advice

MPJ347

Happy new year to all,
I'm doing a snow melt at my house and I need some advice. I'm pouring the garage slab first and redoeing the drive come the spring I hope. I want to leave a sleave under the garage slab so I can snake the tubing back to the manifold in the garage after. I need 16 supply and return tubes for the snow melt. I'm wondering what would be the best method for this. I was thinking 2 10" sdr pipes. Any advice would be great, thanks.

MPJ347

Sorry, their 5/8" tubing

SWEI

Have you considered piping it as a reverse return with long "embedded manifolds"?

Zman

I would put the manifold in an underground landscape box at the edge of the driveway in a central location. This would give you more even distribution of heat and less resistance overall.
The main supply size size would depend on the design requirements of the snowmelt and the distance. To give you a rough idea, if you needed 15.5 gpm, 1.5" pex would work well.

Gordy

Agree with @SWEI . Then you have less piping to go back to the garage. Better than trying to snake 8 supply, and 8 return tubes. Or is it 16 of each?

Also you could stub the piping out side the garage floor in the subgrade, and avoid dealing with getting back to the garage come drive way time.

Zman

Gordy said:

Agree with @SWEI . Then you have less piping to go back to the garage. Better than trying to snake 8 supply, and 8 return tubes. Or is it 16 of each?

Also you could stub the piping out side the garage floor in the subgrade, and avoid dealing with getting back to the garage come drive way time.

I was assuming 16 each.
Personally, I like the manifold outside the slab for easier service.
Either option is better than running all the tubes back through the garage.

MPJ347

I have not thought about a reverse return. I think I'd rather have a manifold on the garage wall instead of a box next to the driveway. It's 16 loops of each. Thanks

SWEI

A properly sized system with (nearly) equal loop lengths will pretty much self-balance. For odd loop lengths I would want balancing valves someplace, but I have enough faith in PEX-a with F1960 EP fittings to be comfortable burying them for life in a pour or a sandbed. You do need a fair bit of line pressure or pump power to fully purge something with those kind of design flow rates.

Gordy

Yes pay close attention to loop lengths being +/- 10% of each other, and reverse return makes balancing a none issue to deal with.

They make hand hold boxes if you want a manifold outside in the grade.

For right now hard pipe the snowmelt to an outside handhold box. A remote manifold station will cut down considerably on loop lengths. Your adding 40 additional feet depending on location in garage to each loop. Figuring min. 20' deep garage.

MPJ347

I was looking at a drawing of a reverse return. How would I purge or isolate each loop if necessary? Gordy, the loop lenths should all be the same as per design. I was thinking of putting the manifold inside the garage next to the garage door. The supply piping would need to run about 11' along the wall. I would really like to have access to the manifold for service purposes. There is really no incospecious place to install a box outside. So do you gentlemen think a 10" pipe would be good as a sleave or run 32 smaller sleaves? Thanks.

Gordy

A 10"I'd pipe is 78 sq in. 32 5/8 pex tubes takes up 31 sq in. Figuring area of each individual pipe. But the pex is going to have gaps when stacked in the pipe even when touching.

347

Thanks Gordy,
I'll use two small pipes.