?

dsfdogs

@Bill&Suze I think we all travel differently. Personally, I always travel with a full fresh tank. I've tried it both ways on both a 320S and 400 and I like the feel of a full tank.
The cold low point drain will also drain the main Alde tank, but not the Flow tank. (Not sure if you have one). The yellow flapper would need to be raised to drain that. At the end of a trip, I drain everything.

Sharon_is_SAM

@Bill&Suze - we often go from dry camping to a site with available water, so, we dump our fresh water tank and either fill up at the camp site or hook up to city water.  In this scenario, no need to empty the Alde hot water tank or to drain the plumbing using the low point drains as we will be using them at the next campsite.  

When we leave to return home, we empty the fresh tank and the Alde tank.  At home we complete the remainder of draining the plumbing lines before storing.

We have traveled long distances from Ohio to the Southwest and we do not camp when in transit, so, our water management may be different compared to someone who camps along the way.  Hope this helps.

Mickerly

However the water gets into your trailer, into the fresh tank or pressurized from the campgrounds, it will carry some dirt. More if the campground is on a well. It is prudent to use some kind of filter when putting any water in the trailer.

Stagnant water will begin to grow, especially inside the trailer's water lines and fresh tank. It is both prudent and recommended to drain the water system when the trailer is not actively in use. Allowing the water to remain in the trailer for extended periods of time will cause bad things.

Pre-Nautilus trailers empty the hot water tank through the normal water drains or the Alde pressure relief valve. Post-Nautilus trailers drain the hot water tank through the Alde pressure relief valve only.

As a technique, we close all valves, faucets and pressurize the water system the morning before getting on the road. We carry 1/3 tank of fresh water. If we decide to stop before the destination, everything will work. On the way home, we open all the drains, the bath faucet, and the kitchen faucet. We leave everything open until the next trip. Airflow and dry lines will keep the system clean. We are rarely gone more than 5 days. Refilling the system for the next trip will establish the airspace for hot water expansion when the Alde is turned ON. Note: the airspace is only needed when the Alde is ON.

Bill&Suze

@Sharon_is_SAM and @Mickerly, thank you both for those insights. It's very helpful to hear what long time campers have found to be best practices while traveling. I think a water filter would be prudent. Any suggestions?

Sharon_is_SAM

 Camco Taste Pure - Amazon or Walmart.

Sharon_is_SAM

Sickerly said:

“Pre-Nautilus trailers empty the hot water tank through the normal water drains or the Alde pressure relief valve. Post-Nautilus trailers drain the hot water tank through the Alde pressure relief valve only.”

This is important to note.  Those with the Nautilus must use the yellow valve under the seat!  

Bill&Suze

Sharon_is_SAM said:

Sickerly said:

“Pre-Nautilus trailers empty the hot water tank through the normal water drains or the Alde pressure relief valve. Post-Nautilus trailers drain the hot water tank through the Alde pressure relief valve only.”

This is important to note.  Those with the Nautilus must use the yellow valve under the seat!  

The photo below shows various drain ports for the 2024 T@B 400 Boondock. These are located on the driver's side on the frame just behind the wheel. I've experimented with draining the fresh water tank successfully but have not opened either the cold or hot water drain valves. Is it likely that the hot water valve does the same thing as the yellow valve under the seat, and either one will drain the Alde?

dsfdogs

@Bill&Suze in my experience with my '23, when I open both those low point drains, it also drains my main Alde tank, but I have to lift the yellow flappers inside to drain the flow tank. Go ahead and experiment!

Bill&Suze

Thank you @dsfdogs, that's helpful. I'm glad you mentioned that you lift the yellow flappers (plural) because I also have two, one obviously to drain the Flow.

Bill&Suze

I posted the photo just above showing three drain points. Draining the fresh water and hot water tanks is clear to me but can someone please clarify what is drained by way of the cold water drain port?

Sharon_is_SAM

The cold water plumbing supply lines to the toilet, sinks, showers and Alde all drain via the cold water low point drain.  The hot water supply lines are drained via the hot water low point drain.  And in the Nautilus models, the Alde is drained via the yellow valve.  

Bill&Suze

Sharon_is_SAM said:

The cold water plumbing supply lines to the toilet, sinks, showers and Alde all drain via the cold water low point drain.  The hot water supply lines are drained via the hot water low point drain.  And in the Nautilus models, the Alde is drained via the yellow valve.  

