Hot water problems - Thermostatic Mixing Valve - 2021 Tab 400

Pymbur

I know this be has been discussed numerous times before, but I’m looking to start a thread specifically for the 2021 models. I’ve read as many other threads as I can find, but the solutions don’t seem to match up for my 2021. At least not what I’ve been able to find. 

I have hot water in the kitchen sink and bathroom sink. 

My shower hot water is scalding hot for 5 seconds, then straight to frigid cold.  

My mixing valve is turned as far as it can go.
I’ve seen the other threads here about removing a screw etc etc, but my mixing valve doesn’t look like the ones in those posts. 

Bayliss

@Pymbur, I don't have the new Speedfit "Thermostatic Mixing Valve" (TMV), but if you have not already read it, start with this discussion thread:

https://tab-rv.vanillacommunity.com/discussion/comment/159795#Comment_159795

Also, I copied the below info from an earlier post regarding adjusting the TMV.  It was posted by @pthomas745, but he pulled it from the T@B Facebook group, so if he has anything to add, he will likely chime in:

Message from nuCamp: 

We are just checking to see if you were able to resolve this issue.

If not, please try the following:  Remove the red cap from the mixing valve, turn it upside down and use it as an adjustment tool.

Turn the spindle clockwise to lower the mixed water temperature.

Turn the spindle counterclockwise to raise the temperature.

If you need any additional information, please contact our Customer Service department at 844-823-9112 EXT 834.  We hope that helps!

Link to the Alde page:

https://www.alde.us/news/new-product-alde-speedfit-mixing-valve/

pthomas745

Nothing to add from what is already in that thread.  I know that photo is hard to read.  Maybe this link to a .pdf will be more readable? 

https://us.v-cdn.net/5021717/uploads/editor/rr/lkx1oroankfh.pdf

Sharon_is_SAM

@Pymbur - please check your Alde Flow pump.  Both the Alde pump and Flow pump should have the same settings - 2 or 3.  Do not try to adjust them from the display as that function is not engaged.  After you do this, wait an hour, then check it.  Also restore the air cushion in both the Alde and Flow tanks by briefly depressing the Safety/Drain valves.  Please let us know what happens.

Denny16

It is possible the mixing valve might be defective?  The OP is getting Luke warm water to scalding hot. This sounds like the vale is not consistently mixing the cold and hot water together.

Cheers

backpacker47

2021 TaB400. Experiencing the same issues! However, after a lot of reading here and FB I think we have fixed it. My observations of your situation Pymbur are: The Thermostatic Mixing Valve (TMV) is designed to shut off if the hot water passing through it is too hot. The key take away here is "passing through it". Hence scalding hot water then 100% cold supply as the hot is shut off. The same should thing should happen at the bath and kitchen tap too. Try running each for a bit longer to give the TMV a chance to react. If the water does suddenly go cold then the valve seems to be working properly. Secondly, from your pic. it looks like the adjusting screw on the TMV is out too far, I had the same problem with being unable to balance my hot water temp. at the taps. Here's what I did and it seems to have fixed it. Shut everything off, screw in the adjusting screw on the TMV until it is about 1 thread above its collar (the bibber nut in the housing) On the control panel, set the hot water to "Normal" (i.e. half the triangle filled in). Set the electric to 1 KW. Make sure the LP is off. Now go to the "Service" screen which shows the temperature of the Glycol and the Hot Water. At the above settings they should, eventually, read between 120 and 125 F. Be patient, it can take 20 - 30 minutes. Now, using a calibrated thermometer (meat therm. works fine) run the hot only at the sink. It will run cold/cool then quite hot for a few seconds but should then stabilize. Ideally you want this to be about 41C - 42C / 104-107F. Too hot and you will risk scalding and run out of hot water quickly. Adjust the screw on the TMV as per the instructions in the info. sheet that should have come with it. Repeat the process a few times, keeping an eye on the water temperature in the boiler via the control panel. If the water temperature in the tank drops below the required temperature at the tap, then wait until it heats up to at least 118F.  The bathroom should then also be OK by default. Bear in mind that the hot water boiler is not very big so it is easy to run out of hot water and think there is a problem with the TMV. One thing that is not highlighted is that this is NOT the same as your household system The hot water at the tap should be at a useable temperature, WITHOUT adding cold water. Of course these are just my observations, I could be wrong!

Denny16

Nice summary of the system.  Thanks.
cheers

Sharon_is_SAM

@Pymbur - how did you resolve this?

