tag:blogger.com,1999:blog-8628325.post4233528426721761947..comments2024-03-15T05:59:53.929-07:00Comments on Ambivalent Engineer: Insulating the poolAmbivalent Engineerhttp://www.blogger.com/profile/16491915174390340818noreply@blogger.comBlogger26125tag:blogger.com,1999:blog-8628325.post-67444098414526835152013-04-02T11:31:55.022-07:002013-04-02T11:31:55.022-07:00Brij,
The other thing that might work in your fav...Brij,<br /><br />The other thing that might work in your favor here is the insulative value of the PEX.<br /><br />I'd be a little worried about those glass tiles, specifically because all my glass tiles have shattered. Here's a test I did that fails for the tiles that failed in my pool, and passes for other kinds of tiles:<br /><br />Put a pan on the stove, fill with water, heat to a simmer. Fill another pan with ice water.<br /><br />Place tile samples in ice pan for 1 minute, then simmering pan for 1 minute, then back to ice pan, etc.<br /><br />100% of my pool tile samples failed on the first cycle. I found others where 20% of the sample failed in the first 7 cycles. Porcelain tile samples did not fail at all in 20 cycles.<br /><br />You might want to test your tiles before you put them in the pool. I wish I had.Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-51818513019075229112013-04-01T21:51:56.824-07:002013-04-01T21:51:56.824-07:00PEX would not be in direct contact with highly-chl...PEX would not be in direct contact with highly-chlorinated water. It would be embedded in the walls and have its own water or other fluid system.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-49041418822855018092013-02-22T13:04:08.390-08:002013-02-22T13:04:08.390-08:00check out dritherm here:
http://www.dritherm.com/H...check out dritherm here:<br />http://www.dritherm.com/Html/Products.html<br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-1464937853300912872013-02-22T12:54:35.197-08:002013-02-22T12:54:35.197-08:00PEX is banned for use in pools in the US because i...PEX is banned for use in pools in the US because it can't stand hi levels of chlorine!Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-13701317769334935772012-09-01T10:25:43.844-07:002012-09-01T10:25:43.844-07:00Justice,
You'll lose nearly as much heat from...Justice,<br /><br />You'll lose nearly as much heat from the suction lines as the return lines: Your pool water will be at, what, 80 F? The water returning from a 80% efficient 400,000 BTU/hour heater at 40 gallons/minute will be at maybe 98 F. The ground is at 55 degrees F. So the suction line delta-T is 25 F and the return line delta-T is 43 F. My point is you are losing quite a bit from your suction lines too. Also, you lose heat from all these lines any time the pump is running, which should be all the time, and not just when running the heater.<br /><br />The main problem with building a box around the pipes is building any box at all. Once you've done that, putting all your lines in the box is hardly any more difficult than putting just the return lines in.<br /><br />Bottom line: box all your lines between the equipment pad and the pool. Use the rigid foam as I described, unless you figure out something better, in which case please post that here.<br /><br />I boxed a run of about 100 feet to my solar panels, along with about 200 feet of return lines around the pool. The run to the solar panels is fine, but in retrospect I wish I'd placed those return lines inside the insulated pool envelope underneath the bond beam, as I've said elsewhere.<br /><br />I put my pumps and as much plumbing as possible in an insulated below-grade vault. The filter and heater are above grade. I like the dead quiet and clean look, but clearing leaves from the filter lint basket is annoying.<br /><br />Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-89977456994779911332012-08-31T15:17:28.953-07:002012-08-31T15:17:28.953-07:00my pool equipment and gas fired heater is going to...my pool equipment and gas fired heater is going to be about 50 ft away from the pool. what can be done to insulate the return lines on that length of a run? do you feel that all of the suction and return lines need to be insulated? do you think i should build a box around all of the lines that make the run from the pool to the equipment with the rigid foam that you are talking about?Anonymoushttps://www.blogger.com/profile/00948016423733238896noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-14236857712277292612012-08-28T17:48:19.889-07:002012-08-28T17:48:19.889-07:00I don't know a lot about fiberglass pools. I&...I don't know a lot about fiberglass pools. I'm pretty sure that most spas are fiberglass shells with spray-on polyurethane foam, so you've got a good set of reference cases there.<br /><br />The main issue is the huge weight of the water, and how that weight is going to be transferred to the ground. Polyurethane foam sprayed onto the fiberglass shell can probably hold the weight no problem. Ideally, get a specification for it's compressibility, or test a sample yourself. I'm not kidding - it's not difficult at all to test and it's important to do this stuff carefully.<br /><br />You need to make sure that however you spray this foam, you get a consistent high density result. You do not want something that is springy, because the deep end will settle differently than the shallow end, and that will stress the shell. I used highload-40 which deflects 5% at 40 psi, and I loaded it to 5.5 psi with the pool full.<br /><br />I suggest you shoot some test PU foam 2 inches thick, and set a wood block into the top before it cures. Cut the foam to the outline of the block to prevent spreading strain through the block. Then put a heavy weight on the block, and measure deflection. Note that for an e.g. 3.5 x 3.5 inch block, you'd want to put something like 250 pounds on it, and measure 1 mm of deflection. That's really stiff!<br />Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-27527345209349633412012-08-28T11:26:16.623-07:002012-08-28T11:26:16.623-07:00Wanted to get your take on using the insulation on...Wanted to get your take on using the insulation on a Fiberglass pool.<br /><br />My plan would be to insulate the ground as much as possible before dropping in a preformed Fiberglass pool. I was thinking the sprayfoam would be great but wanted to hear your thoughts. <br /><br />Thanks!Williamnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-58762042438325470472012-08-03T20:26:47.414-07:002012-08-03T20:26:47.414-07:00Copper cup,
