Pool heating

Gordy1

I was looking for input on a different sort of pool heating.In a above ground pool if one used a bed of 2" foam then pex, Dia and spacing yet to be decided. Then 4" of sand, liner pad then liner.Would this be a feasible or efficient way to heat a 24'round pool? My thinking would be elimination of a HX, and this method would not depend on pool pump operation to circulate the heated water. Maybe someone out there has thought of or used this method.
Gordy

[Deleted User]

Heat loss / forget the sand

Get some numbers for heat loss togther. A Solar cover will stop about 70% of heat losss through evaporation. Don't put the tubes in sand, put them in a grout, sand and cement mixture. In ground vinyl pools all have a grout bottom. Just as in a house, putting the heat in the floor of the pool is the most efficient. You will love this system...

jp_2

heck, put'em at the bottom

consider putting them at the bottom of the pool(inside-false bottom), would be your best bet. off hand, I doubt this would work in any way,shape or fashion, just too much mass(water) to heat effectively from a couple hundred feet of pex. insulating the perimeter is a good idea though.

Weezbo

Bag the sand straight from the gate.

there is much btu's to pump into the pool,as the mass will drink it up however,given time it will make a dent and after that may be it is poifect for a sundays work:) The pool cover that was mentioned is a hep idea.makes a water sandwich

Robert O'Connor_7

Maybe?

Maybe if you rapped the tube around the outside too it would take the edge off (I doubt it) but having it heavily insulated bottom & sides with NO spacing and running a very high temp just might.?? I like the the way your thinking though, keep the wheels turning...Robert O'Connor/NJ

Mike T., Swampeast MO

Some Quick Calculations

Approximate tube lengths for a spiral in a 24' diameter pool:

8" spacing -- 1,392'

6" spacing -- 1,845'

4" spacing -- 2,748'

3" spacing -- 3,652'

If pool averages 4' deep it holds about 112,600 pounds of water @ 82°.

Using the 4" spacing, if you used 200' runs you would have about 13 loops. Flow 1 gpm through each for a total of 13 gpm.

IF you can achieve a 30° delta-t in each loop AND all of the heat is going to the water, you'd be transferring about 195,000 btu/hr to the pool water. With delta-t of 20° output is about 130,000 btu/hr.

Even uncovered, that's [probably] enough heat with any reasonable temp rise--say 25° or so.

1¼" supply/return manifolds run radially in the pool circle would [seem] a good way and also really easy to get reverse-return by connecting the boiler to the manifolds from opposite ends.

Mike T., Swampeast MO

ERROR! ERROR! ERROR!

Above tube lengths are WRONG! I was just using diameter(dia * pi) for calculating the spiral and when I decremented the diameter I subtracted the radius!!!! So, numbers are right at 2X too long!

8" spacing: 716'

6" spacing: 942'

4" spacing: 1,392'

3" spacing: 1,845'

Heat outputs will be similary overstated (nearly 2X). Sorry! Maybe if you keep the pool covered to stop the evaporation loss and only expect to have it useful a month or so before "normal"?

jp_2

so then, whats the cost of 1,400ft of pex & manifolds compared to a 150kbtu heat exchanger?

Gordy1

Thanks for all your replies! I guess I should share what my expectations are for the system.While I do not wish to ramp up the pool in a matter of hours from 60* or have it 100*. My scenerio would be as follows.Upon opening in the spring mid May the temp. is 60*. I use a solar blanket and in a week weather dependent we are low 70's.So with that in mind I would pickup with the heat from that point. Mid to upper 80's is target temp.So I'm looking at a 15* to 20* rise at most.So I'm not really looking for opening at the beginnig of may or staying open until the end of Sept or Oct.I merrily want to enhance its present state.

I don't have room for the number of solar panels needed. Everyone I know who has the conventional gas pool heaters have had problems in a few years with them, about when the warranty is up.I already have a 150,000 Btu boiler for the house,does not make much sense to me to buy another one.Could go with an HX off of that but then the pool pump has to run to circulate the heated water,I would rather use the 1/12hp B&G series 100 HV circulator I already have to do the circulating, rather than a 1.5 HP pool pump since I really only need to run the pool pump 4 hrs a day.

