I am currently considering the installation of an indoor wood boiler in an outbuilding. The run from the building is about 100 feet. I have been looking at the various manufactured insulated piping systems that come in a piece of 4 inch plastic corrugated pipe. I'm not really sold on these as they seem pricey.
I also looked at the system on these pages were liquid foam was placed around the pipes buried in the trench. Again, the liquid foam seems pricey.
As an alternative I am considering constructing a U shaped trench with 4inch foam board insulation. The trench would be 6 inches wide and 6 inches tall. I would then pour about 3 inches of cement in the bottom of the trench, lay my pex on top of the cement, then cover the pipe with cement. Finally I would put on top layer of insulation to give a complete box of insulation. This will address any issues with water, insulate the pipe, and be relatively inexpensive. Any thoughts or concerns on this approach?
I also looked at the system on these pages were liquid foam was placed around the pipes buried in the trench. Again, the liquid foam seems pricey.
As an alternative I am considering constructing a U shaped trench with 4inch foam board insulation. The trench would be 6 inches wide and 6 inches tall. I would then pour about 3 inches of cement in the bottom of the trench, lay my pex on top of the cement, then cover the pipe with cement. Finally I would put on top layer of insulation to give a complete box of insulation. This will address any issues with water, insulate the pipe, and be relatively inexpensive. Any thoughts or concerns on this approach?