Programming Challenge 1/22 - Passive Solar Pool Heater

[john.uhden]

Alrighty Guys and Gals,

We here in the northern hemisphere have passed our winter solstice so the days are getting longer.  Summer is on its way, which seems to be an annual event.

That means it won't be long until your spouse says it's time to open the pool.  At my house that's usually April 30 or May 1.  While my wife will submerge herself immediately after the first vacuuming, I won't go in above my waist until the water temperature is at least 76°F, which in Monmouth County, New Jersey means about the middle of June.  So if this thing can raise my water temperature just 1° per day, then I might be able to take my first Nestea Plunge before Memorial Day.

I refuse to spend any money on a fuel powered heater, but I've had this idea for a long time of building a passive solar heater.  All you need is some poly pipe, a little plywood, and a Little Giant cover pump (which I already have).

Now materials and dimensions may vary from country to country, but my idea is to lay out a 100 foot coil of 1" poly  pipe on a half sheet of 3/8" to 1/2" plywood with gaps between orbits of about 1/4" to provide for drill holes and zip ties to attach the pipe to the plywood.  The idea is to provide one or more hinged legs on the rear of the assembly to direct the face at the proper horizontal and vertical angle to the sun as the season progresses.

Ergo, your challenge is to write an AutoLisp (including VLisp) function to create the coil design subject to the following rules:

1.  You must check the applicable pipe standards to determine the standard pipe O.D.  I'm talking about piping that would be used for a yard irrigation system.

2.  You may use any unit of measurement which is comfortable to you.

3.  You may not use an initial internal radius of curvature less than 10 inches at the centerline of the pipe lest it might create a kink in the pipe.

4.  You must try to use exactly 100 feet of pipe (or 30 meters or whatever) because couplings are not permitted except at each end for getting piping from the pump and back into the pool.  The outward limit is where the side of the end of the pipe intersects an edge of the plywood.

5.  You must provide only one (1) vertex per quadrant (NE, NW, SW, SE) which will happen to be where the holes will be drilled.  Also that will avoid placing holes near the edge of the plywood.  Your arced segments need not be exact because the radius is changing infinitely, but the result should appear to be exact.  Your poolyline should be drawn at a constant width equal to the pipe O.D.

6.  You may use trial and error to alter the gap size only slightly to have the outer terminus end as described in rule #4.  It would be better not to have any excess pipe that has to be trimmed off.

7.  Include in your drawing the actual dimensions used and the resulting length.  Mtext will be satisfactory because creating a table is just too much code.

Okay everybody, DIVE IN!!  Let's say that we want this submitted before the end of January, which will give you enough time after the Superball and March Madness to actually build your contraption before opening day.

Extra credit goes to any thermodynamically inclined soul who can determine the rate of temperature increase for a 25,000 gallon pool based on average daylight times and conditions. and the flow capacity of the pump.  I have no idea whether it makes any difference if the pool is inground or above ground.  Do not include your analysis in the drawing but just in your response.

Refer any questions to @ronjonp or @hak_vz or @Anonymous because I may not understand them.

[Sea-Haven]

OH NO 😆

[john.uhden]

@ronjonp
Sure looks like my pump.
Mine has a 1" threaded male discharge with an adapter to garden hose size.

[john.uhden]

@Sea-Haven,
I am not putting this thing on my garage roof. It will sit on the pool
deck, 6" above the water surface. Nor am I worried about pressure, high or
low.
I have used the pump to create a spewing fountain that my eldest
granddaughter loved. My idea was to cool the pool. I think it had a
negligible effect, but it was fun.

[Sea-Haven]

Thought height might be problem but if at similar level a low pressure pump should be fine. I had a submersible for my spa as no drain, but it pumped like 4 litres/second out of a 1" so could blow hose connections.

I expect your pool has a decent pump have you looked a tee arrangement ? Connect off return after filter, I did something similar for a rain tank as my sub pump was to powerful for irrigation 1/2" so had a blow off return valve to tank just got balance right blow off v's garden no hose disconnects. So 2 valves pool or heater. Even open both. 

