update on Tab 400 tank heater mod.

Tundra57

Last year I fitted a radiator in the covered area under the tab to heat the tanks in winter. I used two bypass valves to route part of the Alde flow down to keep the tanks just off freezing.

Currently, the Tab is parked by my house. Plugged into electric with 1 kw selected and gas on Alde. All water drained. Hot water off.

Tab heating set to 65.

Temperature outside has dropped to 25 F degrees, but my probe is recording 43.7 degrees in the insulated tank area and 65 in the Tab. So the mod seems to work.

I'm running the system for a week or so before running antifreeze thro to winterize just to see if this effect is maintained.

Sharon_is_SAM

Great!  Would you use this under tow or just while stationary?

@Dalehelman did something with a lamp and fan as I recall.  Dale - what did you do again to keep the TaB underside warm?

TNOutback

Hey @Tundra57, did you insulate the inside of the bottom cover any?  I can’t recall from your earlier posts.

I am probably going to drop the bottom and put on heat tape on the water drain/pickup lines coming from the fresh water tank, leaving the plug end accessible at the cut out in the frame.  At least I would have some protection when I have electric hookups and winter camping in the Tennessee state parks.

Dalehelman

Sharon_is_SAM said:

Great!  Would you use this under tow or just while stationary?

@Dalehelman did something with a lamp and fan as I recall.  Dale - what did you do again to keep the TaB underside warm?

I cut a 3” hole under the passenger side rear seat cushion. Then mounted a computer fan to force warm air into into the space below. I don’t rely on it while traveling. Because when we travel south temperatures can get to 0*F and below. At 65 mph I doubt if it would stay warm enough. 

Tundra57

I would not use while traveling as I have been advised having gas on is a bad idea. Also the bottom of the Tab would be much colder with the air rush.

I took off the bottom cover and put 1" solid insulation panels underneath. Both on the bottom and againsr the sides on the inside. Also stuck sheets of Lucite over the large holes in the frame sides.

Then put the black sheet cover back on. As this would leave the drain cock sticking down to get frozen, I fitted an electric powered normally closed valve inside the covered area and just poked a rubber drain pipe through the cover. No leaning underneath to drain it now. Just click the switch. It takes no power once it lands in the target position. I did run 12V power cables to the dump area, with a plan to add heating cables later.

But i want to box them in with a door to open.

I hit a chunk of rubber on I81 that wiped out my black water valve a few months ago so I know the area needs protection. Then i can blow hot air through from the tank area.

Job for the winter.

Still using the camper at the moment.

TNOutback

@Tundra57 what valve did you use?  I would like to find a non-powered ball valve with a long stem on it so I can put the valve inside the bottom cover with only the stem handle on the outside (and a length of rubber hose as the drain). Having trouble finding a valve like that.

Tundra57

@TNOutback I used a powered valve from amazon so i could keep the valve part in the underneath. I put in a small aux panel powered off a circuit breaker under the 3 way fridge in the tab. The valve has internal switches to indicate open or closed. Power it to open. Turn off to close.

Ill look up on my amazon account for the part number.

TNOutback

Today I dropped the bottom sheet and “permanently” attached an electric heat cable to the pickup and drain lines coming from the freshwater tank. I left the plug end with some slack just inside the frame cut out (I keep a magnetic vent cover over the opening.) The temperature sensor on the end is just outside the bottom cover where the drain valve is located.  A 3 foot cable would have been sufficient, but I had a six foot version, so the ‘extra’ cable is just filling some of the space around the water tank.  I plan to get a 3 foot one I can use on the exterior sewer valves if needed. @Tundra57’s method would be preferred, but I’m not that adventurous with a camper still under warranty!

Tundra57

It was a risk. :-).

Tundra57

In retrospect, i dont know i would go that way again. The only plus is if i am boondocking. The under tab heating is gas powered, so i dont use any electricity 12vdc or 120v ac.