Portable Water Heater for a Hot Tub or Pool

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Introduction: 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

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2 People Made This Project!

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53 Discussions

0
jonfen32
jonfen32

Question 26 days ago

Recently completed a setup very similar to this. It works great, until we turn on the air jets on the tub. Then the pump begins to sputter and the heater won't ignite. I then have to back flush the heater to get it working again. Maybe air gets trapped in the heater? I am stumped..

0
jimrock66
jimrock66

1 year ago

I upgraded the unit a little. I put a basked on for the propane tank. Now moving the unit is so much easier . I put a Camplux 10L on instead of the 5L . I wanted to have a digital reading and a more powerful heating system. It is 68000 BTU max Enough to heat a medium size above ground pool. I figured out that I needed screening for the pump so that foreign objects don't get caught in the pump. A timer for the 20 minute shut off. The timer is set at 19 min on and 1 min off in a loop. the heater continues working without resetting. I also put a garden hose bypass on the unit so you can either use a hose or the pump.


It took a while the pumps were the worst part. But I think this unit is a performer.

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0
tvengineer
tvengineer

Reply 3 months ago

I did it ! With the 10L heater and the same pump.. works great! I have run mine for well over 20 minutes without it shutting down though... maybe mine is defective or does not have the 20 minute time out, I don't know. Also, on mine, the temp display is intermittent... sometimes it works, but mostly it shows wildy wrong temperatures.. I just set it to the max heat setting and let it run until the tub is up to the temperature I want... in the future, I want to build a controller for it so I can have it maintain the tub temperature and maybe even make it remote controllable over the internet.

0
tvengineer
tvengineer

Reply 4 months ago

I want to try this exact setup on the same tub... If you don't mind.. how well does it work.. and how do you use it? Can you keep the tub heater turned off, let the water cool all the way down and use the propane heater to get it hot quickly? Or do you just keep the tub heater on and use this to supplement the heat? I also love the idea of plumbing up both the return from the tub and a fresh water supply. That way you can switch over to fresh water to rinse off after getting out of the tub. Great idea.

0
weber713
weber713

Reply 1 year ago

Wow that looks amazing. I like how portable you made the unit. The strainer and timer are both great ideas. This looks awesome! Thanks for sharing the modifications you made!

0
millingby
millingby

2 years ago

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

0
nosaints09.ns
nosaints09.ns

Reply 3 months ago

120ac to 12dc timer

0
jimrock66
jimrock66

Reply 1 year ago

I used a timer 19 min on 1 min off then back on

0
weber713
weber713

Reply 2 years 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.

0
jimrock66
jimrock66

1 year 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.

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0
tvengineer
tvengineer

Reply 4 months ago

I want to try this exact setup on the same bubble tub... If you don't mind.. how well does it work.. and how do you use it? Can you keep the tub heater turned off, let the water cool all the way down and use the propane heater to get it hot quickly? Or do you just keep the tub heater on and use this to supplement the heat?

0
jimrock66
jimrock66

Reply 4 months ago

Careful of the prices on the intex tub prices right now. There is a slowdown of production of them in China so the price has about tripled. VmInnovation and companies like them took over the market and are marking it as a supply and demand. Basicly legal gouging.

0
tvengineer
tvengineer

Reply 4 months ago

Yea... I got taken.. Wife has been wanting one for a couple of years now and we have been putting it off.. I remember the prices a year ago were around $500.. this year our normal beach trip (to a condo with a hot tub) was cut out because of the pandemic and she really wanted to get in a hot tub. I managed to find an Intex tub on Amazon and I paid right about $800 for it (OUCH).. but it is what she wanted and it was about 1/2 of what the beach condo would have cost anyway.

0
jimrock66
jimrock66

Reply 4 months ago

Yes it works well, but I have upgraded the heater to an 18L The units are much cheaper than the Campulx and can heat an 18 round pool a few degrees an hour. With the pool you will use a full tank of a 20 pound tank, but if you want to extend your season or a party and just a few degrees, this is perfect for that. If you have piped gas to your house this is a very reasonable alternative to a pool heater. Faster cheaper and new heater is stainless steel and can be bought on ebay for one hundred dollars. My nephew made it a permanent part of his pool with it integrated into his pool pump and mounted on a wall next to his pool. Make sure you cover it when not in use from the rain. The best pool heater super efficient and effective. The hot tub I heat from cold.That intex heater eat electric and cant maintain the heat if you are in it. This heats the water and you can extend you soaking time all night if you want to. Enjoy building.

0
tvengineer
tvengineer

Reply 4 months ago

Thank you for the reply.... I am looking at a few different ones on Amazon.. I will be using it with the Intex 6 person (yea six little persons) spa.. Yes.. It does not maintain the heat when the bubbles are running.. and this is in the summer.. I imagine when the air is cold those bubbles will cool it down really fast. I like the idea that you let it cool and only heat it with the propane heater.. I don't know how much we would use it in cooler weather... and running the electric heater all the time once the temperature drops will be very expensive.. Knowing I can heat it in a couple of hours from cold means that I can keep it going without breaking the bank. Again thank you for the quick reply.. First thing is for me to build a small deck to put it on (it is in the mud right now) then I will buy the heater. :-)

0
ScottC189
ScottC189

Reply 8 months ago

How did you hook it on the hand truck?

0
jimrock66
jimrock66

Reply 8 months ago

This setup is very popular and the heaters are from amazon and the 18L per our can cost you just over $100 that can heat a pool rather quickly

0
jimrock66
jimrock66

Reply 8 months ago

I used these clamps

0
weber713
weber713

Reply 1 year ago

What a great idea to make it nice and portable!