Thinking of a DIY heater with a black hose

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richierich

Bronze Supporter
Jul 12, 2013
748
Long Island, NY
Hi All -

I saw some videos of people using like a 100 foot black hose laid out in the sun and using a submersive pump to circulate the pool water from the pool, around the hose and back into the pool for say 5 mins at a time. Then letting it heat up and do the same thing a few times a day.

Has anyone tried doing that?

I also saw people doing the same thing with poly black hose and using hose clamps to connect to a garden hose and a sump pump.

Thoughts/ideas/suggestions? Thanks

I'm not very handy at all and my intex pool is one of those small pump ones with the 1 1/4 hoses that go into the pool.
 
Cycling the pump is also not the way to solar heat. It may seem counter intuitive, but a constant flow will produce more BTU's/hr into the water than letting the hose warm up and then purging it. As the water gets warmer in the hose the thermal transfer efficiency drops off. There has been several discussions on this over the years on the forums about this.
 
And solar heating is about exposed area. The hose you are talking about is only around 10sqft exposed to the sun. I have 500 sqft of solar panels.

I doubt that hose would make a noticeable difference unless the pool is very small.
 
If I read his signature correctly from my phone, we are talking a small 3500 gallon pool. What he is thinking of may indeed make an impact.

Regardless of impact or not, one of these homemade hacks is the first step many take before starting to get serious with more efficient commercial systems. I encourage the experimentation. That's how I got started. :)

Yes, there is no need to stop the pump for the pipe to heat back up, but you don't want it running when the sun is not hitting it or you could actually cool the pool.

Sent from my Nexus 4 using Tapatalk
 
Well, solar is usually sized relative to the surface area of the pool ... usually wanting at least 50% of the surface area of the pool in solar area. The pool here is 150sqft ... so that hose will be 7% of the surface area.

Lets assume that the hose will provide 1000 BTUs/sqft/day (likely optimistic as that is what true solar panels achieve). That means the hose will add ~10,000 BTUs per day.
3500 gallons = 29,000 pounds of water
It takes 1BTU to raise 1 pound of water by 1 degree F.

So ... 10000 BTUs / 29000 pounds ... means that the hose will raise the pool's temperature by about 1/3 degree F each day ... neglecting loses and using an overly optimistic rate of heat transfer.

Using a solar cover to retain heat (especially at night) will do more than the hose will.
 
One of the things I learned from my own experimentation is a great respect for how much heat is really needed to heat a pool.

I started with a $50 irrigation tube hack, but the (very) hot water flowing from that hack eventually led me to invest in a commercial system.

Thanks for doing the math, awesome post. Regardless, I think he should try it, unless he is willing to invest in a commercial panel or two, which I would also suggest.

Sent from my Nexus 4 using Tapatalk
 
I am all for experimentation as much as the next guy and as I said above if you already have all the stuff on hand why not, but the math shows this is NOT going to make much difference, what it may do is provide a trickle of warm water at the returns that someone could huddle around like a camp fire to get a little warmer in a cold pool. Rather than spending money to build something like this a person would be far better off adding one of the prebuilt solar heater kits, even one of the cheap $100-$140 2x20 kits would give 4 times the heat that this home made system could.

Ike
 
Thanks for the replies......... What sort of panels that are cheap would you folks recommend. Remember, I don't have a "real" above ground pool. Its a small 14' intex pool with the 1.25" hoses going from the pool, into the pump and back into the pool. So some options you may suggest for an AGP may not apply.

Would using my sump pump work as an option or is it better to run through the pool pump filter. I was figuring the pump would be better so I can shut it off once the hot air and water is done flowing.

Also, how would you secure the panels to the roof I don't want a hole in my roof, as stated earlier I'm not very handy
 
What size pump do you have ?? Putting the coil up on the roof can be a pretty big burden on your pools pump if it's sized for you rather small pool. When you say roof, is it one story or two ?? How high do you need to lift the water ?? Any chance you have some place on the ground you can put the coil(s) ?? If it was on the ground and you put cheap black patio pavers down first it would be similar to having them on a black roof but it would bank a bit more heat between clouds and give you a little more in the evening. It would also be so much easier on your pump.
 

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I would also suggest starting off with a solar cover. Most of the above ground solar panel kits are designed for seasonal use and to be installed on the ground or on an angled near ground level mounting rack. Some popular choices are the Fafco Bear systems and Eco Saver above ground kit sold by Amazon. From what I have read both seem to be fairly decent kits for the price point, my big complaint about them and most others like them is that the installation instructions have been dumbed down to the point of skipping over much potentially important information, with the Fafco Bear systems it has been turned into a cartoon that a first grader could understand. They leave out such important points as telling people that a properly functioning solar panel should feel relatively cool to the touch and that the return water should only be slightly warmer than the pool water, not HOT. Hot return water implies lack of water flow through the panels (often due to too small of pump), there is not even a water flow diagram of the complete system in the manual, just close ups of connect hose A to inlet A, etc.

