Spiral or Back and Forth?

[Burl]

I'm ready to install my 1/2" pex tubing, and have a question about the configuration. It will be in a concrete 6" slab, 884 sq.ft., I'm thinking 4 loops, all under 260 ft. either way you do it, around 1 ft/ c-c. I realize in the spiral, if you "lose" a loop you're still partially covered. But I see a lot of back and forth stuff, which seems easier to put down. Any thoughts?

 

[PAToyota]

My understanding is that with the spiral (in to the center and back out) will give you a more even heat distribution. Back and forth will be warmer at the supply end and cooler at the return end.

I laid mine out in two spirals - one for each half of the shop.

 

[5wndwcpe]

Plus (with the exception of the turnaround) when laying out the tubing in a spiral configuration, you're only making 90 degree bends, not 180 degree bends, as with the back and forth method. This makes a tremendous difference when trying to keep the loops equally distant.

 

[z28toz06]

spiral layout?

 

[hansen1]

That was going to be my question. I understand the back and forth, I am assuming the spiral means to start on the outside walls and work inward.

 

[5wndwcpe]

That was going to be my question. I understand the back and forth, I am assuming the spiral means to start on the outside walls and work inward.

Yes and when you get to the half way point, you turn around and head back to the manifold.
One of the advantages in doing this is you always have a supply loop running next to a return loop. This will (theoretically) even out the heating of the slab.

 

[z28toz06]

I have a 24X32 building and I have 3 loops of about 230-250 feet each loop. I started the hot side of the loops on the outside of the slab and worked in. the center loop didn't matter much as it is away from the walls.

 

[wayne]

I did the same thing....24 x 28, three zones, divided into three on the 28ft length, hot lines on the outside working to the centre on each end zone. Middle zone "spiral" layout" with the hot line hitting the outside walls. If this is of any interest I could do another drawing and attach it (concrete contractor took my original) I intend to build a heating unit using a small hot water tank with a souped up element.

 

[z28toz06]

I did the same thing....24 x 28, three zones, divided into three on the 28ft length, hot lines on the outside working to the centre on each end zone. Middle zone "spiral" layout" with the hot line hitting the outside walls. If this is of any interest I could do another drawing and attach it (concrete contractor took my original) I intend to build a heating unit using a small hot water tank with a souped up element.

gas or electric?

 

[wayne]

Electric, I like the idea of no flame in the shop!