Hot Water But No Heat - 2020 T@b 400

Pekoe1111

Just bought a 2020 T@b 400 and the hot water works fine but the heat does not. The white Alde bathroom heater is cold to the touch. My Room Sensor indicator is gray, not blue. Could that be the problem?  All other settings appear to be correct (not on Delay, propane lights green). Some of the red plastic water lines near the Alde unit feel cold. Could there be a valve closed somewhere?  Thanks!

Pekoe1111

Glycol and water temps are 176 deg. 

AnOldUR

Glycol level?

MuttonChops

Pekoe1111 said:
. . . Room Sensor indicator is gray, not blue.

I don't understand 'Room Sensor'.  Please provide clarification; pictures and/or user manual references.

Pekoe1111 said:
. . . hot water works fine but the heat does not. The white Alde bathroom heater is cold to the touch.

Alde System uses City Water Pressure (or the Water Pump) to move hot water from the Alde tank to the sink/shower.  For Cabin heat the Alde has a stand-alone Circulation Pump to move the hot glycol.

1]  Confirm the Glycol Expansion Tank is at the correct level.
2]  Can you hear the Circulation Pump running (or feel it vibrating)
3]  Consider resetting the Alde System to factory default conditions.
      Control Panel Service Page,  RESET button,
        Now confirm Cabin Heat is set to a temperature above actual cabin temperature,
        Check the Setting - Circulation Pump Screen; confirm it is set to Therm
          Therm: The pump is controlled by the room sensor.
          This is the normal mode for heat and hot water.

Reference:

Pekoe1111

Thanks for your help. I reset the system and settings are set where you indicate they should be. Glycol tank in dinette window is half full. Tomorrow I’ll feel if the circulation pump is working. This is the screen that the manual says you can choose between dinette or bedroom sensors for thermostat. I may have to postpone dealing with this until Spring because I have interior it and get it into my friend’s barn for the winter. 

MuttonChops

@Pekoe1111 ;
To the best of my knowledge nüCamp does not install extra cabin temperature sensors.
The only sensor is in the Control Panel.

So make sure your "Setting a room sensor" is not active or set to Auto.
It being grayed out suggests that feature is not available/active.

Let us know when you have had a chance to experiment with the Alde System again.

Pekoe1111

Does the circulation pump have a fuse or breaker?

pthomas745

The circulation pump is 12V and is wired directly to the Alde motherboard with a connector.  On the Alde 3010, the connector for the pump on the board is in the upper right corner.  The Alde 3010 manual has a picture of a wiring schematic for the board, but the 3020 manual does not.  If you take the "service hatch" (the plastic cover on top of the Alde) off, there should be a schematic glued to the back side of the cover that will show where the connector for the pump is.

Slackers

I had this problem after a glycol exchange and merely had to turn up the pump speed (at the Alde unit under the bench).

RPMustang

Same here on turning up the circulation pump speed after a glycol exchange.

Disenchanted

Hopefully some are still monitoring this thread... 2020 T@b 400 - was in 25-40 degree temps.  Heat worked great for three days (kept me toasty at 60 degress plus).  I vented the rear heat exchanger (it had a bit of air that came out of the vent tube at the rear of the bed, and got hot glycol out once the air vented off.  The next day the heat stopped working.  I had plenty of hot water, glycol/water temps of 176 degrees, expansion tank half full. 

I tried the tilt down, tilt up exercise two times, ran the alde circ pump all the way up high. 

I have a flow unit and the rubber tube that comes out of the flow unit to the flo pump and also on to the heat loop, was HOT to the touch and very hard.  The rubber hose that goes to the suction of the alde pump was cold to the touch, and squishy... i could pinch it closed and let it spring back open.  I vented the kitched heat exchanger (under the sink) and the bathroom heat exchanger (glycol right away, no air).

It seems like there is a blockage in the heat exchanger loop.  Has anyone experience a failed check valve (that is the only component downstream of the Alde/Flow unit before the under bed heat exchanger).  

Any ideas??

