T@B 400 Tank Heaters

Awca12a

Working off of a post from user @skwhee I followed their lead and after opening everything up, I was hoping for some forum input on what I'm seeing.  The design called for two ThermaHeat RV Valve Pipe & Elbow Pads which are 13" x 3" on each of the 29-gal fresh tank and the 17-gal grey tanks.  Looking at the tanks with the coroplast belly pan down, the fresh tank is 52" L x 24" W x 5.5" deep while the Ameri-Kart grey tank is 54" L x 14" w x 6-1/2" deep.   That made me think the grey tank needed all 4 of the pads given it's length and the inability to install insulation below as it rests on the belly pan.

Each pad gives out 7.5watts so 30-watts total isn't a bad trade-off for each tank to be kept above freezing.  Problem is that these elbow pad units don't have thermo-regulators like the larger pads designed as tank heaters.  Those pads put out 60-watts over an 18 x 12" surface.  So the question I'm hoping some users here can chime-in on is what would be the result if the 4 non-thermoregulated pads were left on, perhaps even by accident during warmer months, or otherwise turned on during colder months and left un-monitored.    Is it worth it to put on the larger pads with the thermoregulation or are the smaller ones putting out too little heat, even if left on indefinitely, to be a concern.

My thinking is that the grey could be a problem if the material inside was heated above 67 and created gasses that had to go somewhere.
Similarly, how hot could fresh water get before it became a bacteria issue?

I'm using SJOOW 14-4 so there will be a switch for the valves, grey and fresh to operate independently of each other.   Easy enough to wire this way plus it gives another switched leg down below should some other mod ever come-up.

For the engineers out there of whom I am not.
Would you just use the non-thermoregulated pads to get 30-watt draw or change the design now that I've installed it and accept the 60-watt draw but gain thermoregulation?

Thank You in advance.

[Deleted User]

Hi there, sorry I don't have any help for you, but I plan to follow your thread to monitor your progress.  I don't have a 400, but thinking about a future purchase and would definitely like to be able to camp into late fall.

Michigan_Mike

We don't drink the water from the freshwater tank and have always just used the water for showers, hand washing, toilet flushing, etc. 

 I had considered the tank heating pads for our 400 but decided against it as we've camped in the mountains without any issues and in below freezing temperatures.  I have had the hose freeze up and learned a few years back that you are better off filling the water tank up when temperatures are below freezing as water does hold heat for an extended period of time.  If temperatures don't plummet dramatically for let's say an extended period of time 8-10 hours and things get above freezing the following day you should be fine.  

But I find the pads interesting and they should be beneficial nonetheless.  Maybe you might consider a toggle style switch with a light built in to remind you that the pads are energized.  And unless you had a minimal amount of water in the tanks it would seem a stretch that there would be a heating or gas buildup issue.  That would be a good question for the manufacturer of the heat pad.  

Good stuff, thanks for sharing your project!

[Deleted User]

Good to hear.  I was just hoping to get through those few hours it dips just below freezing in late fall.  Sounds like it would be ok for just a few hours.  

WilliamA

Interesting...
A couple of things.  
I wouldnt think that even 60 watts spread over such a large area of 216 square inches would create any problems.  The black water tanks vent to the wnvironment so that's not an issue.  More potential for problems would be heating/cooling the plastic causing it to get britte over time. I Doubt that could be an issue if there is any liquid in the tanks at all.
For warm weather shutoff, a simple 110V line voltage thermostat could be wired to the units.  That would turn them off at a preset temp.  The thermostats are not voltage sensitive and would work fine at 12 or 110V.  They simply switch a circuit off based upon mechanical temperature settings.  Not hard to do.  You could surface mount one anywhere, even in a cupboard or cubby.  Just set it to the lowest setting (around 50 degrees) and if the temp drops below that it would close the switch.

WilliamA 

gregp

I am a skier and wanted to use my TAB for winter use both with power and boondocking.  So I considered heating pads but ultimately went a different direction.  I ended up insulating the entire bottom of the trailer and extended the Alde system using a "mini" convector to heat the space.  This is more work for sure but I have been very happy with the results.  Have been in 24 degree weather with some wind and no problems.  Contact me if you want more info on how I did mine.  Good luck!

[Deleted User]

I would definitely like to hear the details.  Did you just keep the existing plastic corrugated belly pan?  

BigGrover

You guys remind me of an old friend of mine who is a mechanical and electrical engineer.  There's nothing he buys that he doesn't immediately tear into and starts working on to make it better.  While I am afraid of messing up everything his philosophy is "I can always make it better"

[Deleted User]

I wouldnt normally be in favor of this approach but it greatly impacts my ability to enjoy camping without freeze protection.  I very nearly bought an Airstream Bambi since it has a "heated underbelly" but I just dont like the look of Airstreams so much. 

