Portable Water Heater for a Hot Tub or Pool

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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! :-)

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    13 Discussions

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    AlexN200

    Question 10 days ago on Introduction

    How quickly does this heat the tub, and how long will a 5 gallon propane tank keep the tub heated, obviously given a particular air and starting water temp.

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    Oranges Rhymed

    2 months ago

    I built a similar system after seeing yours. I used a CAMPLUX ENJOY OUTDOOR LIFE Pro BD158 1.58GPM Outdoor Propane Tankless Gas Water Heater and a Harbor Freight 12 Volt DC Transfer Pump (Drummond- Item#63324) --290 GPH max. When I started, the hot tub was at 83 degrees. I had the water heater turned to maximum flow and about mid way on the temp. It put out 45-46 degree C water (about 114 degress F.) In 30 minutes, the hot tub was at 90 degrees F. I like it. :)

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    weber713Oranges Rhymed

    Reply 2 months ago

    NICE! Yeah I really like the ability to heat using propane. It is much more efficient and cost effective then the provided electrical heater. Thanks for the feedback!

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    Katiji

    Question 3 months ago on Step 5

    I'm stymied here! I have all the parts and ready to go. I cannot figure out how to connect the black and red wires from the pump to the adapter. Any help will be very appreciated!

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    weber713Katiji

    Answer 2 months ago

    Ah sorry, you are stumped I did not clearly write out that part. I have been working to update my current set up for this unit as well to keep it from being so cobbled together at the electrical connection. Previously what I did was took a ring terminal (this is the kit I have - https://amzn.to/2OkHSlT ). I took the ring that fit snuggly and bent it over and electrical taped it in place. The negative (black wire) should be the one connected to this terminal. The exterior of the barrel is the negative charge. For the positive, I placed the wire inside the barrel and insulated so it would not be exposed to the exterior of the barrel.

    However, I have been updating the process. I cut the end of the barrel off and peeled back the casing on the wire. This will leave you a red and a black wire. Strip and prep the wires. Using heat shrink - https://amzn.to/2OdugIZ insulate any exposed areas and Place an inline switch https://amzn.to/2ObBFse . This has allowed me to toggle the on and off much easier. I am working on refining pictures and updating my instructable to show it step by step. Please let me know if I can help out at all.

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    allthenamesaretaken

    3 months ago

    I am shopping for an inflatable hot tub, and this system seems great!

    My only question is, can the attached pumps on the hot tubs be properly drained/ winterized even when the pool is full of water, or the jets are being used? I am assuming the answer is yes, as you have an outdoor set up, but I was told they can't be.

    Thanks!

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    weber713allthenamesaretaken

    Reply 2 months ago

    Great question. No, I do not believe this unit is able to be winterized. I pull it inside in the winter.

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    Oranges Rhymed

    Question 4 months ago on Step 6

    Very nice. I have a similar Intex hot tub and I love it. The stock heater is puny, so I have considered doing something similar to your instructable. Tell me more about how much propane your system uses.

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    weber713Oranges Rhymed

    Answer 4 months ago

    Great question. I have not tracked the propane usage very accurately yet. I have been running the system for 2 weeks on less than a quarter of a tank. I can normally get a temperature rise of about 1 degree every 3 to 4 minutes. When I start a new tank I will assess the rate. I have been keeping the electric heater built into the hot tub around 85 so it has been very easy to raise the temperature.

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    weber713KKDUB

    Answer 4 months ago

    Not that I am aware of. I never leave the unit outside when it is not in use. I ensure it is off the ground and away from the water.

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    millingby

    4 months ago

    How did you bypass the 20 minute auto shut off feature of the water heater?

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    weber713millingby

    Reply 4 months ago

    Great question. I was originally worried about the auto shut off, however, it has not been an issue. I typically let the unit run for an hour and then allow the system to rest for a little while before restarting. I have not had an issue of it shutting off at the 20 minute mark.