Tankless Water Heater to Heat My Pool

AndyTN

Bronze Supporter
Mar 27, 2019
91
Memphis
Don't worry too much for the criticism. There are many really stupid ideas of how to heat pool water just by searching "redneck pool heater" and the attached picture is a hilarious example. At least you are taking the time to really think this through.

I think everyone is a bit concerned seeing a gas heater mounted directly to the side of a wood deck. As a contingency plan, if the wood deck catches on fire, it will melt the vinyl wall of your pool instantly dumping thousands of gallons of water on your burning deck to extinguish the flames.
 

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stewbets

Active member
Apr 22, 2019
32
Dayton. OH
Don't worry too much for the criticism. There are many really stupid ideas of how to heat pool water just by searching "redneck pool heater" and the attached picture is a hilarious example. At least you are taking the time to really think this through.

I think everyone is a bit concerned seeing a gas heater mounted directly to the side of a wood deck. As a contingency plan, if the wood deck catches on fire, it will melt the vinyl wall of your pool instantly dumping thousands of gallons of water on your burning deck to extinguish the flames.
Ha! I like your contingency plan! And while I agree that my vent pipe is not sufficient, I revealed that picture after all the flaming and there's nothing else inherently dangerous about what I've done. All appliances fail at some point. The crazy thing is that this heater is designed to be installed (and eventually fail) INSIDE YOUR HOUSE! Talk about dangerous (sarcasm)!

I do think I have a different definition of what constitutes a stupid idea. I personally love the effort demonstrated in the picture you posted. Sure it's not refined, and it may not have been executed properly either, but somebody set out to solve a problem with ingenuity and creativity. And I'll bet they enjoyed the process. To me, there's nothing more ignorant than pouring money you don't have into your hobby. That's what I would call a stupid idea. But often you can't see those ideas because you don't know people's financial situations and the stress their decisions are causing. I've got 5 kids and a fairly modest salary. My wife is a full-time mom and teacher of our children. We do a good bit of thinking outside of the box in order to make things work and we love it! In fact, we wouldn't have it any other way.
 
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AndyTN

Bronze Supporter
Mar 27, 2019
91
Memphis
Ha! I like your contingency plan! And while I agree that my vent pipe is not sufficient, I revealed that picture after all the flaming and there's nothing else inherently dangerous about what I've done. All appliances fail at some point. The crazy thing is that this heater is designed to be installed (and eventually fail) INSIDE YOUR HOUSE! Talk about dangerous (sarcasm)!

I do think I have a different definition of what constitutes a stupid idea. I personally love the effort demonstrated in the picture you posted. Sure it's not refined, and it may not have been executed properly either, but somebody set out to solve a problem with ingenuity and creativity. And I'll bet they enjoyed the process. To me, there's nothing more ignorant than pouring money you don't have into your hobby. That's what I would call a stupid idea. But often you can't see those ideas because you don't know people's financial situations and the stress their decisions are causing. I've got 5 kids and a fairly modest salary. My wife is a full-time mom and teacher of our children. We do a good bit of thinking outside of the box in order to make things work and we love it! In fact, we wouldn't have it any other way.
I get what you mean. I don't want to invest in a $2000-4000 heater when by the time June rolls around, it is so hot in Memphis that I am trying to cool off my water rather than heat it. Every April, I get excited about the warm weather and end up draining 25% of my pool water to then fill it back up with hot water from my main water heater in my attic. I have to run the water very slowly through a 1/4 vinyl hose so it takes about 3 days to fill. My wife gets very annoyed every time I do it but it ends up increasing the water temp by 10-15 degrees making it swimable for the kids and me (not my wife). I get a warmer pool with no new equipment and get a month's head start on my pool but a slightly higher electric bill. I of course do this while keeping the solar cover on the whole time.
 

cfherrman

TFP Guide
May 10, 2017
2,239
Hays, Kansas
Just one or two more sections of vent pipe and i wouldn't worry about it. I'm more concerned about people getting burns from the vent pipe or the gasses then anything else about it.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,001
Tucson, AZ
I get what you mean. I don't want to invest in a $2000-4000 heater when by the time June rolls around, it is so hot in Memphis that I am trying to cool off my water rather than heat it. Every April, I get excited about the warm weather and end up draining 25% of my pool water to then fill it back up with hot water from my main water heater in my attic. I have to run the water very slowly through a 1/4 vinyl hose so it takes about 3 days to fill. My wife gets very annoyed every time I do it but it ends up increasing the water temp by 10-15 degrees making it swimable for the kids and me (not my wife). I get a warmer pool with no new equipment and get a month's head start on my pool but a slightly higher electric bill. I of course do this while keeping the solar cover on the whole time.
This is where a pool solar heater is great, although admittedly costly up front. Add heat for free in the spring and fall. And if you run in the summer at night it will cool your pool also.
 

stewbets

Active member
Apr 22, 2019
32
Dayton. OH
Thought I'd post a little update on the setup. Things are still going... swimmingly. See what I did there? We had the water at 85 degrees this weekend for a party of 15 cousins and the pool survived! The last thing I had in mind to add to my heater setup was some kind of WiFi control. I finally found the inexpensive solution I've been looking for and set it up last week. I purchased a Sonoff TH10. It works really well and is so much more convenient than manually adjusting the thermostat or checking the temperature. My only gripes with it is that the temperature precision is low and it also reads 2 degrees lower than my other thermometers. The unit is based on Celsuis and does not display decimals. It can be set for Fahrenheit, but the temperature increases or decreases by two's since it's simply taking the Celsius reading and converting it. This would be such a simple thing to correct by the manufacturer with a firmware update, but it doesn't look like that's going to happen. However, there is custom firware out there that unlocks decimal precision and I may experiment with that in the near future.

