Cheap pool heater

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sbmiller

sbmiller

0
LifeTime Supporter
Mar 20, 2013
19
DFW
Pool Size
10000
Surface
Plaster
Chlorine
Liquid Chlorine
Need some advice on how to heat my pool 10 degrees or less without spending $3,000. It doesn’t have to be fast, just effective. I do have a solar cover but the pool only gets 6-8 hours of sunlight per day. Not really wanting any kind of solar heater because they take up too much real estate. My daughter wants to have her sweet 16 at the house mid October and it’s usually ALMOST warm enough to swim at that time. Husband is open to DIY options as well but I’ve noticed plenty of fails after reading through the threads.
 
So….garden hose from the water heater was snark but then I started to wonder if it would work.

Your pool is only 10k gallons. Assume its 70 degrees and you want to get to 80. You’ll need 2500 gallons at 120 degrees to get the pool up 10 degrees. Thats 60 refills of a typical 40 gallon tank which is going to take a couple days to process never mind the heat loss back to the October air over the time period.

Never mind….don’t try the garden hose from the house 🤣
 
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Actually, in theory, yes, you could use a tankless water heater that run off LP, NG or electricity. All you have to do is install a few lines to the heater, source water (from pool) and one for the hot water into the pool. I know you can get them for say $500 for 4gpm. You'll want to enclose it since most units are not designed to be outdoors but it's doable and not $3000.
 
Well, 4 gpm makes it a 10 hour heat, not a couple days. I would do some real research on the safety of running it for 10 hours straight. I would guess thats well outside of the intended use.
 
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It was a suggestion, so here's another, get a bigger unit if it's time sensitive. In Canada, it isn't completely uncommon to run a furnace for 10+hrs. That's exactly what a tankless unit is in design. Instead of heating air, it's heating water. Same burner/exchanger systems.
 
Not much you can do without an expensive installation. To get 10°F your pool needs at least 1M BTUs of heat. A standard pool heater could do that in couple of hours.

Tankless water heaters are not designed to work with highly chlorinated and mineralized pool water. In theory it will work, but you’re going to wreck the heater doing it.

You could buy a couple of hundred feet of black, contractor grade garden hose and put the coils in the sunniest part of your yard. Putting them on some black painted plywood or foam insulation will help. Then run water through the coils using a small submersible pump , maybe 1/2 to 3/4 HP. You’ll need to cover the pool to retain the heat. Run it only during the day and shut off everything at night to keep the water still and covered.

Cheap but probably very slow.
 
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I know you said no solar but I saw a person on YouTube with a smallish 2×2 or 3x3 solar water heater and it was a dyi project. Basically was a wood plywood platform, black hosing, some wood framing and a small pump. In the video I believe he was getting about 100F out of it. Others said to box it in, paint the whole thing black and put a plexiglass window on it to get the water hotter.

I don't know how big a pool or if it actually works (youtuber said it worked great) but if it does work it is very compacr.
 
You need a lot of flow and surface area for solar to work and even more so considering OP says 6-8hrs a day and doesn't want to use it due to footprint. Be easier and more effective to boil a bunch of kettles/pots on the bbq and keep dumping it into the pool.
 
A pool heater is just a big tankless water heater. You could try a bunch of immersible water heaters on different circuits of the house that are gfci protected with solar cover on. It will take a long long long time though.
 

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Poolbreh said:
A pool heater is just a big tankless water heater. You could try a bunch of immersible water heaters on different circuits of the house that are gfci protected with solar cover on. It will take a long long long time though.
Click to expand...

Maybe soús vidè is the way to go -


Flow, heat and WiFi control all in a compact little package … and you can cook your steaks at the same time … WIN-WIN!!!
 
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JoyfulNoise said:
Maybe soús vidè is the way to go -


Flow, heat and WiFi control all in a compact little package … and you can cook your steaks at the same time … WIN-WIN!!!
Click to expand...

The Precision Pro version is 1200W at 12L/min. That’s 4,000 BTU/hr at 3 GPM!!!