Disenchanted

I have gone from loving my 2021Tab 400 to baeelyliking it.  On my current trip, the batteries have failed due to overcharging, and y thermos mixing valve will not deliver Hot water insistently no matterhowiadjust it, even after following the great advice above.  My Aldiworks fine and is making hot water, but if I turn on the pump, cold water overpowers the hot.  My nautilis valves are set correctly for dry camping, if I leave the pump off hot water makes it to the sinks and shower but as soon as I turn the pump on it all goes cold, even with TMV set to one or 2 or 3 turns open.

Tomorrow I will stop in Flagstaff for a new battery, but if I spend a good chunk of each trip troubleshooting unreliable NuCamp complexities, the allure of the Tab fades fast.

Any new ideas on the TMV or should I replace it when I get home?  Anyone else destroy a battery due to overcharging when hooked to shore power?

Thanks in advance, Disenchanted Tab 400 owner

MuttonChops

@Disenchanted ; Hopefully you are just enduring initial use issues/part failures.  As when the Adle is working well (which is most of the time) it is a wonderful cabin and water heat source.

I find the Mixing Valve difficult to adjust as the process and instructions are confusing.  Carefully revisiting the 'how to adjust' instructions in the manual might help.

And of course like at home you need to wait for the 'older cold' water to clear the lines before getting hot water, taking Sea-Showers as I do means more time for the lines to cool & more cold water shocks.  The Alde tank is limited to ~two gallons and even with the 400's extended hot water feature you might be demanding more hot water than available.

Some owners (few and far between) have reported defective Mixing Values from the factory.
You can also disassemble the mixing value to replace internal parts or confirm everything is normal.

As for the Battery being damaged from over-charging.  You maybe first to report that.  It would be a very rare situation . . . are you confident overcharging is the cause?
Is the WFCO power center set to the correct Battery type AGM/Lithium ?
If Lithium, those batteries have an internal Power Management System . . perhaps you have a Bad from Factory battery.

Does sound as if a Service Department conversation if not visit would be helpful.

Sharon_is_SAM

@Disenchanted - I believe you have the Thermostatic Mixing Valve.  It sounds like you have followed the above advice from backpacker47.  It is very frustrating when you simply want hot water.  You mentioned that you get hot water at your sink and shower, but the water pump prevents hot water.  So, does that mean you are you getting hot water when you are hooked up to city water?  Just to make sure, are you disconnected from city water when you run the pump?  

Also, please start a new thread regarding your battery.  There have been known cases of premature battery failures with the Harris batteries.

Disenchanted

@Muttonchops - great diagram... can you provide a link to the source... or tell me what 2 and 3 are? Thanks, i'll try to take this apart today.  

@Sharon_is_SAM - I was boondocking, nautilus in dry camping alignment.  After all adjustments failed me, i experimented.  IF i turned off the pump and just used residual pressure, with the faucet in the hot water position, the water would turn warm at the faucet.  Then i would shut the faucet, run the pump until it stopped (build up system pressure), turn the pump off and open the faucet again.  Using that method:
a.  I could confirm the alde readings... there was hot water
b. I could eek out enough hot water to wash my face or with repeated cycles get a warm sea-shower.

but if i left the pump running, the cold water seemed to overpower the hot water at the mixing valve and only pass cold water.  

It worked fine for my first two seasons of camping, but has eluded me this season.  I plan to replace the TMV and see if that fixes the problem.  

THANKS to all for your input

MuttonChops

Disenchanted said:
- - -  great diagram... can you provide a link to the source...

Diagram is from the LK 550 AquaMix mixing valve literature (attached).

The LK 550 was noted by at least one forum member has the make/model used in their system.

Disenchanted

Update:  I took my TMV out of the trailer - the John Guest Push Fit connectors are actually pretty easy to undo - press the black elbow and white collet into the TMV, hold the collet against the brass and pull the fitting (elbow) out.  Worked for all three joints.

Took the valve apart on my workbench. Found a crushed o-ring, and the hot water check valve seemed stuck so i removed the screen and exercised it several times... and put it all back together... It now works like it is supposed to, but the water temp never goes above lukewarm, but it stays at lukewarm with the pump running!! i could live with that, but wife likes hotter water so going to buy and install a new valve since it is so easy to install.  A couple pics below... Oddly, my best support came from an Airstream dealer - Airstreams have Alde units too.  My Nucamp dealer was useless, had no parts in stock, and advised it was very hard to order parts from Nucamp.  The Airstream dealer placed the order for the new TMV while i was on the phone.  If you are ever in a pinch it is useful to know that airstreams have alde units and parts too. 
Unit disconnected at the John Guest Push Fittings:
 
Parts (disassemble with 3/4 inch wrench) top row is from main body, lower row is from the hot side connector (collet with sharkbite teeth, o-ring, screen retainer, screen) Also pictured is the crushed o-ring

Reassembled valve with new o-ring

MuttonChops

Disenchanted said:
. . . Took the valve apart on my workbench. Found a crushed o-ring, and the hot water check valve seemed stuck so i removed the screen and exercised it several times...