Hvtymwiltravel

I just saw this thread.  I have one of the first 3 400's built so we are getting close to it's two year anniversary.  Prior to last winter I addressed this problem.  I had a good test this week on our return trip to OH from FL.  This is what I did.
I closed off the inspection holes in the frame.
I installed an auxiliary fresh water tank in the closet, using the tank used in some of the T@G campers. (drain the main and use the auxiliary during freezing weather)
I installed an Ultraheat pad on the grey tank and two elbow heaters outside near the gate valves.  Unfortunately the style gate valves used on my 400 will not accept a gate valve heater so I compromised and mounted a gate valve heater on a strip of aluminum under the valves.  The strip on aluminum does not do much good.
I wrapped  the outside elbows and gate valves with the reflectix bubble wrap.
 I installed a short 110 volt heat strip on the drain line for the fresh tank to be use when overnights gets below freezing and daytimes above freezing so I will be able to drain the tank if weather changes. (when I am still using the main tank)
I tried to add bubble wrap insulation around the underbelly but it was too bulky so I have not insulated underneath.
I added the ultra heat switch/control set in the port side compartment

On Monday we were in Northern AL and drove the 520 miles home on that day.  On Sunday night, I turned on the gray tank heater but forgot to turn on the elbow heaters before I went to bed.   Temperature at bedtime was 28 and calm  I wanted to empty the tanks the next morning but the gate valves were stuck.  The temperature was 23 at that time.  Water at the campsite was also frozen so we headed North with gray heat and elbow heaters on   I was worried about the TV electrical load but it turned out not to be a problem.  The temperature was 10 at 5pm when we got home.  Gate valves were still frozen so I waited it out until today with the temperatures in the 40's and was able to empty both tanks with no damage.
The interesting thing for me is the heat generated from the gray pad.  Not moving the underbelly temperature is 7-9 degrees warmer than the outside temperature and moving 3-4 degrees warmer. (also installed a remote thermometer in the underbelly)

The question for me is, would the elbow heaters have kept the gate valves operational if I had them on all night while we were in AL?  
Wayne

Awca12a

The elbow heaters only give off 7-watts and the plastic is pretty thick while the dump handle provides a heat sink right into the heart of the gate valve so, I'm not sure heat along without insulation will be enough.  My plan is to box-in the dump & gate valve areas so they can be insulated using riveted angle-aluminum for simplicity.  Right now I'm waiting on the specification sheet from nuCAMP for the W-1507 and H-1140 Fresh/Grey holding tanks before going any further as Ameri-Kart won't talk to an end user.  While I know the tanks are Polyethylene, I need to confirm some heat index information to make sure the heaters won't create a brittle/cracking condition a few years down the road.   If that works out, I'll drop the belly by 1" using angle aluminum, add 1" of insulation below reflective bubble insulation, thermally insulate from the side-rails and call it a day.

Wiring will be a 4-switch connector purchased from Amazon allowing dump switches to be active independently of Grey and Fresh.

@Hvtymwiltravel, what did you use for remote temperature reporting?  Nothing I've found so far seems simple and reliable enough to get buttoned-up and forgotten in the belly.

Hvtymwiltravel

Awca12a,   Sounds like you have a good plan.  Best of luck with it.                         For a temperature sensor, I used a cheap indoor/outdoor battery powered unit which I mounted in the closet. 

BigGrover

Just wondering here, but what would the practicality be of just adding more tubing and glycol to the Alde and running the Alde tubing under the tanks to heat them?

Awca12a

It’s been done and there is a good post on these threads.  For my purposes, I didn’t want to have to rely on Alde and needed a solution for when I was driving but couldn’t dump.  Electric heaters will keep the tanks and/or the valves working while towing as wind factor is an issue.  Ideal solution would be both.  

That said, just found I can use 1” ISO inside a 1” aluminum C channeling and get an R6.5 before the Cloroplast and reflective bubble insulation is factored in.  

BigGrover

Ok, Awca, I gotta ask, are you an engineer?

Awca12a

Sadly NO.  It would have made my hobbies and interests easier.  I've had to learn all the stuff I wanted to do and find out about either by disastrous experimentation or later by taking classes.  Welding class was fun, though.  I now I have a tremendous appreciation for people who can weld aluminum neatly.  Seriously, how do they do that when it doesn't even show a visual change while heated.   But I digress.

BigGrover

You amaze me, and your technical writing is top notch and greatly appreciated!

xheavy

Gregp I would like to like more about your modifications. 

atlasb

Not to hijack this thread but I remember some time in the past some one installed a computer fan in the floor of the Alde compartment to duct excess heat to the Tank area below.  I know that in our 400 the Alde compartment generates a lot of heat and will heat the top panel below the upper section of the bed and keep it toasty.  Just a thought and may a simple option for additional heat in the tank area.

Sharon_is_SAM

@Dalehelman, did an experiment on his TaB out in his garage using a fan and the Alde heat.  

Awca12a

Finished the wiring and starting on the actual heat use testing under variable temperatures to determine the 24-hr AMP HOURS used.  Should be interesting.   My working theory is that it won't be on full time and will draw a fraction of those amp hours rated over an evening.  By breaking it up into 3 circuits, can manage the worst temps with just dump & grey leaving fresh for while we are hooked-up to shore power.   Attached is the wiring and equipment details used in this particular build.    The 1st photo shows a dragline was included for future wiring if needed because getting up that particular chase was difficult.  The solution was to use a plastic fish with the curved part facing the outside and positioned in the innermost corner closest to the rear and drivers sides.  That position lets the fish wire get down fairly easily.

Minor mods and reposted below

PamandJohnUpNorth2

 Wow, that is some awesome documentation, @Awca12a ! Thanks for sharing with the community.

Awca12a

Minor detail updates to show materials needed @ lengths.