2021 T@B 400 Water issues. No water from hot side of faucet. Hot water from the cold faucets.

jacobyoconnor

Hi NuCampers. We are heading out on our maiden voyage with our new 400 tomorrow and while running through all the systems and testing the water I noticed I was only getting water out from the cold side of the faucet. (any of the faucets) When I got the water up to temp all the water coming out is hot even though it is the cold side. I opened up the alde bay and the blue lines are hot. I have gone through every possible setting and can't seem to get anything to work. Has anyone had this problem before? Any tips or is my system piped wrong? Why wouldn't I get water from the other lines?

dlb

Your dealer should have checked all the systems.  Call them and explain what you have found.

I suspect someone has not installed the water lines correctly.

manyman297

Is your water pump pressurizing when you run the cold water?

jacobyoconnor

yeah, I think so. I wish there was a photo or diagram of the proper routing of all the plumbing. I can't quite understand what could be done wrong if anything

Sharon_is_SAM

@jacobyoconnor - under the bunk on the driver side you will find the Alde and the mixing valve and I think the Nautilus.  Photos will help us help you.  To me it sounds like maybe a valve is stuck closed.  Or maybe a failed mixing valve?

Snoblett

@jacobyoconnor
was this ever resolved for you?
I have the exact same issue with my Tab 400 that I took delivery of in mid July 

When on City water , the hot water works just fine, but dry camping causes scalding hot water to back flow into my cold supply lines.

as of a couple weeks ago, tech support didn’t have a fix for me and my repair place doesn’t have an answer either 

Sharon_is_SAM

@Snoblett - I reviewed the Nautilus diagrams provided by @MuttonChops - https://tab-rv.vanillacommunity.com/discussion/14652/nautilus-p3-flow-diagram#latest specifically the dry camping setting.  There is no check valve on the cold water inlet of the Alde and coupled with the air inlet at the Alde water outlet, it appears that the Alde can backflow under the right conditions.  The pump running continuously is typically due to a leak or obstruction on the inlet side of the pump.  If there was even a partial obstruction from tank debris, that may be enough to cause a preferential draw from the Alde.  Just curious, while set to dry camp, what happens if you bypass the Alde?  Does the pump still run continuously?  

The other thing I thought about is a partial obstruction at the blue valve.  If the valve only opened partially, is it possible that “city water” provides enough pressure to overcome the resistance, but the pump is up against too much pressure?  

There has been many incidents of tank debris.  Have you checked the pump filter?  

Snoblett

@Sharon_is_SAM
thanks-  there isn’t any debris that I’m aware of on the pump filter, at least not that I can see through the clear plastic.

The idea of performing a test of bypassing the Alde is an excellent idea.  I don’t have access to my tab right now to do so, but I’ll put it on the list of ways to isolate the problem.

something that did happen that is convoluting things is that a leak developed on the inlet side of the pump while I was going through and testing all the configurations earlier this month before winterizing it.   It became a substantial enough Lea that I had to keep a towel there fir the drips.  What I don’t know is if there had been a very, very small leak there the whole time that worsened, or if it is a new problem.

I had been checking for leaks regularly because the pump running continuously was an issue from day 1.   

I was too naive if a camper owner ti know it was a problem until I had already got it home to NY from Iowa where we bought it.

Sharon_is_SAM

When you eventually retrieve the 400, unscrew the plastic filter and remove the mesh cylinder to check for clogging.  

The leak on the inlet side of the pump may explain the pump running.  Did you identify where exactly it was leaking?

Snoblett

Sharon_is_SAM said:

When you eventually retrieve the 400, unscrew the plastic filter and remove the mesh cylinder to check for clogging.  

The leak on the inlet side of the pump may explain the pump running.  Did you identify where exactly it was leaking?

Sharon_is_SAM said:

When you eventually retrieve the 400, unscrew the plastic filter and remove the mesh cylinder to check for clogging.  

The leak on the inlet side of the pump may explain the pump running.  Did you identify where exactly it was leaking?

The leak was right at the crimp at the pump inlet where the white flexible tube comes in from the nautilus with the fresh water supply going into the pump.

Sharon_is_SAM

Easy to replace the inlet hose.  We replaced ours for the same leak.

Snoblett

Sharon_is_SAM said:

Easy to replace the inlet hose.  We replaced ours for the same leak.

I guess the crimp needed to be tightened- but I’ll keep that in mind if it leaks again.  Agreed, it would be an easy replacement 

Denny16

Grand, glad you got it sorted, and it was not a Nautilus valve issue, which, as shown on Sharon’s diagram, does not route hot water, just cold water.  

Unlike most residential water systems, the hot water output of the Alde does not go directly to the hot water pipes, but goes to a temp. conteol mixing valve, to reduce the hot water temp. to the hot water lines.  I think, when the water pump developed its loose connection on the suction side, it reduced the cold water pressure output (sucking air into the pump from the loose connection) and the cold water pressure drops.  With the cold water pressure reduced, the hot water pressure from the Alde being initially greater, perhaps causing the hot water mixing valve to allow hot water to back feed out the cold water lines for a minute or so.  This mixing valve,  is the only point hot and cold water lines are controlled by a single valve, except for the Alde Bypass vale, which could also allow a back feed of hot water to the cold water lines, if it was not working correctly.  

cheers

Sharon_is_SAM

@Denny - the hot water can back feed out the Alde tank cold water inlet.  I think @Snobletts issue can happen regardless of the mixing valve.  Once he can repair/replace the pump inlet hose and pressurize the pump we’ll know more.  

Here is more info from the Nautilus diagram thread that lends more evidence to the Alde back feed idea.   Snoblett said:

“This creates the situation where my hot water runs almost dry at the spigots and purely, hot scalding water is running through my cold lines into my cold spigots.  This includes the toilet.  Scalding hot water flushing the toilet.”