Yes, I built boxes with the 2" i...Copper cup,<br /><br />Yes, I built boxes with the 2" insulation. Those boxes are filled with the pipes, and the voids are packed with sand. I'm sure the sand is wet, and I'm not the least bit concerned about the dampness increasing heat conduction. A separate issue would be water pouring through the box.<br /><br />The boxes are made of, typically, a 9 inch wide bottom plate, two 3.5" tall by 2" thick side strips, and a 9 inch wide top plate, all surrounding a 3" diameter pipe. The top of bottom plates obviously overlap the side strips significantly. I'm not too worried about significant water flow from outside the box through the box, since the flow would have to go sideways.<br /><br />But don't mess with this idea, since the Australians have a better system: keep the plumbing inside the insulated pool envelope, by routing it just under the 1 foot x 1 foot bond beam around the perimeter of the pool. This requires less insulation, is therefore cheaper, has lower losses, and has far fewer opportunities for pipes protruding from the gunite to break.Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-67848619458084275542012-07-12T12:43:18.979-07:002012-07-12T12:43:18.979-07:00Hi Iain,
Great job on your pool build. I'm i...Hi Iain,<br /><br />Great job on your pool build. I'm in the process of building an inground pool out of ICF up in Canada. I just have a question about how you insulated your inground plumbing. I believe you just built boxes out of your existing foam panels around each pipe and then backfilled over top of the plumbing. Do you worry about water getting into the 'box' you created? I was thinking of back filling around the plumbing using pearock so water drains past it.<br /><br />Thanks for your thoughts...the_copper_cuphttps://www.blogger.com/profile/00168995581387916929noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-88703422674680911132012-05-26T01:32:16.185-07:002012-05-26T01:32:16.185-07:00Brij,
My suggestion to bring the bottom insulation...Brij,<br />My suggestion to bring the bottom insulation down to 2 inches was based on the compression amount. If the cost difference in supplying make-up heat between 2 and 3 inches of BOTTOM insulation is not large, I'd go with 2 inches, as you'll have less compression. Erring on the side of less compression seems like a good thing, but that's a gut feeling. I cannot think of a specific way 0.16 inches of compression would actually cause a failure, aside from perhaps misaligning the deck to the coping a bit.<br /><br />Email address is my first name @ my last name dot com.<br /><br />Here's how I'd think about temperature stress on the pool shell:<br /> - first, do a quick calculation for how much the pool shell expands and contracts between high and low expected temperature of the pool water. Pools survive this all the time just fine, so it gives you a sense of the reasonable strains.<br /> - second, because you have a layer of insulation completely surrounding the shell, you actually know what the stress/strain ratio is there. So you can directly calculate the compressive stress on the pool shell from heating up. My guess is it won't be large.<br /><br />Here's the last calc: where the water from the boiler enters the pool shell, you have a local hot spot at 145 F (63 C). The water on the other side of the shell can be as low as 60 F, but actually it can probably get down to 50 F (10 C) if you've had to leave the pool unheated for a while for some reason. So you've got 53 C delta-T across, say, 100 mm of concrete.<br /><br />The hotter exterior of the shell is going to expand 10 ppm/C, or 530 ppm, relative to the interior of the shell, in that region. If I assume that the shell doesn't bend as a result, we can multiple by Young's modulus for concrete (30 GPa) and see that the interior and exterior will experience something like +/- 8 MPa of stress.<br /><br />The usual compressive strength of concrete is something like 30 MPa, so you've got 4x margin there, but the tensile strength of concrete isn't nearly so good (maybe 3-5 MPa). Given these numbers I would revisit your boiling temperature numbers. When the pool is at 50 F, and you turn on those boilers, the water returning from the pool to the boilers might be significantly colder than 125 F. Check that. Also, my assumption that the concrete is the same temperature as the pool water is probably off by a bit. If the temperature delta across the concrete at the hot spot is a lot smaller, you might have enough margin on the tensile strength of the concrete. But it needs to be a lot smaller, otherwise I suspect you might get a bit of delamination in the shell near your hot spots.Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-75345233926500177392012-04-14T23:21:13.792-07:002012-04-14T23:21:13.792-07:00In my last post the temperatures were incorrect
Te...In my last post the temperatures were incorrect<br />Temp of water in PEX entering circuit (supply)about 145 F<br />Temp of water in PEX exiting circuit ( return) about 125 F<br />Max temp of concrete about 115 FAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-45406323540361692262012-04-14T19:56:14.359-07:002012-04-14T19:56:14.359-07:00Ian,
Thank you for your very helpful comments.
