Hydrotherm's Rough in Process It took two days to complete the 'rough in' process, the plumbers basically ran, from the Bosche boiler, 25 inch pink Rehau piping, into 20 down to 16 into the chrome copper, where it comes out the wall, where it meets chrome and brass pipes going into the walls and outside, ready for the boiler. The black pipe usually used for plumbing can't be … [Read more...] about Hydrotherm Hydronic heating for our Eco-friendly, Allergy Free House (Part III)