It doesn’t sound like It is getting to the mixing valve at all.

Denny16

Thanks Sharon, missed that, and this is an interesting issue, edited my previous post.
The diagram you posted, whilst a Nautilus flow chart, does not show the Hot/Cold mixing valve on the hot water side of the boiler.   There seems to be a combination of issues going on here with this problem of constant hot water flowing out the cold water taps.  I can only see several major causes, based on the diagram:
 1. Alde hot/cold water mixing valve allowing hot water back up cold water lines, with no mix of cold water (but this would also happen if connected to city water, so not the OP’s problem)
2. Alde bypass valve not completely seated or broken with a failed check vale, allowing hot water back into cold water line.
3. Water pump not getting full pressure ( due to poor connection on either side of the pump, creating less pressure on cold side, than pressure from Alde hot water tank, but this would equalize after a few minutes. 

This issue is a puzzler, and beyond my pay grade! 

Cheers 

Sharon_is_SAM

So, @Snoblett - the leaky pump was the culprit!

https://tab-rv.vanillacommunity.com/discussion/14652/nautilus-p3-flow-diagram#latest

Snoblett

@Sharon_is_SAM
Thank you for linking the the threads with the P3 flow diagrams.  I got lost and didn’t realize the threads had separated.  It’s all one big humbly mess in my head.  And, forgive me for not giving you credit as well when I stated the output confirmed as the lack of pressure maintained by the pump. 

This has been quite the puzzler.

Sharon_is_SAM

Glad you got it fixed!  We all learned something here.  I am looking forward to the response from nuCamp regarding the lack of check valve.  

Denny16

Yes Sharon, a check valve on the Alde cold water inlet would prevent hot water from backing up and out the cold water inlet.  That said, isn’t the cold water inlet at the top (highest) point of the hot water tank?  If so, wouldn’t this reduce the chance of a back feed of hot water from getting into the cold water pipe?

Cheers 

Snoblett

@Denny16
you are right that the pipe coming out of the Nautilus feeding the Alde Flow is at a high point on the nautilus.  This does not prevent back flow in the least.  I’m amazed at how quickly a loss of pressure just sucks it out of the Alde and back through the Nautilus maze.

Denny16

Yes @Snoblett, I see what yiu are referring to.  I was referring to the Alde Hot water tanks, but I see your point.  A check valve on the cold water line going into the Alde boiler would solve the issue.
cheers

Snoblett

@Denny16 ah, I re-read.  Right the inlet on the Alde is up high.  But it matters not.

Unless having a check valve would be somehow damaging to the system, I think NuCamp is obliged to have a check valve preventing the back flow.  

The water coming out of the Alde Flow is extremely hot.  The whole point of the Alde mixer is to prevent scalding, so it is known to be too hot out of the unit.

that’s my take, anyhow.

Snoblett

Folks, we may not be done with this thread.

I spoke with B&B Moulding today. They make the Nautilus.  I called them to inquire on an inline check valve that might be used at point F on the P3 manifold.   

When I described to them what is going on, they said they never had a customer describe their water behaving this way. 🤷🏻‍♀️

They are going to run some test scenarios in-house to try to replicate my situation.

In the meantime, they acknowledged that there may still be an internal flaw in my nautilus.  

They are sending me two parts.  For starters, I will put in an inline check valve at point F on the manifold.  If that doesn’t correct the problem, it may imply a faulty valve and they are sending me a blue/white dual valve assembly.   I really hope it doesn’t get to that point! 

I’ve requested that NuCamp and B&B engineering put their heads together on this.

I will post an update when I either test the check valve OR hear from the respective engineering departments.

Denny16

I think, this is just an educated guess, you have a faulty valve in the Nautilus unit.  Hope you can get this sorted.
Cheers

pthomas745

@snoblett Some pictures of all this would be great to have.  Sorry you have to go through this, but the advance of Tab Science will be very useful.

Snoblett

@pthomas745
yes, I will document along the way so others can benefit.  👍🏻

Snoblett

It was a beautiful 50° day in western NY today. I dewinterized my 2021 Tab 400 and installed the check valve provided by B&B Moulders.  This resolved my hot water back flow problem! Yay!!!  Below are all the details.  I will be sharing this solution with NuCamp in hopes that they will adopt the change.

Nautilus Check Valve Installation at Point F

Fix Steps:

1. Remove the swivel valve at point F.  The Pex pipe connected to this leads directly to the hot water heater.
2. Remove the union at point F being careful to not loosen any other components of the harness / valve body.  Crescent wrench or 22 mm box open wrench required
3. Install the check valve with the arrow pointing in the direction of the flow - up in the case of the P3. Use a 20 mm box open wrench 
4. Replace swivel valve back on point F. Take note that the check valve is between 1/4 and 3/8 of an inch longer than the Union so the blue Pex to F may be a little less than square
5. Pressure test for leaks

Process for pressure testing:

1. Test for leaks with city water by running cold water through hot and cold lines without turning on hot water heater.
2. Partially fill fresh water tank
3. Switch to Dry Camping and test for leaks using just cold water and pump.  Test hot and cold lines without turning on the water heater.
4. Turn on hot water and continue to test for leaks in Dry Camping mode
5. Test for hot water backflow in Dry Camping mode by continuously running cold water until fresh water tank is empty.  Upon empty, verify that hot water does not flow back out of the hot water tank to point F

***just a side note***  I am currently experiencing a small leak at the first Pex elbow away from the Nautilus on line F after performing this fix.  I ran out of daylight and need to borrow some Pex crimp tools.  I’m pretty sure it is a result of the Pex sitting up 1/4” from its original position and possibly some torque on the joints that needs easing from repositioning.