2021 Tab 320S Alde hot water tank will not drain

Muffinman

When winterizing I have trouble getting the water to drain from the Alde unit. Hot water taps are open and yellow flapper valve is up, but very little water comes out (maybe 2 oz). In 2021, I removed the clear hose going to the automatic check valve and tapped/jiggled that area. I then heard air being sucked into the tank through the valve to relieve the vacuum lock and the tank drained completely. ( I collect and measure the water that drains) In 2023 the same thing happened but I couldn't relieve the air lock. I ended up using a 6 inch zip tie and pushed one end into the check valve area. Each time I did this, I heard air being sucked into the tank. After about the third time the valve stayed open, air went in and the tank drained completely. Am I doing something wrong that causes this problem? What is the fix? Any suggestions are appreciated.

pthomas745

The Alde hot water tank is drained in two ways: from the Yellow Valve, and also from the cold water low point drain.  You may have drained quite a lot of the tank from the cold water low point drain.

The clear tube coming from the Alde attaches to that "red" valve connector on the Alde, and it is the vent that helps drain the tank.  That red valve needs to be configured properly to make sure it actually works as a vent.  Find the comment by "Paul1959" in this thread with an owner with the same type of concerns you are raising.

And, welcome to the Forums!

https://tab-rv.vanillacommunity.com/discussion/14516/alde-boiler-drain

mgreen2

On a 2021 320 you have a hot and cold water low point drain under the Nautilus panel. If you open both of them you will get a lot of water to drain. After this if you open the yellow flapper there will only be a small amount left, like you describe. Just whatever is left in the hose. If you are winterizing, after draining you close the hot water bypass valve. The fresh water tank drain is on the passenger side, behind the wheel. Raising the front of the camper helps drain everything from this tank. 

Muffinman

Thank you for the suggestions/ideas. When draining the waterlines and Alde tank for winter, I open hot and cold water taps as well as the low point drains and the Alde drain. I collect water from the low point drains under the Nautilus in one dish and the Alde drain water in another. There is very little coming from the Alde until I can get air to enter via the automatic check valve.  
Reading the Paul 1959 thread, as suggested by mgreen 2, it seems likely that the ball valve is stuck. Perhaps it is orientated wrong. The clear plastic hose is attached to a horizontal outlet on the check valve. 
The trailer is remote from me in winter storage so once I get it back in the spring I will check out the improper orientation hypothesis. 
Thanks again for you help...much appreciated.