[john.uhden]

<ROFLOL>

That's what you get for using those aftermarket Aussie products.  😁

Either that or you didn't heed my specs of no couplings.  Ya know you have to use band clamps with them, and tighten them too.  Have you fed your wallabies lately?

But I'm very proud of your expanding your animations from blinking to squirting.

[john.uhden]

@Sea-Haven 

Definitely not.  Too much work.  Too much 1-1/2" piping and elbows, and solvent, etc.  And something to trip over and bang my head on the concrete.

Just plunk the Little Giant into the pool and plug it in.  I have an extra outlet nearby.

Ya know, back when the kids were kids, I decided to show off, and we had a diving board.  So I got way back behind it and ran to get a giant launch into the pool.  But my foot caught the land end of the board and I did a face plant.  I guess it was very funny, but my bloody (literally) face disagreed.

[Scottu2]

Hello John,

This is an interesting challenge, cool (warm) beans... some line from an old movie I cannot remember.

I realize this is a Lisp programing challenge, but just a few side questions.

Is there a concerned about the weather during Dec, Jan, Feb, and Mar freezing the water in the pipes?

Also, for safety is the Little Giant pump a 1" sump pump at 24Vdc?

Perhaps an external Magnetic Drive on a GFCI outlet would be safer?

Is there sufficient room to expand from 1 panel to 4 panels on the deck?

[john.uhden]

@Scottu2 

Yes, there is a concern for winter months.  Good point.

But I can blow it out at pool closing time with my Hoover PortaPower vacuum/blower.  I use it to blow out my 1-1/2" pool piping.  It produces more pressure than my ShopVac.

The Little Giant cover pump uses regular 110V house power.  It has a 1" discharge and an adapter for connecting a garden hose.

I despise GFCI outlets.  I run extension cords from my garage for the the outside Christmas lights in order to avoid the GFCIs my electrician said I had to install.  BTW, the Woods 50009 digital timers are great!  I can have the two separate circuits on each side of my house come on within 5 secs. of each other, every day.  Mechanical timers are for horse manure.  Oh yeah... I can use one of the timers for the pump.  YAY!

Yes, there is plenty of room on the pool deck, up to the point when my wife says, "NO MORE!"

[Kent1Cooper]

Give this a shot.

It has a few divergences from your original description.

In order to accommodate the potential users described in Message 20, it asks the User for the size of the panel [and center point, and draws it, as a square], the pipe O.D. and bending radius and overall roll length, and both a desired gap between passes and a minimum allowable gap in case it needs to be squeezed down to get more length in.

Since it rounds all corners at the same radius [see Message 15], it doesn't use one vertex per quadrant, but one line segment per quadrant between rounded corners [except for the initial 3/4-turn arc segment].  The same-radius bends not only get more length in than a "plain" spiral of the same number of loops, but also greatly simplify the drawing of it -- the coil is drawn first without the bends [far fewer vertices, and so much easier to locate them], and Fillet's Polyline option curves all the corners at once.

It doesn't put in any Text/Mtext reporting [but that can be added easily enough].  But it does report to you at the command line if the total roll length doesn't fit on the panel under current settings.

In addition:

It doesn't need to deal with visibility, because it doesn't try drawing something and check the result, and try again with adjustments.  It calculates the length it can fit on the panel under current settings, and if that's not as much as the roll length, it squeezes the gap size down a little [within allowance] and calculates again, until either all the roll length fits or it hits the limit on allowable reduction of the gap width.  It doesn't draw anything until it has reached one of those limits by calculation.

It remembers all your choices and offers them as defaults the next time, so you can try again with changes, without re-entering all the values.  This can sometimes allow you to get more length in than its raw result.  It could, for example, come up with this:

in which there isn't enough room around the edges for another pass, it has squeezed the gap size down as far as allowed, and the overall length is still short of a roll.  It's not built to reverse itself and re-increase the gap size.  But because of the not-enough-for-another-pass room around the edges, some more length could fit in by either calling for a bigger gap or not reducing the gap width as far as you've allowed.  You can run it again, accepting all defaults except increasing the desired and/or minimum-allowed gap width(s), and provided you don't change it enough to reduce the number of loops that fit on the panel, the length that fits will increase somewhat.

