Radiant heating wall

[Cadobe]

The pex pipe that I like to run for the wall would be like serpentine with both ends penetrating the floor, one end going to supply and one end going to return line. But how should I feed/supply the serpentine with hot water? From the left or from the right on the bottom? My thoughts are feeding from the left since the heat is raising up within the room. Hot water is coming from bottom running all the way up through the entire serpentine and going down to the return. Am I right?

On the other hand, for the 1/2 pex pipe. The OD is 0.625 and the bend radius supported is 8 x OD which leads to 5" radius bend and 10" space tubing.
So, my question is why this ( bend support product link ) plastic bend support from Pex Universe has a smaller bend radius? It is 3.5". Using 2 of them you will have a nice 180 turn and space tubing would be 7". Not working? Is something that I missed?

 

[Jadnashua]

The minimum bending radius for all pex the same ID is not the same; it depends on the type, -A, -B, or -C. For type -A, the minimum unsupported bend radius is 3.75", at least with Uphonor's product. The different manufacturing methods produce tubing with slightly different characteristics...type -A has the highest cross-linking, and is the most flexible. That's also why it can use expansion fittings...it has more memory along with the flexibility. A bend support helps to prevent kinking, and can relieve stress on nearby fittings. It's best to get those designed for the type of tubing, but the generic ones should work with all of them. A plastic bend support for Uphonor pex-A has a radius of 2.48" https://www.uponorpro.com/~/media/files/technical documents/specifications and submittals/nplumbing/supports/a5250500 plastic bend support.ashx?version=100820080251

So, it does matter which tubing you choose, and whether you're going to use generic pex bits, or manufacturer specific ones. I wouldn't try to use that bend support with a type -B or -C pex.

I'd feed your wall from the bottom up, or in your diagram, feed it from the left fitting. That would aid the flow through the loop, as the hotter water would tend to rise on its own, and the cooler water would fall at the end. Radiantly heated surfaces are better at providing even heat, but most people don't particularly like a hot head and cold feet.

 

[Sponsor]

 

[Cadobe]

Got that, thanks. Can you control the heat amount going through serpentine using just a simple ball valve which will limit the flow?

 

[Jadnashua]

Ball valves are not well suited for volume control other than fully on and fully off. But, it may be sufficient. IF this is going to be supplied from a manifold, getting one that has built-in flow adjustments would be better.

 

[Cadobe]

No, It is not feed from the manifold. The system that I run is reverse return. It is supplied from the main line. Do you have a link for such build-in valve please?

 

[Jadnashua]

You can use a ball valve, but the position of the valve is not linear. This often works best by using a manifold with built-in flow balancing.