Hey you guys....
Thoughts? Tips?
Brettski:
Did exactly this for a 30x40 pole shed workshop for my best buddies ol' man. WORKS GREAT! Used 4 runs of about 300' each, 1/2" ID Pex, spaced at 12" OC...about 1 foot of tube per square foot. 300' per run is about max, otherwise you can't use the cheap (readily available) TACO brand, $100 pumps...not enough head to overcome flow resistance. Much longer and you have to step up to 3/4" tube and "High Flow" pumps.
We started 6" from ext. walls, and alternated flow (first run CW, second CCW, etc.) but you can do that with how you hook up PEX to manifolds. Just start wherever and make loops leaving enough tube to reach back to the start point. For us, it's all one "zone".
Not sure why folks want the manifold in a box on the floor...I mounted manifolds on the wall and ran tubing up to it, but it's a shop so we didn't care about "hiding" all that stuff.
Make sure your insulation is rated for below grade work, and High Density...AND make sure you insulate the heck out of the edge of the slab. We messed up a bit...snow melts away from the slab outside, so we know we're losing heat, but it still only takes $50-75/month to keep the place at 70F+.
We also used these plastic clips (google PEX screw clips) that twist into the insulation to attach the tubing. Laid out rebar on top of that...never have to worry about puncturing that tubing later as it's in the bottom inch or so of 5" of concrete.
All was bought locally at Menards...maybe a grand for everything, including the 50 gal gas HWH. I'm doing this in my shop this summer, too.
