Pex question.

[R. Snyder]

Hi everyone,
I am getting ready to plumb the Garn and have a question about the pex lines. I have 1" Thermopex entering thru the floor, outer casing is cut back to within 6" of the floor with about 3ft of the pex above. My question is how tight of a radius can you make when connecting the pex to my pipe fittings? I am trying to keep the pump as low as possible near the floor. Any input would be welcome.
Thanks

 

[bmblank]

I'm not sure what the number is, but you can give it a bend and if you end up kinking it, you should be able take a heat gun or torch and gently heat the kink until it returns to original shape. There's a sweet spot between warm enough to fix it and hot enough to burn it. At least I'm pretty sure that can be done. Might want to try some scrap if you have any around.

 

[arbutus]

The specific pex manufacturer will have a minimum bend radius. If you are trying to get it right tight, purchase a pair of the 90 degree tubing bend supports. A couple dollars each will get it pretty much as tight of a bend as you can get, keep it that way, and save you the headache of dealing with a kinked tube.

 

[Bob Rohr]

The specific pex manufacturer will have a minimum bend radius. If you are trying to get it right tight, purchase a pair of the 90 degree tubing bend supports. A couple dollars each will get it pretty much as tight of a bend as you can get, keep it that way, and save you the headache of dealing with a kinked tube.

One rule of thumb is 6 times the tube diameter. But I agree, check with the manufacturer

You can find metal bend supports or slide a long sweep PVC bend over it to help keep the bend from pulling on the fitting

Another option is transition to copper and a copper ell, less id restriction compared to pex insert fittings.

 

[R. Snyder]

Thanks for the replies. I did look up the specs from the manufacturer, they say 8 times the outside dia. I will look for the bend supports. Take care all.

R

 

[jebatty]

Not your question and I'm sure you have considered this when using 1" Thermopex, which I think has inside diameter of about 7/8". Capacity of 1" inside diameter is normally 8gpm, or 80,000 btuh at delta-T = 20F. Thermopex would be less btuh. Be sure to size your circulator properly to handle the pump head in your system.

 

[brant2000]

I've found the tubing bend supports to be somewhat too flimsy to securely hold the tubing, and it will never make a nice tight 90 deg turn. Why not just use pex elbows?

 

[Bob Rohr]

here is a good quick table for determining acceptable flow rates. Check the id of the tube you are planning on installing. Some, but not all PAP tube has a larger id.

Also pex insert fittings do add pressure drop, one or two not a big deal. If you end up with several on S&R on both ends of the run, add those to the tubing length for your pressure drop calculation.

 

[R. Snyder]

Thanks Bob,
There will just be a single pex fitting at each end, then transitions to blk. pipe at boiler and copper at the HX's. I have been working with "heaterman" for purchase and advice, so I believe I am getting the correct info on sizing the components. Have a good weekend.
R