Oh_var MTR is spot on. My buddy has a CB within 75' of his house with thrmopex and he is losing @ 5 degrees. I on the other hand didn't take my own advice. I'm heating a big house and outbuilding and am 125' away from both. I've got @ 250' of homemade insulated pipe in the ground at 3' deep and I'm afraid to see how much my temp is dropping. Oh well at least i love cutting wood