There are several methods of attaching the tubing to the sub-floor. Thirty years ago we installed our first radiant system by simply driving nails on the side of the floor joists and hanging the tubing on them. Over the years we have used several methods, we have installed over 2,000 systems and have used every thing available including Gyp-Crete, tubing half clamps, hand staplers, air staplers, metal pans, plastic pans and grooved sub-flooring. Here is a list of the different systems and the advantages and disadvantages.
Lightweight concrete, although we have installed a few systems of this type, we have seen some of them fail.
The air stapler requires a compressor and is hard to get into tight places, also the staples can damage the tubing.
The metal pans are suppose to spread the heat out more evenly, all the testing we have done proves this to be untrue, also many people complain of noise.
The grooved sub-floor is very expensive, causes streaking and can cause extensive damage to the sub-floor in case of a leak.
The tube talons or half clamps have proven to be a good choice, they are inexpensive, and you only need a hammer to install them.
The Peter Mangone, RB-5 hand operated staple gun has proven to be the favorite choice of the installers, and is specifically designed for heating applications of PEX.