[john.uhden]

@Kent1Cooper
I am at my wife's laptop looking only at your message via e-mail, but I
really like the sound of it and the obvious thought you have put into it.
I hope I get the chance to test it out over the weekend.
Now @Sea-Haven has something he can make blink. I'd like to see him create
the illusion of water flow through the pipe. If he's any good with
hydraulics he can try to get the flow rate close to reality. (No, Alan,
Manning's equation doesn't apply to pressure flow.)
Um, would you be kind enough to draw the drill holes where you think they
will be needed, and report their quantity (in your final release)? That is
unless you prefer @ronjonp's idea of surface bars.

[john.uhden]

Please pardon my myopia.

Yes, the plywood has to be 48" square,  so the fasteners must fit within its boundary, but I don't think I said that the coil coudn't extend outside the boundary.  with a "circular" coil there is a lot of board left at the NE, SE, SW, and NW corners for drilling holes.

I just have to add feet to get it off the ground a little.

I also have to find a way to rotate the whole thing so that the outer end ends up within the one of the corners (for fastening purposes).

BTW, I stuck with using the PLINE command.  No iterations were required.  But I did use the LENGTHEN command to make it exactly 100' long.  AND before I shortened it, about 171' of pipe fit on the board constrained by only the fastener holes (I terminated the command when the coil reached the outmost hole).  So I could use one coupling but they don't come in 2' radii and would botch up the continuity a smidge.

I dunno.  I guess if 100' does any warming of the water, then I stop there.  OR I could add more length later (see all those extra fastener holes?)

I'll post the code after I add the rotation and clean it up (comments and locals and all that stuff).

[john.uhden]

@Kent1Cooper 

I'm not sure where I went wrong, but your function is still running with no results.

Maybe because I made the desired and minimum gap sizes the same?

Maybe because my test drawing is in architectural units?

Yep, it's still running..........................

[Kent1Cooper]

---

@john.uhden wrote:

.... your function is still running with no results.

Maybe because I made the desired and minimum gap sizes the same?

.....

---

That would do it.  As long as the 100' doesn't fit, it will keep reducing the gap size by 0 and trying again.

[Sea-Haven]

Googled calculate thermal temperature increase sunshine in black poly pipe.

May give some hint to rise in temperature as flow exits pipe. As I said earlier had a very small heater for my spa so would run for around 3 hours to get warm temperature, temperature of heater was high but volume of spa was large in comparison, a solar blanket may be needed to stop heat loss. 

Temperature increase from solar radiation on black pipe - Heat Transfer & Thermodynamics engineering...

[john.uhden]

Well, here it is.  I decided to go with fastener holes.

They are more labor, but I think they will keep the coil in place.

@Kent1Cooper will be pleased with my extensive use of the command or vl-cmdf function

@Sea-Haven is assigned the task of simulating water flowing through the pipe coil.

As you can see, there is more room left in the quadrants to add more pipe orbits later (just need bigger feet).

[john.uhden]

Evidently I screwed up on the mtext location.  It was supposed to be relative to the plywood, but I see that it came out relative to the coil.

At least the HATCH command written for ACAD 2002 works in 2020. <whew>

[john.uhden]

Over the weekend I dotted all the Ts and crossed all the Is and even added simulated water flow since @Sea-Haven has been too busy watching tennis (by now you should all know who Ash Barty is).

BUT I couldn't post it because some Apache renegades ambushed the forum.  Looks like it may have to wait until next week.

[john.uhden]

Finally, here is the final product.

Please try it out.  I welcome any suggested improvements/fixes.

[john.uhden]

I am annoyed by something I don't understand.

In a brand new drawing, when I run SOLARCOIL, it is supposed to set the textsize to 2.0 (1/24 of 48), but it doesn't create the MTEXT to that size.  But if I run it again, it does.

I guess one answer would be to set the 'Height property of the MTEXT after the fact, but why should I have to do that?

The fixed height of style "Standard" is 0.0.