Installing a 25G water tank.
I have a 25G water tank installed under my 2017, 148 medium body tall roof Transit.
As it turns out, there was a shipping mistake and I ended up with two tanks so one is for sale at $100. (R-RVB546, 62x14x7.5)
Here are the details.
It is on the driver side, under the floor, between the gas filler and the rear suspension mount.
Insulation is not required but I did insulate mine with 1/2 inch R-max on all sides except the top. The top has 2" R-max, except where the floor beams are located, where there is no insulation.
The bottom also has a layer of fiberglass sheet to protect the insulation and tank from road junk.
A series of 4 long (about 2.5') hose clamps are used to hold the tank. The clamps are cut such that the clamp screw is near the gas tank with the clamp running under the tank. Each strap has 2 steel pop rivets into the sheet metal on the outer wall. Next to the gas tank I used riv-nuts (using exiting holes) to bolt aluminum angles (2x2x.125) to the frame. The other screw end of the hose clamp is pop riveted to the aluminum angle. Cut / arrange the strap such that the screw mechanism is near the gas tank along the vertical side of the water tank. Pre-bend the straps to match the final tank location. Push tank into place and tighten the straps. I also placed a 1.5 x .5 inch aluminum U channel under each strap to spread the load. The full tank weights about 120 pounds or 30lbs per strap.
When test fitting you will need to remove some of the insulation in various places that include the rear, outside rear and inside front to provide clearance to various body parts and the gas fill hose. The gas fill hose mounting bolt needs to be loosened and the hose shifted forward. The gas tank straps (roughly .125 steel) have an unnecessary flange. I removed roughly ¼” of excess metal to avoid removing more insulation. You can skip this step if you remove the insulation in those areas.
There is a ½ vent line that goes up into the body cavity next to the gas line. It has a screen over the end to control potential bugs. The tank is full when you see water running out near the front of the tank.
I fill and drain using two hose fittings (garden shop quick connects) attached to the body sheet metal at the front of the tank. I use a household water filter located inside the van above the tank. The water lines run through an existing hole in the body sheet metal (it normally has a plastic cover) that is near the front of the water tank. Either there is an existing hole or I cut a hole in the wall cavity floor to allow the hoses to go into the wall cavity behind the drive side pillar.
The water goes into the quick connect, up through the wall and floor to the water filter, then back through the floor and wall to the ½” tank fill. The other ½” fitting has a T. One side is the drain, the other goes up through the wall and floor to the water pump.
All pipe and hose is plastic. I also added a heating pad (under the insulation near the bottom front of the tank), 12V heating wire (around the water pipe/hose and valve) and a temperature sensor. The pipe and valve have several layers of the 1/8” stick-on foam pipe insulation (home depot). A $5 controller is used to turn on the heat if it gets near freezing.
When completed I bent a sheet of ¼” ABS plastic to protect the front of the tank from road junk and increase the insulation.
The lowest part of the install is about 1.5” below the outside sheet metal. It could be 0”, with no insulation. In several trips with 45 degree days and 20 degree nights the temperature at the insulated pipes never got below 36 degrees. I’m sure it would get to freezing on a colder day but the insulation does a great job of holding in the heat.
Pictures are attached but I don’t have a lift so they are pretty poor.
It does take time to do this install but it saves a lot of interior space and (for us) provides plenty of water for 5 days of camping.