Hey Eric, and fellow boiler folk, I am getting ready (this spring) to run underground pipe from my boiler (royall boiler in garage) to my house. I spoke to a guy ( Boiler manufacturer) about this and he recommended to run insulated copper pipe underground. He stated that if the power goes out and the blower is not on that the unit can buildup to much pressure, back flow, and can blow out the pex tubing (he said that the pipe balloons out). Can I prevent this by using and automatic zone valve? I want to use this so that it can gravity feed the water during a power outage. Is pex that touchy? The guy (rick) said copper pipe can take the pressure more. Do you have any suggestions on where to buy insulated copper pipe? I thought about making my own (copper tubing, foam insulation, in pvc pipe) I just want to do this right. I want a pressurized boiler because they last.