Excellent!  Looks like you have found the 'root cause'.
Now, is your mixing valve an LK 550 ?  - - -  pictures look like a different brand/model then used in earlier build-year Tabs - - -

Disenchanted said:
. . . Oddly, my best support came from an Airstream dealer - Airstreams have Alde units too.  My Nucamp dealer was useless, had no parts in stock .  . .

Not the first time someone has made that observation.  Which is interesting since nearly all nüCamp units have the Adle while Airstream currently only has One Model of their large selection that uses the Adle.

Perhaps it is due to Airstream dealerships being Airstream only.  While nüCamp dealers are just your average multiple RV Brand sales lot.

I was looking at the Airstream Basecamps recently and was impressed with the knowledge and helpfulness of the dealership's Service Department . . . not a typical multiple brand dealer professionalism. (of course Airstream has all the same, everyday quality & materials issues of the NA RV industry)

MuttonChops

Disenchanted said:
. . . the John Guest Push Fit connectors are actually pretty easy to undo - press the black elbow and white collet into the TMV, hold the collet against the brass and pull the fitting (elbow) out.  Worked for all three joints.

Thanks, I did not know 'the name' for those things.

For others (like myself) here's a video on how they work:

Demo is at timestamp 1:09 'ish

   John Guest Push Fitting Video

Sharon_is_SAM

@MuttonChops - disenchanted has a 2021 400 with the newer style mixing valve that replaced the LK 550 valves in our older rigs.
@Disenchanted - please update us regarding the hot water situation once you get the new TMV installed.  It really adds to our knowledge base when hot water issues arise.  I believe you were the first to report inadequate hot water when the pump was used.  When this is all repaired, I hope you can change your ID to Enchanted instead of Disenchanted😊

Disenchanted

@Sharon_is_SAM Ha Ha... overall, we love our T@B... just wish the dealer and manufacture support was better, and there were not so many "surprise" issues at inopportune moments.  These forums do help us all be self sufficient and enable us to self service our amazing little rigs to overcome the dealer/manufacturer support gap.  Should get my new TMV from the Airstream dealer in about 2 weeks and will update then.  

Philipddean

Any Update?  I am having a similar problem.  No way to get hot water without using the boost...  Every indication is the water is hot going to the mixing valve.  It is full hot and still no hot water without the boost.

pthomas745

@Philipddean the year and model of your trailer will help.

Have you adjusted your mixing valve?  Are all of your winterizing valves in the proper "camping season" position?  The bypass valve, etc.  (This is a year/model specific sort of question).

Checked the outdoor shower faucets to make sure they are off?  The outdoor shower head off, too?

The good news is you are getting hot water, just not "hot enough" on the non-boost setting.

In the Alde service menu, have you looked at the water temperature readout there with the Alde in the "normal" hot water and the "extra/boosted" hot water positions?

Philipddean

pthomas745 Yes, I have done all the things you mentioned.  2022 Tab 400.  I get the same result whether Boondocking or city water.  I will order a new valve when I return home from this trip in about a month. Hopefully that will solve the problem!

Disenchanted

I resolved my issue by purchasing a new TMV from the local Airstream dealer, installed it, and hot water functionality returned to normal.  The issue i was having with lack of hot water, appears to have been due to a faulty TMV

Sharon_is_SAM

Thanks for the update @Disenchanted.

Philipddean

I am back and have finally figured out my hot water problem!

We left a couple weeks ago for a 6-week trip.  I thought the problem may have magically fixed itself....not so.

I tried everything to get hot water. We have a 2022 TAB400.  Here is what I did:

1: Made sure the mix valve is full hot.

2: Confirmed that the hot water pipe is connected to the correct side of the mix valve.

3: Made sure the outdoor shower water valves are turned off.

4. Made sure all the air is out of the system.

5. I have tried both water from the tank using the pump and city water.
6. Made sure the one-way check valve prior to the mix valve is correctly installed.

What we got was a short(2 second) burst of hot water and then cold.  We have tried boosting, but it doesn't seem to help.  Boosting did seem to make a difference last year.

Glycol temp is 156 and water temp is 149. It was higher when boosting.

I contacted NuCamp and got the TMV part number and then Moix RV in Conway, Arkansas which was along our planned route.  Mason at Moix RV was a great help and had the mix valve overnighted to our next stop from the factory.

30 minutes after receiving the part, we have hot water!!  Awesome.  I think the valve may have never functioned correctly, but no way to be sure.  I am just thankful to NuCamp and Moix for all their help in resolving this problem!!