Disenchanted

UPDATE - My Alde Heat has not worked since March of this year, when it suddenly stopped working.  I have taken enough of the trailer apart to get to all of the radiators and done some more troubleshooting, but have still not found the problem.  Good news is that there is some (probably limited) flow to the first (rear) and second (under kitchen) radiators in the heater loop.  but i believe there is either blockage in the system, or a pump is not working correctly.  Here are my current observations:
1. I have a 2020 NuCamp Tab 400, with the Alde Flow installed. 
2. I operate the Alde with the hot water boost OFF, and the glycol heats up to 172 degrees F, and i do have hotwater.  Both glycol rubber hoses from the Alde Unit to the Flow, and the recirc back from the Flow to the Alde Unit are hot - 140 F.  The recirc pump from the Flow unit is OFF (wires disconnected), yet there is significant flow back to the Alde unit bypassing the pump, indicating that the "return to Alde" flow resistance is less than the heater loop flow resistance.  
3. the Hose from the Flow unit that goes to the heater loop heats up to 90 F, but no higher (suggests to me there is flow blockage in the heater loop).  I am pretty sure there is no air in the system.  I have done so many tilt up/tilt down cycles and so much venting of heaters that any air has been vented.
4.  The Alde recirc pump does appear to run.  If i raise the setting to 5 on the pump i can hear it "whirring" and when i turn power to the unit off, the whirring noise stops. 
5.  From the thread on "Changing out Alde fluid" @BrianZ and @Denny16, there should be a "non-return valve" on the "suction side" of the Flow Circulation pump, but there is not one installed on my system.  
6. When i insert the special tool (bent pipe with stopper) into the Vent tank outlet, and Pump glycol into the system, i get a significant pressure buildup in the pump discharge, indicating there is some blockage in the heater loop somewhere.  

My planned Next steps:
a. drain glycol from the drain fitting under the trailer.
b. disconnect the hose from the outlet of the flow unit (that also goes to the suction side of the flow circ pump), and visually inspect the hoses to the inlet of the rear heater for crud/foreign material/blockage.
c. if no blockage is noted, then try to pump glycol thru the heater loop from this location (pumping into the rubber hose connected to the inlet side of the rear heater.
d. swap out the Flow Circ pump for the Circ pump for the central heating system that feeds glycol from the heat loop (suction side) into the Alde 3020 unit.  (rationale - IF there is a problem with the 3020 unit pump (because it has the most run time), the Flow unit circ pump should fix the issue and i'll know whether i have a bad pump.  

@ScottG , @Denny16 and any others... any additional insights or suggestions?

MuttonChops

@Disenchanted;  Are you sure there is not a 'non-return valve' on the Flow Pump line.
The Alde literature indicates that a valve is on the discharge side of the pump, not the suction side as you noted.

Consider plugging/blocking the Flow Pump to Boiler Line for troubleshooting; force glycol to flow into heater loop to see if problem is the Flow Pump or non-return valve.

Disenchanted

You are correct @MuttonChops, I found the check valve on the Flow pump discharge, that circulates back to the Alde unit.  It prevents recirculating of glycol from the flow to the Alde unit unless the flow unit is running.  The diagrams are a little misleading since they show the outlet of the non return valve going to the heat loop (which it does not).

Disenchanted

Great news, I found and fixed my heat loop problem and even know the root cause.  It took me 18 hours basically disassembling the entire heat loop joint by joint with lots if interior cabinet disassembly required ( shout out to @bergger who’s article “T@b 400 Convector Locations” was a huge help).  I’ll give a short summary and then detailed explanation of the chronology that led to the issue, and the steps I took to correct it.

SUMMARY:  the entire heat loop was clogged with crystallized glycol chunks. 

The top photo is looking into the end of one of the aluminum pipes, the middle picture looking into one of the rubber connectors and the bottom photo is collection of some of the crystals removed from the loop.

the crystals were blocking the glycol flow thru the heat loop so that when I ran the Alde system it just recirced the glycol from the Alde unit to the Alde Flow unit and back, so I had plenty of hot water while freezing my butt off in Northern Idaho.

i disassembled the heat loop, joint by joint, reamed out the piping, and convectors with a flexible “spring wound” cable guide, flushed the rubber connectors in a sink with a wire brush and then dragged a wire brush thru each convector and section of piping I could not physically remove.  Pic below shows the tools I used to clear the pipes/convectors.

