Radiant Flooring install questions

[bowtarist]

Hi all, lurked off and on for a while. I hope I'm at the right place to get some questions answered. I built my home last year, its a barndominium. I live in N Alabama and had never even heard of a radiant floor until a friend at work told me about them while I was getting ready for concrete. I went ahead and installed the pex into the pad. I am now ready to finish hooking this system up and I have a good idea on what I need to do to finish but I would like some advice.

This is a closed loop system with one zone. I plan on using a Takagi WH. The manifolds I have now are the ones that came with the kit I bought from houseneeds.com. Its a housepex 8 port manifold. It came with 2 temp gauges, fill valves and an air eliminator.

My questions are:
Can I use pex to connect everything from the heater to the manifold or does it have to be copper?
What all components do I need to finish this? I have a list made and I want to make sure I'm not missing anything.

Thanks for any help.

 

[Plumber69]

You got a pump or is there one built in. You got expansion tank?

 

[Sponsor]

 

[Jadnashua]

What size pex, and how long is the loop? Ideally, no loop in 1/2" is longer than 200' or so, otherwise, by the time the water gets to the end, it's cooled off too much, and that area will be cold. You can't just pump it faster to get more heat into it, otherwise, it just doesn't work well and costs lots more in pumping.

A major contributor to the effectiveness of radiant heating is to adjust the spacing and the water temperature to deliver the needed heat without being excessively hot in one area. It's a bit more than a WAG on how to get it right. Is the slab insulated from the bottom and is there any moisture barrier there? If the soil under the slab is wet, it can mess with the efficiency of the system radically, as can the absence of any insulation...it's essentially impossible to heat the earth underneath...you need that to be dry to be effective, with some insulation for it all to work well.

 

[bowtarist]

I did put down a moisture barrier and insulation. I also insulated the outside edges of the slab. My loops are 200' 1/2" pex.

I do not have a pump or ex. Tank.