The layout of the PEX tubing in your radiant heat system determines how much heat a given area will produce. The space between two PEX lines is referred to as the on-center distance; the closer the tubing is spaced the higher the BTU output will be
In a moderate climate, tubing for living areas tubing can be spaced about 9" apart, and tubing for a bathroom can be about 6-7" apart. In warmer climates the tubing can be farther apart and in colder climates there should be less distance between lines.
There are several high quality brands of oxygen barrier tubing available at PexSupply.com, along with everything you need for your radiant heat project.
