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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    27 Discussions

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    gloriag22

    Question 24 days ago on Step 6

    That is exactly what I did. I sure wish it work right thou. Worked right the first time I used it. Now it runs for a few minutes, maybe, then the water coming out of heater starts to stutter. Then the flame goes out. Pump starts to pulse. I have had 4 different pumps and at least 3 different power supplies on it with the same results. I now have exactly the same parts you used. Same result. The only thing different is I am using 5/8" hose instead of 1/2". Starts stuttering then shuts off. Any help would be greatly appreciated.

    4 answers
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    Jimbo95220gloriag22

    Answer 23 days ago

    12 volt rv water pumps a not generaly used on hot water, that could cause the problem. There is hot water circulation pumps for hot water heaters for homesto circulate hot water to distant bathrooms. $70 range might help

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    gloriag22Jimbo95220

    Reply 23 days ago

    Well I had one of those hot water pumps and it did the same thing. I got the exact same pieces this guy that did the instructable has. With one exception and I think that is causing the problem. I used garden hose and he used reinforced vinyl tubing. I think now the problem it that the hot water is collapsing the hose and the water can't get through. Thanks for the answer tho

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    Jimbo95220gloriag22

    Reply 23 days ago

    The 12volt pump shut off on pressure. If the intake is collapsing i think the pump wouldn't shutoff. They will shut off if they overheat and come back on after it cools. That info is from shurflow site

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    jimrock66Jimbo95220

    Reply 22 days ago

    Mine is over heating and comes back as it cools. I am using the reinforced vinyl tubing.

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    jimrock66

    22 days ago

    Everything seemed to work well then the Flojet motor kept overheating every 15 minutes and stopping for about 15 minutes. Going to try the Camplux motor next. This whole project is a great idea if I can get it to work right. Any other suggestions.

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    jimrock66

    25 days ago

    Built one just like you did, but I put mine on a hand truck. Thanks for the idea. I tested it on a tub of water, and within minutes the water was steaming. Going to use this on an Intex six person bubble tub. I love the hand truck setup.

    20190223_141252.jpg20190223_141257.jpg
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    gloriag22

    Question 5 weeks ago on Step 6

    I did your set up and all worked great until the pump stopped. I used a pump from an RV I had. Doesn't seem like the heater is letting the water go through. Plenty of pressure in the inlet hose and the hose from the pump to the heater. The heater will kick on and run for a while and shut off. Water is just a trickle coming from the heater. Any ideas. I was wondering if you could use a pump designed for actually moving water from one place to another. I saw a 110v pump on
    Amazon that seems like it would fit the bill.
    https://www.amazon.com/dp/B0747P8C65?psc=1&pf_rd_p=7ebdab82-de3b-42f2-8032-aa63ae38b0fa&pf_rd_r=C22929MTCP8358FXWTH6&pd_rd_wg=LyM3q&pd_rd_i=B0747P8C65&pd_rd_w=AXJIf&pd_rd_r=b74266fb-9ef5-4fc4-968d-1a053fc16ab2&ref_=pd_luc_rh_crh_rh_sbs_02_03_t_img_lh

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    Bklanker

    7 weeks ago

    Would it be possible to use this set up for a small above ground pool? Could the pool pump be used in place of the Flojet pump?

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    weber713Bklanker

    Reply 6 weeks ago

    Conceptually yes I do think it should work. I was looking to do the same with my pool. I have not yet tried it but had a few thoughts; I was planning on adding a three-way valve ( https://amzn.to/2MJg8ns ) to divert water to the heater and have an inline hook up. I was thinking about placing it after the filter (to protect the heater from impurities in the water) and before the chlorinator ( to reduce build up of calcium in the heater). I may tackle this in an instructable in the spring. If you do end up doing it let me know how it works :-)

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    bsawhill

    Tip 2 months ago on Step 3

    There are actually THREE sections of hose, not two: one from the heater to the pump, one from the heater to the tub and one from the tub to the pump. Or am I seeing things?

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    weber713bsawhill

    Reply 8 weeks ago

    You are not seeing things you are 100% correct. Thanks for noticing that :-)

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    AlexN200

    Question 3 months 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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    weber713AlexN200

    Answer 8 weeks ago

    Great question, it's rather hard to answer. I was using a standard 20 lb propane tank like you see on your grill. The system heated water that was between 70 and 80 degrees about 1 degree every 2-4 minutes. The 20 lb tank supported the system for over 30 uses and we started with it at half full.

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    EileenD24

    Question 2 months ago on Step 5

    Thank you for your post. Very kind of you. We just got the same INTEX spa tub (6-person). It took four days to get to 104 degrees. As soon as we took the top off, it dropped to 102. Turned on the bubbles and we were down to 98 degrees in no time. We like our hot tubs HOT HOT HOT so these water temps made it feel like a warm bath and not worth the investment/was disappointing. So, I'm not as concerned (although it's very costly and we are impatient) with the time to heat; I'm most interested in getting the water to at least 108 degrees and to be able to sustain this temp even if we put the bubbler on. Would you say your solution would achieve this? Any additional recommendations/suggestions. THANK YOU VERY MUCH FOR YOUR FEEDBACK!

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    Oranges Rhymed

    6 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 5 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 6 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 5 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

    6 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!