After reassembling the loop, I refilled the system with glycol following the steps @ScottG outlined in his article “”Changing out the Alde fluid”.  To reduce the chance of crystals forming again during winter storage, I added some concentrated glycol to the two bottles of Century Heat ready use transfer fluid, and used the super concentrated fluid in the vent tank as well.  When I tested the heat after repairs, each radiator measured at least 115 degrees F when the glycol was circulating.

special thanks to @MuttonChops @ScottG @Sharon_is_SAM and @Bergger for their help during this 10 month journey

pthomas745

What this debris would indicate is corrosion already started in your Alde loop somewhere.  That hose you are holding in your hand: did you remove that aluminum fitting in the hose and inspect it?  If that is the "

non return" valve being discussed, the corrosion could be coming from the aluminum fitting that has already deteriorated, and the "flaking" you see is the corrosion itself.  No amount of fortified glycol will fix this.

So, what did that aluminum fitting look like?

This thread is a long discussion of the corrosion issues in the Alde which might explain more.

https://tab-rv.vanillacommunity.com/discussion/13226/corrosion-of-alde-convectors/p1

Disenchanted

DETAILED EXPLANATION:

May 2024: serviced my Alde unit by flushing the glycol using the tubes, fittings and hand pump described by @ScottG.
Nov 2024: while camping in northern Idaho, the Alde heat worked for 5 days, and then stopped working, though I did have hot water.  The vent tank level indicated there was a leak, which quickly depleted the 1 pint of reserve glycol I carried.

upon return to home, I lifted the bed panels to access the Alde unit to try and find the source of the leak, hot glycol was squirting out of the rubber hose to aluminum pipe union that directs glycol from the Alde unit to the flow unit.  Upon investigation, I discovered that the aluminum pipe was split and distorted at one end, which prevented a good seal with the rubber tubing (see photos)

Since my Alde unit had never been serviced, I surmised that the defective pipe had been installed during manufacture.  I installed a PVC pipe to restore system integrity while I contacted NuCamp for a replacement aluminum tube.

CRITICAL MISTAKE: Since I would need to drain the system down to install the replacement aluminum tube, and since I would not be using the trailer or Alde unit anymore that season, I left the glycol partially drained and placed the trailer in storage.  Although winter temps did not drop below -15 degrees F referenced in the Alde manual for crystallization point of the 60/40 glycol mix, I suspect the exposure to the air-glycol interface of the partially drained glycol loop, in addition to sub freezing winter temps caused glycol crystallization to occur. 

I worked with Michael Skidmore, NuCamp customer experience manager, who was able to send me a replacement piece of aluminum piping.  THANKs Michael.

March 2025:  installed the replacement aluminum pipe and refilled the glycol side of the system. returned to northern Idaho, living in my trailer during some construction work.  The heat worked great for about 4 days, then stopped working, while the hot water continued to work.  (In hindsight, during this period, glycol crystals that had formed over the winter were circulated into and accumulated in the heat convectors and associated piping.

April-August 2025: tried various methods to restore the heat loop, tilt the trailer up, tile down vent convectors, measure convector temps while running Alde, all to no avail, but hot water was available the whole time.

finally this past week, I drained the system thru the drain plug underneath the trailer, and noticed an accumulation of crystal sludge in the funnel.  When I disconnected the rubber union that directs glycol from the flow unit to the rear connector, it was clogged with crystals.  After disassembling a couple more of the easy to reach rubber connectors, and finding clogging in each place with some pipes nearly 100% blocked, I began a complete disassembly, and clearing of crystal residue.  The hardest convector to get to was the one under/behind the front right hand bench seat.  The floor of the storage compartment was screwed form the inaccessible bottom!  When I reassembled the bench, I drilled a finger hole in the floor and did not screw it in place, in case I ever have to take it apart again!

I did learn that both the Alde circuit pump and the flow unit circuit pump are identical pumps.  Since my unit is 5 years old, I swapped them out, figuring the Alde circuit pump got much more run time than the flow unit pump ( only operates when in hot water boost mode).

Happy to say my Alde heat is working again.  The system is great…when it works, but so frustrating when it gets finicky.  Regardless, I still like my NuCamp T@b 400 trailer.

Sharon_is_SAM

Wow, you really have an intimate knowledge of your Alde system now!  Sorry you had to go through that.