Thanks yet again. I may be mistaken, but I've seen no discussion of these particulars in the Owner's Manual yet. Out of curiosity I think I'll open the cold and hot water drain valves just to get an idea of how much water is retained in those plumbing lines. I'll leave the Alde alone.

Sharon_is_SAM

Try opening a faucet when you drain the plumbing or Alde.  It stops any vacuum by letting air into the system.  

I think most RV manuals are not designed for the novice owner.  There is the assumption that you are familiar with the basics of how a camper operates.  The forum and other RV education sites are invaluable in that regard.

Check out ScottGs Plumbing Schematic here.  It is helpful to understand the plumbing.  Of course, this is pre-Nautilus, but the layout is the same.  If you check further down in the link, I believe there are some owner-made Nautilus system schematics, too.
https://tab-rv.vanillacommunity.com/discussion/7856/plumbing-resources#latest

Mickerly

The Nautilus draining issues are caused by the lines going up to the Nautilus panel. They no longer lay flat on the floor. It is possible it may siphon through to either the cold or more probably hot water drain.

To figure it out, pressurize the trailer with water. Disconnect the water source. Open the low point drains. When it stops draining, open the yellow pressure relief valve. See if water comes out the Alde drain. It will not come from the low point drains.

My trailer is pre-Nautilus. For the Nautilus, I only know what I have read. 

Da_Birds

This has been something I've been trying to figure out since we purchased our '21 320-CS (with Nautilus). We have never been camping for more then 7 days and drain everything at the end of each trip. So renewing the air cushion while in use is not an issue. But I want to ensure it is being stored properly when not in use.

At first I would drain the Alde tank using the yellow valve. However, I found that if I opened the low point drains first I would get a release of pressure and the hot water tank appears to drain. At this point the yellow pressure relief valve did nothing when opened (no release of water or pressure). If I opened the the yellow valve first It would release pressure and hot water but then when opening the low point drains I would not get the same release of pressure and hot water.

It seems to me, at least on my model, opening the yellow pressure release valve is redundant after you open the low point drain. It seems opening the low point drains accomplishes the same thing (releasing the hot water tank pressure and draining the tank). I still make it a habit of opening the yellow valve inside the cabin after each trip but I just feel it's pointless. Not a major hassle but it would be nice to know for sure if this is really necessary or not.

Mickerly

So it does siphon over the hill of the Nautilus. I'm glad there is confirmation of reality.

BillCB

Where is the yellow valve inside the cabin? I don't see one in my 400.

RTWCTS

BillCB said:

Where is the yellow valve inside the cabin? I don't see one in my 400.

There are two of them in a 400. They are located in the compartment under the bed on the driver’s side. You’ll need to unscrew the bed panel and lift it up to find them. 

Like some others, we now leave the screws out of that panel because we are regularly in that compartment to do this procedure. I also drilled a finger hole in the panel to make it easier to lift.

Maxcamp

I find the need for playing with this valve bewildering. 
Commercial and residential hydronic systems- whether heating or domestic hot water- by code must have devices or copper loops to accommodate thermal expansion.  How is it Nucamp failed to do this on a 40K machine?

As I understand it, the glycol loop expands back into the glycol tank behind the toilet.
The hot water loop has nowhere to go?

If H20 density decreases from roughly 62pcf at STP to 60 pcf at 195F and we have a 2.1 gallon tank plus line, the ~3%  to 4% expansion creates how much pressure increase?   Unless that drives the psi in the system far above 40 psi I would not be concerned.

Here is one example of a device that would probably obviate all this angst and tunneling under the bed...
https://supplyonline.com/rectorseal-exptmini-thermal-expansion-tank-w-1-2-in-mip-ss-connection.html
along with a valve
https://www.zurn.com/products/water-control/thermal-expansion/model-bvecxl

Please don't rush out and buy these, I'm just speculating.

BillCB

RTWCTS said:

BillCB said:

Where is the yellow valve inside the cabin? I don't see one in my 400.

There are two of them in a 400. They are located in the compartment under the bed on the driver’s side. You’ll need to unscrew the bed panel and lift it up to find them. 

Like some others, we now leave the screws out of that panel because we are regularly in that compartment to do this procedure. I also drilled a finger hole in the panel to make it easier to lift.

Many thanks!
Bill