“One of frequently asked questions we get is “can PEX be buried”? Yes, our PEX can be buried. The PEX tubing insulation that we sell is meant to be underground, as it is the protective outer tubing that surrounds the insulated PEX pipe.
Also, from talking with people about installing wood furnaces we know that many are curious if 2 inch PEX pipe is better than 1 inch. From our experience, 2 inch pipe allows too much water to run through and the best diameter is 1 inch PEX pipe. Remember, you can buy PEX tubing that is either insulated or raw. Make sure you are getting insulated pipe when using for outdoor wood furnace installation.”