Isotemp Spa 20L (5.3 gallon)


5.3 gallon marine-grade water heater.

This water heater is a fantastic way to get hot water by simply running or driving your van. It can heat the water through the van’s coolant lines or using the 750 watt (120 VAC) electric element off your inverter when you’re not driving. Check out our blog post about this water heater.

We sell the stand-alone water heater as well as the water heater with an installation kit that includes all the parts you need to connect this up to your Promaster van coolant lines along with detailed installation guide. Details on what’s included in kit below in the description.

$55 flat rate shipping to the lower 48 states.

2 in stock

Choose if you want the water heater only or with an installation kit. See description below for details on the installation kits.
  • Options Price: $0.00
  • Product Price: $520.00
  • Total: $0.00
SKU: 6P2023SPA0003 Category: Tags: , ,



  • Isotemp Spa’s exterior casing / jacket is made of high quality polypropylene
  • Inner tank made of AISI 316 stainless steel
  • All Isotemp water heaters use two thermostats: a temperature thermostat and a safety thermostat designed to trip in the event the tank is run dry
  • All Isotemp water heaters come standard with a mixing valve that regulates the temperature of the water coming out of the tank so that water heated to 160+ degrees can be thermostatically adjusted to your prefered temperature and extends the capacity of onboard hot water by using only a fraction of the water in the tank to produce the desired water temperature.
  • 750 Watt immersion heating element specially designed to heat water at bottom of tank
  • Robust design and manufactured to highest-quality marine standards for long service life
  • All Isotemp products are CE certified and manufactured in ISO certified facilities
  • All Isotemp tanks are covered by a 5-year limited warranty against leakage due to manufacturing defect or corrosion and a 2-year warranty on all other parts
  • Extra-thick insulation for low temperature loss, high performance
  • Extra-long corrugated coils for high heat exchange efficiency

Check out our blog post about this water heater here.

Dimensions (PDF)
Manual (PDF)

Vanlife Outfitters Isotemp Water Heater Installation Kit for Promaster Vans

We've taken the mystery and hassle out of installing an Isotemp water heater in your van! If you add on our optional installation kit, you'll get all the fittings, hose and hardware necessary to install the water heater in a typical installation. No need to order all these parts separately and hope that you have the right parts. The kit also comes with very detailed step-by-step guide on how to install the water heater and connect it to your van's coolant lines . The only additional thing you'll need to purchase yourself is the Mopar coolant to top up the system after you install the water heater. Note, our guide does NOT cover plumbing your water lines - only the installation of the water heater itself but we do provide some advice for hooking up your fresh/cold and hot water plumbing. We offer three versions of the kit. The "standard" kit with 50' of coolant hose will work for installations where the water heater is located on the driver side of the van. If you're locating your unit on the passenger side or high off the ground, consider getting the "long" or "extra long" versions of the kit which add some extra hose and related fittings. Full details of what is included in each version of the kit below. Standard Kit Includes:
  • 2x - brass 5/8″ barb to 1/2″ female NPT FNPT fittings
  • 2x - 1-1/4" x 3/4". PVC reducer bushings (these are used to protect the coolant hoses as they pass from below the van into the van and can accommodate flooring systems up to 1" in height)
  • 50 feet - Gates 28411 straight heater hose - 5/8"
  • 2x - brass barb reducing tees – 3/4″ x 3/4″ x 5/8″
  • 2x - brass barb 5/8" 90 degree elbows
  • 1x - brass 1/2" BSP female to 1/2" NPT male adapter fitting
  • 2x - 5/8″ brass barb ball valves
  • 16x - Gates 32925 PowerGrip heat shrink hose clamps (requires a heat gun to install)
  • 1x - Loctite 592 thread sealant (6 milliliters/.2 ounce)
  • 1x - Permatex high-temp red RTV silicone (3 ounces)
  • 20x - 7/8" stainless steel insulated hose clamps
  • 20x - 3/4" #8 stainless steel self-tapping screws with wafer heads
  • 1x - 6' length of foam pipe insulation
  • 10x - 11" stainless steel zip ties
Long Kit Adds:
  • Additional 10 feet of Gates 28411 straight heater hose – 5/8″
  • Additional 2x brass barb 5/8″ 90 degree elbows
  • Additional 2x Gates 32925 PowerGrip heat shrink hose clamps
Extra Long Kit Adds:
  • Additional 15 feet of Gates 28411 straight heater hose – 5/8″
  • Additional 2x brass barb 5/8″ 90 degree elbows
  • Additional 2x Gates 32925 PowerGrip heat shrink hose clamps

Additional information

Weight 435 oz
Dimensions 27 × 13 × 13 in

Water Heater Only, Water Heater – With Promaster Installation Kit