Mike Swampest your first calcs. on tubing lengths are right Pi x dia = Circumference. I discounted the outer foot and used 23'as the starting dia. Came up with 1726' at 6" o.c. I used 113000# of water.Using 452 ft2 of pool area thats 250# of water a square foot to raise that 20* would take 5452 Btu hrs. ft2,or 2,260,000 for the whole pool. Using the 23' dia to calculate usable area for tubing which would be 415 sqft. (staying in from the outer edge 1').Sooo 113 Btu's per hour would take 48hours to do this, 5452 btu / 48 hrs. If I used 6 loops of 3/4 inch barrior pex at 300' each and a supply temp of 120*-150* is this possible? I know the boiler I have can deliver the Btu's and I,m setup with 1 1/4 supply line stubbed already and that can carry the btu's needed.Since I have acquainted myself with copper because that is what my home has for radiant I really don't know what pex is capable of for delivery I assume they are close to one another.

Sometimes one has a hard time letting go of an idea thinking its a good one, only to be a bad one.Is this one? Hell I'd like to do it just to do it and see the results.Have not seen this method of pool heating yet.Drain the pool get the Pex lash it up yah.

Dave_22

Here's something....

I am trying this with my pool (not my picture, but same principle). I got the dish for free and have 150' of black hose connected. I am using a 15-42 pump instead of using a big 1Hp pool pump. I may use a timer with a photocell, so it only runs during the day and in sunlight. It may take awhile to heat, but I'm not looking for speed, just a few more degrees!!!!

Gordy1

Gordy1

Nice one Dave. will the dish track the optimum sun angle? If not you could make it so it did.Let me know the out come.Add some High sheen tin to the back and leave a little space between the tubing to heat the back side. My Wife says I'm pre-occupied,I see I'm not the only one around here.

Dave_22

Yes

Good call on the back side. I was thinking about putting half inch silver foam behind it- it would be a little harder to fasten because I was going to use wire ties. Yes, I thought about a few different ways to track the sun. One was with a "bump" timer that bumps the motor intermittently throughout the day. Then an end switch that would send it back to "home" at the end of the day. Probably be quicker to buy one, but what fun is that!!!!

Mike T., Swampeast MO

First tube calcs really aren't right! Watch out!!!! pi * diameter is a shorthand for 2 * pi * r BUT...

If you're doing a simple calculation (not a true spiral but just concentric circles) and you use the diameter (not the radius) you MUST subtract TWICE your tube spacing!!!! If you don't, you're cutting the tube spacing in half!!!

That was the error---either use radius for calculating or double your spacing if using diameter.

Gordy1

Backside

> Good call on the back side. I was thinking about

> putting half inch silver foam behind it- it would

> be a little harder to fasten because I was going

> to use wire ties. Yes, I thought about a few

> different ways to track the sun. One was with a

> "bump" timer that bumps the motor intermittently

> throughout the day. Then an end switch that would

> send it back to "home" at the end of the day.

> Probably be quicker to buy one, but what fun is

> that!!!!

Robert O'Connor_7

Is that...

Is that the future of HVACtv? Sending data with Hydronics. I like it, COOL.(I mean HOT) Robert O'Connor/NJ

Mark Eatherton1

Why...

that a focusing constipator ain't it? Hain't seen one of them in a goats life!:-0

Does it track the sun???

ME

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Gordy1

Mike

I found this formula 2*pi*r*n= spiral length. R is radius of spiral.N is the number of spiral turns in the radius.

using 11' as fillable radius for tubing,this is what I get.
3041'for 3"
2280'for 4"
1452'for 6"
1140'for 8"
760'for 1'

Gordy1

Dave

> Good call on the back side. I was thinking about

> putting half inch silver foam behind it- it would

> be a little harder to fasten because I was going

> to use wire ties. Yes, I thought about a few

> different ways to track the sun. One was with a

> "bump" timer that bumps the motor intermittently

> throughout the day. Then an end switch that would

> send it back to "home" at the end of the day.

> Probably be quicker to buy one, but what fun is

> that!!!!

Gordy1

Dave

What size tubing is that? Yes celotex or R-foil or sheet metal "cat on a hot tin roof".Remember mother nature, rain and wind though,I don't know the wind scenario in your area.Throw a giant magnifying glass on her you got steam drive.Dave do me a favor check my formula below 2*Pi*r*N=spiral length.If you measure the radius of the tubing covered area only on your dish and count the number of wraps in the radius. Plug them into the formula, and that should give you your tubing length.

leo g_13

that is beyond kewl!

hfree heating AND better television reception!

Leo G

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