Portable Water Heater for a Hot Tub or Pool

I recently purchased a portable hot tub - Intex PureSpa 6-Person Portable Inflatable Bubble Jet Ho t Tub. While looking at the specs and reviews I was concerned about the heating capacity of the unit. The 1,300 Watt heating unit only heats the water 1-2 degrees Fahrenheit an hour. Customer reviews also indicated they had a significant increase in their electrical bill. This information lead me to come up with a portable water heater solution. I am not a handyman by any means so suggestions and optimization ideas are very welcome. Please let me know what you think for my first Instructable.

Step 1: Pieces and Parts

Here are the basic pieces that I used to make the portable hot water heater.

Camplux 5L 1.32 GPM Outdoor Portable Propane Tankless Water Heater

Flojet 03526-144A Triplex Diaphragm Automatic W ater System Pump, 2.9 GPM 50 PSI, 12 volt DC

4 - 1/2 to 1 1/4 " stainless steel hose clamps

2 - 1/2" galvanized coupling

2 - 1/2" Male NPT X 1/2" Hose Barb

2 - 10' braided vinyl tubing 1/2" inner diameter

Kastar AC Adapter, Power Supply 12V 6A 72W

Teflon Tape

Wrench and Screw Driver

Step 2: Making the Water Connections

Apply Teflon tape to the threading and hand tighten the 1/2" coupling and 1/2" to hose barb to the water inlet and outlet on the water heater unit. Affix the hose to both of the hose barbs and tighten with the hose clamps.

Step 3: Connect Hosing to the Pump

Using the hose barb connections supplied with the pump attach the hoses and tighten with hose clamps. Ensure you follow the directional arrow that indicates the flow of water through the pump so it draws water from the water source and into the water heater.

Step 4: Connect the Propane and Check for Leaks

Connect the supplied propane supply line to a 20 lb propane tank and check for leaks by using soapy water on connection points. If you see bubbles turn off the propane and tighten that connection point, do not overtighten. Once no leaks are detected mount it in a safe location. It must be mounted outside where adequate ventilation is provided. I had plenty of space under my deck where the heat could dissipate and not overheat the wood.

Step 5: Attach the Power Supply to the Pump

Attach the power supply to the water pump. The outside of the barrel is negative (-) and the inside is positive (+). Do not plug the pump in until all water connections are attached and the suction end is submerged in the water.

Step 6: Check All Connections and Turn It On!

Check all connection points to ensure they are adequately tight and not leaking. Ensure propane is turned on. If not already installed place the 2 D cell batteries in the water heater. Ensure both ends of the hose are underwater. The suction hose must remain submerged at all times.

When you are ready to connect the pump power supply and water will begin to flow. Once water flow is detected in the water heater it will auto start the flame. You can view this in the flame window on the front of the water heater unit.

Relax in whatever you are heating and watch the temperature rise. Be careful, if you have the water flow turned low and the gas high it is capable of producing hot enough water to scold and burn. This should be supervised at all times by a qualified adult.

Enjoy! :-)

Step 7: Follow Up / Updates

Thank you to everyone who built or provided suggestions for this project.

Something that appears to be a reoccurring problem is the pump overheats. Quite a few commenters suggested using a hot water based pump. I am curious to replace that original pump with one designed for hot water. I am not sure if it will have the same water pressure as the original pump above. I am suggesting this pump as a replacement 3 GPM hot water pump