Ike

p.s. you tube is a great source or information on solar panel installs, both showing the right and the wrong way to do things
 
I made one using plywood, 2x4s, black spray paint, and black HD garden hoses that my wife found somewhere on Pinterest or something. This link and image gives you the idea of how it all comes together, to a degree. http://www.ehow.com/how_5140256_build-passive-solar-pool-heater.html

This pic is what mine looks very similar to. I have seen guys cover it with Plexi-glass to retain heat, but I haven't done that to date. pool heater pic.jpg

We are in WI, so in addition to needing a good solar cover, a gas/electric/propane/etc. heater is almost a necessity to make a pool worthwhile here. We had a lousy old inefficient Hayward Propane heater that I pulled off site when we bought the house (w/ pool). The solar cover they had was on it's last legs, so we purchased a clear thick 16 mil new solar cover, which has proven to be one of my best expenses to date. It blows any blue one I've ever owned or seen out of the water, no pun intended.

I put a tee in my pool return line with a PVC shut off valve after the tee. Necked down the bottom outlet fitting (3rd leg) of the tee to a 3/4" hose thread and I feather the valve to steer enough of the water out thru the tee to my coiled up heater to push water at a slow rate and into the pool....but only when I plan on utilizing the heating feature. Pressure gauge on the pump jumps to about 7-8 psi but still leaving a good amount of water coming thru the return. Isaac's discussion above I assume revolves around a system that is working ANY time the pump system is on...I didn't want that for a variety of reasons, so I have the passive set-up that I can control. I own a 28' round Doughboy Tuscany that happens to have the waterfall feature, so the heated water enters the pool thru that fitting under the rail and out thru the waterfall and not from an ugly hose hanging over the edge of the pool in plain sight. Every day with full sun from pool opener thru the summer, we have a timer that will turn the pump on at 11 AM and then run for 30 minutes and then again at 2 PM and run for another 30 minutes. I can't stress how warm that water is that comes out of there, and I should measure it with a thermometer but you can hardly touch it when it trickles into the pool. Not sure what the weekly or daily gains are, but I know it has helped dramatically versus using just the solar cover. You've all felt water coming out of a hose that laid in your yard in the sun for a good bit and how hot the water is right after you turn it on...same results/same principle.

With that, I plan on revising this thing next year and utilizing 1/2" black irrigation line to replace the 3 x 50' black garden hoses. I'll have more surface area for water heating versus a 5/8" HD rubber hose...(there will be no kinks in this material as the hose always gets a kink somewhere, if not more than one spot, and this effects water pressure and efficiency.) It also weighs about a 10th of what the assembly with garden hoses weighs (when empty) for storing this unit in the winter months. I added 2 lawnmower wheels on mine last year to move it and transport it. Also note....depending on where you live, each months has a different relative angle from your location to the sun, based on the angle to Earth, so if you plan on putting it on the ground and not on your roof, keep that in mind. You can find that info right here: http://www.gogreensolar.com/pages/solar-panel-tilt-calculator

Worth noting that if you store something like this in the winter months and you live in a cold climate, you need to use an air compressor to blow out most, if not all, of the water out of the lines to avoid rupture issues.
 
Ok, just a couple of things about your setup, to get maximum heat into your pool you want the return flow from the solar heater AS COOL as possible, ideally only a degree or two warmer than the pool water. As it is FAR BETTER to heat a lot of water just a little bit, than a little water a lot. So your goal here should not be trying to make the return water as hot as possible by lowering the total flow, instead it should be to transfer the most BTU's into the pool itself. Aiming for peak water temperature at low flow may be a valid concern when using solar heaters for domestic hot water, but that is not what we are talking about here, we are talking about heating a swimming pool. Also you mention people using a glazed box with coils for heating water, this again increases peak temperature, but it REDUCES total BTU's available if the air temperature is within about 20 degrees of the desired water temperature. I know this does not make common sense, but look at it this way, solar heating is all about absorbing heat from the sun into the water, in this case it is about heating the pool water. If you take a set of hoses that place them in a black box as you have done, you do get a bit more conductive heat from the black surface to the back side of the hose. Now if you were to add a glass "greenhouse" in an attempt to trap heat in the box, here is what happens:

For easy math, lets pretend there are 100 units of light/heat in your sunlight, and you have a glass covered box with a water hose inside.

The first thing that happens is the light hits the glass, and about 15% of it is reflected, so right off the bat we are down to 85 units of light getting to the box. Then most of the non visible spectrum (IR, UV ) that accounts for over 50% of sunlight does make it through the glass, instead that non visible light gets absorbed by the glass itself, then re-radiated, about half going inside the box and half outside. So of that remaining 85 units of light (visible and non-visible) about 40 units of the non-visible part are absorbed by the glass, 20 are reradiated back into the air and 20 go into the box. The net effect is your 85 units of light become 65 going into the box. So by adding a glass panel to your box you end up reducing the total available heating by 35%, of course at the same time you do a better job of trapping the heat in the box, but again this is not our goal, our goal is to heat the pool, not make a box hot. So we are back to the fact you are better off not glazing the box and have higher water flow unless the air temperature is low enough to suck more than 35% of the heat out of the tubes, which typically happens with about a 20 degree F temperature difference ( a bit less if you have high winds)
 
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