So you only need 244 hours to get to 1M BTUs. In that time you’ll flow about 46,000 gallons of water through the unit which is about 4 turnovers …. Perfect!!!

Maybe buy 2 just to be on the safe side.
 
sbmiller said:
Need some advice on how to heat my pool 10 degrees or less without spending $3,000. It doesn’t have to be fast, just effective. I do have a solar cover but the pool only gets 6-8 hours of sunlight per day. Not really wanting any kind of solar heater because they take up too much real estate. My daughter wants to have her sweet 16 at the house mid October and it’s usually ALMOST warm enough to swim at that time. Husband is open to DIY options as well but I’ve noticed plenty of fails after reading through the threads.
Click to expand...
Cheap pool heater = oxymoron. You can't fight physics. It takes, as Joyful Noise said, about a million btus to gain the heat you ask for. A gas fired heater is small, but will do the job quickly at a large cost. A heat pump is slightly larger, cost twice as much, and will do the job a bit slower but for less cost. Of course, installation charges have to be figured in as well.

Any size residential tankless heater that might do the job would cost as much as a heater designed for pool use and be destroyed by running pool water (very nasty stuff, actually) through it. Raypak makes an 11kw electric pool heater (a tankless heater) that I have seen ones try to heat a pool with. Same cost as a gas-fired heater, 92k btu per hour input (about 75k into the water).

Or, you get a large array of solar panels to get the heat into the pool faster than the heat loss. You would need many sunny days and a good insulating cover.
 
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I’m surprised your solar cover with 6-8 hours of sunlight won’t do it in the DFW climate. Granted, by mid-October, temps are cooler, but certainly not cold. We have a heater but have only used it for the spa - never the entire pool. We’ve been swimming in October before, but we had a warm spell.
 
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Poolbreh said:
2000W Immersion Pool Water Heater, Electric Submersible Instant Water Heater with Metal Guard Cover Portable Bucket Heater Heats 5 Gallons of Water in Minutes for Bathtub… (Black)
2000W Immersion Pool Water Heater, Electric Submersible Instant Water Heater with Metal Guard Cover Portable Bucket Heater Heats 5 Gallons of Water in Minutes for Bathtub… (Black) - - Amazon.com
Click to expand...

I can totally envision a bunch of shivering teenage kids all crowding around the immersion heater fighting and shoving each other over who gets to stand the closest to it ... :ROFLMAO:
 
I mean, how cheap is cheap ? For around $600-800, you can get small(ish) Electric pool heaters designed for above-ground pools/Spas, about 10-11Kw (35,000BTUs) - would probably do the job for a one-off sort of thing, but certainly wouldn't be 'efficient' or sustainable. You can get propane based ones (100K BTU) for around 1000-1500...

Using others numbers, you need 1M BTU assuming no outside heating (solar etc). Then you have to figure out what it takes to KEEP it there, or how much you LOSE every day. Rough estimate is about 5BTU per sqft per degree of difference. You don't say how big the pool is, but assuming 10,000 gallon, thats about 21f't diameter, so 10.5^2 = 110 * 3.14 = approx 350sq ft. Average DFW temp spread in October is 80-60F, so assuming you want to maintain 80 in the pool, call the 'average ambient' 70, so 10F to maintain...

So, roughly 5 x 350 x 10 = 17,500 BTU to HOLD the temp, once you get it UP to temp. 35kBTU would mean you were essentially heating at 17k/hr, maybe a little more depending... so roughly 40-60 hours without any outside help. Then it'd be running fairly hard to keep it there...but in theory, it'd work. So many variables, anything 'precise' is going to be impossible...Ambient temp, how windy it is, how fast the water runs, efficiency of the heater...etc etc etc. Your mileage will almost certainly NOT be what you planned ;)

Say 60 hours at 10Kw at $0.15/kw = $90...maybe you could sell the heater at the end...

Disclaimer : I failed math, and there is no Holiday Inn locally for me to have stayed in last night !
 
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