I have a radiant heat system using 3/8" Onix tubing - ten 200' loops, single zone, currently fired by a Crown Bimini boiler. For the last seven years , whenever I've purged the system because of circulation problems I get a gritty substance in the water - it's mostly grey , white and tan with some magnetic particles . There's usually a couple teaspoons to a couple tablespoons per three gallons of water. So the questions are: What is this stuff? Where is it coming from? How can I stop it? Why me?
bet its Rubber. The Onix starts to break down... whatever you do NOT add gycol. That will kill the tubing. I would however flush it out , clean it w/ a good product and add a inhibitor. Rhomar has these products.