Isotemp Slim 15L (4 gallons) ($495)
Isotemp Water Heater Installation Kit for Promasters ($349)
Dimension (LWH): 21.25 x 11.25 x 11.7
Using a Marine Isotemp 20L Water Heater in Camper Van Conversion
The first step was to cut into the van’s heater lines near where they go into the “firewall”. If you open up the hood, you’ll see these hoses just to the left of the coolant reservoir. I’ve circled the area in in the photo below. You need to cut both of these. One hose will branch off to supply the water heater with coolant and the other will be the return line. This is a messy process so be prepared for a fair amount of coolant to come out of these hoses.
After cutting into the lines, I used the two Brass Barb Reducing Tees (3/4″ x 3/4″ x 5/8″). The two 3/4″ sides of this tee were used to repair the existing 3/4″ coolant line. Then I used a short piece of the 5/8″ heater hose to connect the 5/8″ ball valves onto the remaining 5/8″ side of this tee. These ball valves allow me to completely turn off the coolant flow to and from the water heater which effectively returns the coolant system to the standard, factory design.
Next, I ran the 5/8″ heater hose from the output of these ball valves down to the bottom of the engine compartment and all along the driver side of the van to the water heater’s location and eventually up into the van itself. The hose is clamped to the van in many places during this run so that it’s secure. Where the hoses enter the van, I drilled holes through the van floor and glued in 3/4″ PVC “union” fittings. This provides a durable and smooth surface so that the hose is not damaged. Keep in mind that these hoses get VERY hot so be sure to keep them away from anything flammable or that might be damaged by this heat when routing them from the engine compartment to the water heater location.
Once inside the van, I used the two Brass 5/8″ Barb to 1/2″ Female NPT FNPT Fittings and the 5/8″ Brass Elbow to connect the coolant lines to the inlet and outlet of the water heater and sealed the gaps with the Permatex 81160 High-Temp Red RTV Silicone. It’s recommended that you use Loctite 592, High Temperature Thread Sealant on the threaded connections.
I used the Gates PowerGrip hose clamps on all the 3/4″ and 5/8″ heater hose that connect to barb fittings.
In my van, the water heater is located behind a drawer underneath the refrigerator which is just behind the galley area and just front of the bed loft. It’s installed directly onto the subfloor and comes with brackets to mount it to the floor. I used most (about 35′ of the 50′) of heater hose.