Co...Ian,<br />Thank you for your very helpful comments. <br />Covering concrete with thin PE film is excellent suggestion. <br />On thinking thru, I agree, putting the bubble cover under pool cover is not possible.<br />I did ROI on 2, 3 and 4 EP on floor and find that 3 inch is best. Is your suggestion to bring down to 2 based on mm compression? <br />I am not clear on how to fit the piping inside the concrete shell. If you send me an email address I can send you PDF of the pool drawings including the piping layout and the shell for your suggestion on how to fit the piping within the concrete.<br />The Delta T for PEX closed circuit water entering and exiting the boiler is 15 F so the RCC shell will never see a temp. higher than 100F though due to heat transfer, I guestimate max RCC temp will be 95F. Do you think there may still be issues of expansion joint/cracking due to thermal cycling. The initial time to get from say 60 F to 90F will be 7 days.<br />Again, thank you for your comments and I appreciate any reply that you may have.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-17186462927771827182012-04-11T16:12:00.295-07:002012-04-11T16:12:00.295-07:00Brij,
- If the local dirt isn't sucking water...Brij,<br /><br />- If the local dirt isn't sucking water out of the concrete shell, you might think about putting plastic over the concrete. This prevents drying out perhaps better than water spray, since it protects the entire thickness of concrete evenly. If you spray (which is what I did) the concrete surface is going to cycle through dry spells and not cure as well.<br />- Think about putting your pipework inside the concrete shell. In particular, the top 18" rim of your wall is probably a foot thick or so. Right below that, outboard of your structural shell but inside your insulating layer, you've got plenty of space to put your pipework. This eliminates the extra heat losses through the pipe insulation. (I lose more heat through my pipe insulation than through the pool to ground envelope!) It's also simpler -- all that pipe insulation is a hassle. Finally, you eliminate many of your PVC lines going from ground to concrete, which is a prime failure location.<br />- Your pool is fairly shallow. Ground loading should be about 2 psi, which will compress the EPS 4% or 0.16 inches. That's probably okay, but you don't need all that insulation on the bottom. Why don't you knock down the bottom EPS to 2 inches thick?<br />- I would think about temperature cycling all that concrete when you turn that diesel (EGAD!) boiler on and off. This might be your biggest risk, and I would not take it without a careful understanding of what you are getting into. Most concrete structures the size of pool shells have expansion joints, but your shell probably doesn't.<br />- I find it unlikely you will get a bubble cover UNDER the Aquamatic cover. I use a bubble cover over my Aquamatic, which I think raises the R-value to about 1.5. Thus the top cover completely dominates my heat losses now that the ground insulation is well under control. Make sure that cover stays dry (pump it off right after any rain), or you will lose a lot more heat through it. If you've got a R-1.5 cover, ambient avg 50 F, and 88 F pool, you will lose 730,000 BTU/day through that cover. Your heater will do the job, except maybe in rain and wind, which will increase your losses to at least 2,000,000 BTU/day.<br /><br />Sounds neat!Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-18269948208724261992012-04-09T18:32:51.284-07:002012-04-09T18:32:51.284-07:00I am building a in ground, outdoor pool in New Del...I am building a in ground, outdoor pool in New Delhi, India using poured in place ready mix concrete and single cage rebar. 9 inch thick concrete floor and 6 inch thick concrete on walls using standard wood shuttering forms. Pool is rectangle L=60 Ft W=20 Ft D= 4 Ft sloping to 4-1/2 Ft. Concrete shell to be cured with water spray for 21 days and then waterproofed with thin coat 0.04 inch Laticrete waterproof compound (USA make) and tiled with locally made 1 inch X 1 inch glass tiles on mesh backing fixed Laticrete epoxy grout. Pool cover is Aquamatic, in wall rail, with hydraulic motor. <br /><br />Propose to insulate under floor and behind walls with locally made EPS (3 lbs/cu ft, compressive strength 50 psi at 10% compression) 4 inch thick on floor and 3 inch EPS on walls. Compacted crushed rock and geo textile as floor base. Will insulate