Bambi holding tanks..HEATED..CONFIRMED

[dtbw]

This is really of interest to the Bambi owners as there has been discussion as to whether and how the holding tanks are heated. I have been installing a "brand new" Thetford Thermasan system in my rig (Thetford actually stopped selling them back in the 80s due to high cost low sales...I will post the installation story and some pics once I am finished). For those that don't know, the Thermasan was a patented, independently certified (National Sanitation Foundation) system that pulled filtered waste water from the holding tanks and BURNED it in the vehicle exhaust just behind the catalytic converters where the temps are 200-300 degrees above the total destruction point of viruses, bacteria and odors. These systems were installed on virtually every GMC motor home of that time and Airstream actually offered it as an option during the early 70s. The system only adds about 2 gallons an hour of water to the 25 or so gallons an hour that burning gasoline or diesel fuel produces. I found two of the units in original packaging on eBay, knew what they were, so took the gamble that I might be able to make one work (only paid $100). Anyway, I am almost finished, just have to build a circuit to replace the old mechanical speed transducer that Thetford used back then (not an issue for me as I am EE). As a side note, I have found that the pump is still made and all parts are available, so the rest is actually just tubing and stainless steel, not much that can go wrong

Anyway, back to the subject. Since the installation required me to "invade" the black water tank and install a screened extraction probe, I had to remove the lavatory front section (it comes out without removing the lavatory or top surface). This not only gave me easy access to the black water tank (man did I have to think awhile before drilling that 1 1/2" whole in the side of the tank), but it provided me with a perfect view of the heating duct to the tanks. The duct is directed thru the subfloor directly into the belly pan area just above the gray water tank. The black water tank is partially above the subfloor and partially in the belly pan, while the gray water is totally below the subfloor. The heat simply circulates around the gray water tank and then back into the trailer via the space around the black water tank where it passes thru the subfloor. This actually is a good setup as it ensures circulation around both tanks. So, while the limits of freeze protection that this provides is unknown, the two waste tanks on the Bambi are certainly heated. A side benefit of the arrangement is that the plumbing associated with the shower is also in the heated space.

[Silvertwinkie]

Hey David,

Thanks for posting your findings. I saw some ductwork coming off the side of the furnace, but was unsure it was going where I had hoped!

Eric

[WayWard Wind]

Thanks David for the confirmation. I had called A/S sometime ago regarding the heated holding tanks & was told they were heated. Never the less I removed the shelf of the sink cabinet & could see where the flexible heat duct took off of the furnace & went to the back where it disappeared, presumely to the grey water tank. As you said the black water tank sets partially above the floor & gets it's heat that way. Just as I was told by A/S. I would be interested to know just how much & how you dismantled the front of the lav, as I looked that over ( rather quickly) & really could not determine how much had to come off. I could see the black water tank just from removing the shelf. I REALLY would like to install one of those black water flushes, but to be truthful I probably would chicken out when it came to drilling that hole thru to the outside. sure would have been nice if A/S would have done it the first time. Perhaps when we go to the factory in Oct I might be able to have them install. Looking forward to those pics. Have a GREAT 4th.
Best,

[dtbw]

A.E.,
There are lots of screws. Remove the doors (the hinges are quick release...just pull gently on the small tab at the front of the hinge)The obvious ones are behind the little brown covers, the less obvious ones are the ones that tie the front to the top (get a flashlight and look, you will see them. Also, A/S originally intended the kickpanel at the bottom to be removable without pulling the whole cabinet front, but mine was such a tight fit that there was NO way it was coming out (fixed that after removing the front...ie I sanding it the edges until it slipped in/out easily). Once all the screws are removed, the cabinet front is still a tight fit, but you should be able to tell if it is friction or a missed screw that is holding it. I did notice the black tank flush inlet on the same end as I installed my Thermasan probe. The vacuum breaker for the flush was mounted high on the wall just below the lav top (ie inside the lav cabinet).