HOW IT WORKS

CSST is a flexible, stainless steel pipe wrapped in PVC. It is most often installed in a central manifold configuration with home run lines that extend to gas appliances. Flexible gas piping is lightweight, bends easily, and can be easily routed around obstacles. It also requires fewer connections than traditional gas piping. The multiport manifold allows for expansion of the system to accommodate room additions or new appliances.

Read a PATH Field Evaluation:

Model reMODEL, Philadelphia, PA

INSTALLATION TIPS

"You have to pay attention when you install flex pipe because the pipe has a memory when you uncoil it," Wagner says. "If you get a loop in it, you can't just untwist it to get it straight. It's not like an electrical wire where if there's a little twist in it, you can still make it look good."

"CSST is flexible, but it is also sort of thin, so it can kink. You're not supposed to make a sharp 90-degree turn with it. If you do need to make a 90-degree turn, use a fitting."

"You have to treat it somewhat like water pipe. You have to protect it wherever it goes through studs and where nails can get to it. But the manufacturer gives you all kinds of stud protective plates."

"You also have to make all the other tradesmen aware of the flex pipe because it is more vulnerable than steel," says builder Dave Pusey. "It is possible to put a leak in the CSST pipe with a drywall screw or shoot a nail through it if it's not protected properly, which you don't have to worry about with conventional cast iron pipe."

WHEN TO USE FLEX PIPE

TECHNOLOGY HIGHLIGHTS

This project included the following PATH-profiled technologies:

• CSST flex pipe

"If you only have straight runs in the basement, it probably wouldn't be economical, but flex pipe is a real time saver if you're also roughing gas pipe into the second and higher floors," Wagner says. "If you had to get gas piping up to the third floor of an apartment for a washer and dryer, for example, the time savings would be huge. Once you start going up a wall, across a floor, up another wall, and across another floor, with black pipe you would have all those joints that you're trying to fish hook a pipe through. That's where you're saving your time with CSST."