piping with 2 inch XPS foam 2 lbs/cu ft density, pipe sections. <br /><br />Radiant heating of pool using hot water running thru PEX tubing 0.75 inch I.D. at 12 inch centers on floor and walls tied to rebar cage. Heat source is diesel fired burner and hot water boiler make Riello ( 150,000 BTU/Hr). Water in PEX tubing circulated using Grundofos pump 1 HP. Bubble type solar blanket may be used under pool cover if heat loss excesive. Want to raise pool temperature to 88 F in 5 to 7 days initially and then maintain continuously from end Nov to early April. Coldest period Jan and Feb ambient min 40 F and avg 50 F. Pool cover will be kept closed entire heating season except 2 hours per day when pool in use. Heating not required mid April to end November and pool cover can be kept retracted during this time.<br /><br />Spa is square 8 Ft x 8 Ft and 3-1/2 ft deep, adjacent to pool on the shallow side. Similarly insulated as pool but without PEX tubing. Spa to be heated using same hot water boiler as used for pool but using a plate exchanger mounted on the bolier skid.<br /><br />Request comments especially on possible problems caused by EPS compressing and cracking concrte.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-25200957086941811572011-08-10T01:07:32.419-07:002011-08-10T01:07:32.419-07:00This blog is full of useful information on pool. T...This blog is full of useful information on pool. Thanks for the tips.Spa Enclosureshttp://www.poolandspaenclosuresusa.comnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-39918161157642349432011-07-25T17:41:16.577-07:002011-07-25T17:41:16.577-07:00Yes, polyurethane foam roofing is definitely anoth...Yes, polyurethane foam roofing is definitely another way to accomplish the same thing. Note that builders don't use that under floor slabs. I'd do a bunch of research on polyurethane interacting with the groundwater and bugs, etc, before I committed to that.Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-37456857859665607652011-06-20T03:55:50.724-07:002011-06-20T03:55:50.724-07:00Great job done. Thanks for the information. Polyur...Great job done. Thanks for the information. Polyurethane foam roofing will also be found useful in this.Polyurethane foam roofinghttp://www.oceansevenroofing.com/Services/Foam%20roofing/Foam%20roofing.htmlnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-34809404331482595972011-06-16T23:22:58.508-07:002011-06-16T23:22:58.508-07:00thanks for sharing great project with all. it is v...thanks for sharing great project with all. it is very helpful to those who want to insulate poolPool Safety Certificatehttp://www.poolinspectionsbrisbane.net.aunoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-69355091140638599022011-03-11T09:24:07.135-08:002011-03-11T09:24:07.135-08:00good way to insulate your pool i am really going t...good way to insulate your pool i am really going to work on this .. steps coolpolycarbonate sheetshttp://www.sapphiresourcings.comnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-44751998619758080272009-09-02T23:50:20.243-07:002009-09-02T23:50:20.243-07:00http://ambivalentengineer.blogspot.com/2009/08/cop...http://ambivalentengineer.blogspot.com/2009/08/coping-being-cut.htmlAmbivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-34248098239019853692009-09-01T08:04:59.906-07:002009-09-01T08:04:59.906-07:00How about an update? I would like to know how con...How about an update? I would like to know how construction went.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-57228638084017308932009-05-04T17:31:00.000-07:002009-05-04T17:31:00.000-07:00Great project. I would be interested in discussin...Great project. I would be interested in discussing with you some of your thermal analysis. Give me a call, Neil O. Anderson, 209-367-3701Neil O. Andersonhttp://www.noanderson.comnoreply@blogger.comtag:blogger.com,1999:blog-8628325.post-61634479763268191212009-04-26T23:14:00.000-07:002009-04-26T23:14:00.000-07:00We're shooting gunite on Wednesday (April 29). So...We're shooting gunite on Wednesday (April 29). So we're not yet complete. The holdup has been my fountain. See my later posts for details.Ambivalent Engineerhttps://www.blogger.com/profile/16491915174390340818noreply@blogger.comtag:blogger.com,1999:blog-8628325.post-25341110112196865392009-04-26T12:02:00.000-07:002009-04-26T12:02:00.000-07:00Any post completion notes or pictures?Any post completion notes or pictures?Anonymousnoreply@blogger.com