How much tubing can go in one zone?
A. A zone basically means “thermostat and pump”. One thermostat monitoring the temperature in a given area, and one properly sized pump can, in theory, supply thousands of feet of tubing. In most cases, however, zones are much smaller. The important thing to remember is that most zones consist of multiple parallel “circuits” or “loops”, and a loop should be no longer than 400 ft. (300 ft. for ½ PEX tubing). This is because after the hot water travels through 400 ft. of tubing, it has lost too much heat. An efficient radiant system should have only a 5 to 15 degree differential between the water going to the floor and the water returning to the heat source. So, you can see that if your basement zone, for example, requires 1200 ft. of tubing, you’ll want to use either (4) 300 ft. loops of tubing, or (3) 400 ft. loops of tubing.
