11-10-09, 12:15 PM | #21 | |
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I've also read Hydronic Radiant Heating. It is like sitting in a chair by a fire with an experienced hydronics installer and learning hydronics lore and rules of thumb from a seasoned pro. I found it to be interesting and enjoyable to read, but it is not a design manual. If a local library has it, you should read it. If they don't have it, you might request it. It does contain lore that you can use to double check any designs you come up with. For instance, who would think that there could be potential problems with hydronics in bathrooms? Seems like the best place to start... Well, hydronic installations, if not done mindfully, can cause the wax toilet sealing ring to melt, which causes obvious problems. (Now that I've written this, I realize that I would recommend this book, as an adjunct to a more thorough book, but it is not a systematic design manual) |
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11-17-09, 02:10 PM | #22 |
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Thermal Transmisivity Testing...
I have been considering Maxis' method of making a hydronic floor, by building it up, using layers of Sheetrock as the thermal mass material that is between rows of PEX piping. As I understand it, Maxis grouted the channel, under, around and over the PEX to insure maximum thermal conduction.
I like the idea for more than one reason...
So, I have been considering the variables, and the physical and thermal characteristics of the mass material seems to me to be a variable worthy of attention. I really like Maxis' idea of utilizing sheet rock that was left over from previous remodeling, it's a brilliant way to save money and material. In my case, however I'll be buying my material new, so the choice of material is open. I tried to find values on-line of the thermal transmissivity, or K value. I found that the K values given in various product literature, varied all over the map, and it all made my brain start to ache. So, I have been doing some initial testing of various wall-board and concrete board products. Here is a photo of my test setup... This was all just thrown together, so I could get some idea if there was enough of a difference to even worry about. I decided if there was a significant difference, I would refine my testing. So the method I followed was to use a heat lamp as the heat source, placed the same distance from my test samples in all tests. The temperatures were measured each second by three thermistors placed 1 inch apart, using my DIY Datalogger. I ran each test for exactly 10 minutes using my Eco-Experimenter's Test Box. The readings for each measurement period were averaged together. The ambient temperature was measured to be the same for all tests, my mini split does a good job of providing an even temperature. All of the test samples were stored in the same location (my living room), with 'breathing room' around each one. I kept the samples in this room for for four days, so that if there were any unusual temperature or humidity differences, they would even out. So here I have a graph of the results so far... This graph is useful only for ranking which material is a better thermal conductor than another, it is not useful for calculating how much better. The horizontal axis is the "time' axis, the vertical axis is the temperature axis, no scale is implied, however, beginning temperatures were about 70 F and ending temperatures were as high as 145 F. The time duration of the test was about ten minutes. The time shown in the graphic is about eight minutes. It is clear that in this test, Durock is the best conductor of heat then Wonderboard, and that Sheetrock (both white face and green face, anti mold) has the lowest thermal conductance of the materials tested. I'll be repeating the tests, and adding other materials that seem appropriate. Stay tuned... -AC_Hacker Last edited by AC_Hacker; 11-17-09 at 07:28 PM.. Reason: include link to Eco-Experimenter's Test Box |
11-17-09, 02:28 PM | #23 |
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I Googled "Durock thermal conductivity" and got some interesting hits.
It seems this is some good stuff for shielding your wood or pellet stove from walls and floors containing wood.. Good to know. I may re-install my wood stove someday. I was looking at a thin sheet of Durock a few weeks ago.. It was HEAVY stuff! It felt like I was handling a sheet of solid concrete. It's some impressive material, and I was wondering what it would do to my saw blades.. |
11-17-09, 03:07 PM | #24 |
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Speaking of the 3rd edition. My wife was out shopping the other day and she knew I wanted this book, so she visited the local book store. Apparently, the 3rd edition is going to be coming out ~August of 2010. I'm currently planning on holding off on doing any floor work until some time after that.
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11-22-09, 05:23 PM | #25 |
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The In Floor PDF you linked to was SUPER informative! One thing I'm still trying to figure out is pump sizing. I see the head through x feet of y pipe, but what I don't understand is what is a good flow rate. |
11-22-09, 08:39 PM | #26 | |
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I'm assuming that you're referring to this link? http://www.radiantcompany.com/manual...l_web-2009.pdf I'm still trying to work out the pump thing myself... I know that it's in my hydronic book, but I haven't dug that deep yet. So far, I know that if you pump fluid through a pipe, that there is a pumping rate where 'turbulent flow' begins. An it is desirable to pump fast enough to reach turbulent flow, because heat transfer is enhanced, and hard as it is to believe, power required is reduced. The factors affecting the threshold of turbulent flow are:
If you're gonna do some research, there is a mathematical construct called Reynolds number that is pivotal in calculating pump size. There's probably a free program that will do this for you, or a Java Script page calculator that will do the trick. Please share with us what you learn. Best Regards, -AC_Hacker Last edited by AC_Hacker; 11-22-09 at 08:42 PM.. |
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11-22-09, 08:56 PM | #27 | |
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The radiant company one is good also, but the InFloor one was more at my level. I've been reading everything *** Backwards, I thought that turbuant flow was to be avoided. Makes much more sense now. |
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11-22-09, 10:19 PM | #28 |
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dremd,
I added the 'Residential Design and Installation' to the first post of this thread. Thanks, -AC_Hacker |
11-22-09, 11:46 PM | #29 | |
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Post from Maxis (in US units)
This post, originally by Maxis, is full of useful details of a radiant floor install he is doing in Latvia (if I remember correctly). He is retrofitting a house and interestingly is using three different approaches (different approach for each floor) in his retrofit. I have relocated this post here, since it is more relevant to radiant floors than to Homemade Heat Pumps.
To make his information more accessable, I have added units that should be more familiar to American readers. I may have been a bit heavy-handed in my conversions, so they should be viewed as 'ballpark' attempts, and not as engineering data. -AC_Hacker * * * Quote:
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12-26-09, 12:44 PM | #30 | |
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Maxis, how are your warm floors working?
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How is your hydronic floor heating project working for you? Are you staying warm? I'm very interested to know how it is performing for you. I'll be starting my floor pretty soon. Warm Regards, -AC_Hacker |
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diy, heat pump, hydronic, pex, radiant |
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