That probably sounded more negative than positive, but I do really like this setup. I just wanted to give realistic expectations. I also bought one of their basic switches and connected it to my pump to make it easier to turn on and off for vacuuming and other maintenance. I'll share the Amazon links to these products, though they can be purchased for much cheaper through eBay (directly from China):

Sonoff TH10 Thermostat - Amazon.com: Sonoff Remote Home Temperature and Humidity Monitoring WiFi Smart Switch for Home Automation System,Works with Alexa&Google Assistant (Sonoff TH10): Home Improvement

Sonoff Temperature Sensor - Amazon.com: Sonoff Waterproof Temperature Sensor DS18B20, Work with Wi-Fi Wireless Remote Temperature Sensor Smart Switch (Sonoff TH10/TH16: Home Improvement

Sonoff WiFi Switch - Sonoff WiFi Switch Pack of 2 Wireless Remote Control Electrical for Household Appliances Compatible with Alexa DIY Your Home via Iphone Android App - - Amazon.com

I've also attached a couple screenshots of what the mobile app looks like. I don't know if everyone else keeps their temperature constant, but I like to let mine go if the forecast does not look favorable for several days. That's a huge reason why I value remote control.
 

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Vickery

Gold Supporter
Silver Supporter
Feb 22, 2009
418
Perfection, NC
A few years ago (okay, more than a few. It just seems like a few.) Home builders were using tankless heaters to provide both domestic hot water and circulated it through a coil for apartment heating. Granted, the chemistry was potable water but it actually worked. Heater life wasn't as great as a furnace but it was a lot less expensive to install.
 

Divin Dave

TFP Expert
LifeTime Supporter
Oct 2, 2013
5,456
Longview, Texas
Hi Stew,
I just wanna say Im digging your heater experiment. Ive often given more than a thought or 2 of somehow using a tankless water heater too,... Keep us posted!
 

stewbets

Active member
Apr 22, 2019
32
Dayton. OH
A few years ago (okay, more than a few. It just seems like a few.) Home builders were using tankless heaters to provide both domestic hot water and circulated it through a coil for apartment heating. Granted, the chemistry was potable water but it actually worked. Heater life wasn't as great as a furnace but it was a lot less expensive to install.
Yeah, heater life is still the big question mark here. If it makes it through a swimming season, I think I'm good. This heater is small and under $100, so replacing it is not a big deal when the time comes, as long as that time doesn't come too quickly.
 

stewbets

Active member
Apr 22, 2019
32
Dayton. OH
Hi Stew,
I just wanna say Im digging your heater experiment. Ive often given more than a thought or 2 of somehow using a tankless water heater too,... Keep us posted!
Thanks! I plan on posting the good and the bad of this project and how it fares in the long run. I wouldn't want to leave anyone hanging!
 

Vickery

Gold Supporter
Silver Supporter
Feb 22, 2009
418
Perfection, NC
The other concern is that the life of the heater is directly related to the amount of copper leached from the heat exchanger into the pool water.
 

stewbets

Active member
Apr 22, 2019
32
Dayton. OH
We used the pool for the first time in a little while yesterday. It has been rainy and cooler around here. I turned the heater on at 9:00 AM when the water temp was 77 degrees and by 5:00 PM it was 86 degrees. I continue to be pleased by the performance of this setup. And having the ability to turn the heater or pump on and off from my phone makes it so much more convenient.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,001
Tucson, AZ
We used the pool for the first time in a little while yesterday. It has been rainy and cooler around here. I turned the heater on at 9:00 AM when the water temp was 77 degrees and by 5:00 PM it was 86 degrees. I continue to be pleased by the performance of this setup. And having the ability to turn the heater or pump on and off from my phone makes it so much more convenient.
The sun alone likely added a majority of that. Would be curious for you to report temperatures when the heat eased not run.
 

stewbets

Active member
Apr 22, 2019
32
Dayton. OH
The sun alone likely added a majority of that. Would be curious for you to report temperatures when the heat eased not run.
I'm not getting Arizona sun up here ;). I've mentioned earlier that the sun is contributing, but as far as it being the main contributor? I don't think so. The energy I'm putting into the water is enough to raise it a little more than 2/3 of a degree an hour, or 5-1/2 degrees in 8 hours. That would leave the sun responsible for 3-1/2 degrees. I do like your idea of checking the temps in the morning and evening without the use of a heater. Doing this a few days could give me a decent baseline.
 
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