Replies

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   Guest_ | Nov 06, 1999 01:37am | #1

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   don't know about the sand but there are other acceptable methods of using hose above a subfloor below a finished floor. i have hose in concrete in 1st floor and hose,sleepers,ply and then ceramic in the baths on 2nd floor. laying hose in tighter loops under this one makes for no cold/warm spots. the only diff i feel is that a more constant flow of water is necessary because of the lack of mass. hopefully the hydronic wizard will see your message and respond. best of luck to ya

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   Guest_ | Nov 06, 1999 04:40am | #2

   *There was a post here a few weeks ago about an article in the Journal of Light Construction that mentioned using sand in lieu of gypcrete. The article is at:http://www.jlconline.com/jlc/archive/energy/radiant_sept99/page3.html#OptionsforWarmWoodFloors

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   Guest_ | Nov 06, 1999 06:38am | #4

   *Alayeska Chuck,You are in for a treat. And just a little work.Take six parts of the finest masons sand available and mix it with 1 part of the absolute cheapest portland cement you can buy. Add 1/3 part lime.First you start with dampened sand(not wet). Go get a $150.00 mini garden tiller(Mantis won't work--tines are straight, you want curved tines).It's winter there right? Have your sand dumped anywhere that it won't freeze(you could use a finished garage floor) and leveled to a depth of 4-8 inches. If the sand isn't damp yet, this is the time to dampen it.Calculate the depth of sand and convert it into cubic footage. You want the six to one ratio to be based on volume, not weight. In other words, if you have six 5 gallon buckets of sand, you will want to add one 5 gallon bucket of Portland Cement (you could also use cementa from mexico[g]. Remember that 1 bag of Portland is usually 1 cubic foot.Next, evenly spread the calculated amount of Portland over top of the damp sand. Also spread your hydrated lime evenly over the cementa. The ratio of lime is based on the amount of cement, so you see, 1 bucket of cement deserves 1/3rd bucket of lime. Start up your mini-tiller and Roto-Hoe away. Remember that you may have to add more water after you have blended this concoction to the following consistency:>>Take a handful of the sand/cement/lime mixture and compress it with your hands. Once you have a nice compacted ball, toss it from one hand to the next. Not to the ceiling, dude, just 6-8 inches. What you are checking for is cohesiveness of the ingredients. If you can toss it 2-3 times without it breaking up, you are fine. If when you squash it into a ball and water drips out, it's too wet. Toss on more sand and the proper ratio of cement and lime and remix to the proper consistency.>>>Hopefully, you have made the following preparations prior to mixing your "drypack":1) Cover subfloor with 4-6 mil visqueen. Install your 2x2 sleepers. If your sleepers are already installed, no problem, you can check with a local chemical company for a chemical by the name of Methyl Siliconate(water glass). It's cheap and you can spray the sleepers and the subfloor using a Hudson srayer to prevent the moisture from the "drypack" from passing to the wood. Oversimplification, there are also other materials you can use and other reasons to seal any wood that comes in contact with the damp mixture.2) You will want to have on hand something to compact the drypack(10" x 10" asphalt tamper is perfect) as well as screed it even with the sleepers.3) Wheelbarrow or haul the drypack into the space with buckets.4) Dump the drypack into the area you want to fill. Fill it proud of the top of the sleepers by at least 1 inch. Just use a straightedge to move it around.5) Tamp the living shit out of the drypack to thoroughly compact it. You are looking for "density and compaction" around the tube. Beat that puppy to your hearts' desire, your tube will be okie-dokie fogeddaboutit.6) Screed the excess mortar off with even with the sleepers.7) Use a flat trowel to consolidate the surface.8) Cover with damp burlap or lightly spray with water from the Hudson sprayer for the next 3 days to slow the release of moisture resulting in a stronger cure and reducing cure shrinkage.You could use stone dust instead of the sand/cement/lime mixture. The advantage of "drypack" over stone dust is the fines of the cement and the lime fill the voids between he sand particles. The more tube surface in direct contact with the tubing wall, the greater the co-efficient of conductivity. Greater conductivity coupled with a homogeneous mixture lacking voids results in a faster and further flow of heat in the lateral plane.[grin]Beware, the mixture and compaction method is the very same as a Tile mud bed. However, there is a big difference between the method above which is not intended as a bondable substrate and preparing a substrate for receiving tile or stone.Any other questions. Just ask.btw: Big Job: TroyBilt rototiller, available at your local Taylor or U-Haul Rental Center. Just don't tell them what you are tilling, and don't mention my name. [I will deny it]Happy Heating,Jeffps: You should hook up with my bud Ron Matviak over in Eagle River when it comes to planning your boiler room. email me if you need an intro.

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   chuck_t | Nov 06, 1999 06:38am | #3

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   Can anyone make recommendations about whether sand or stone dust will act as an acceptable heat sink for a radient floor heat system? Concrete is very expensive here and the nearest gypcrete contractor is 130 miles away. The tubing/sand would be installed between 2x2 sleepers 16" oc which would be perpendicular over 12" TJI's @ 16" oc with 1 1/8" t&g plywood. The floor is over a heated basement and would have wood flooring laid over the 2x2 sleepers. Thanks.