One last thing. In looking at those 2 links, they both have diagrams showing the relief valve installed at the lower end of the panel header opposite the input side and the return line simply coming out the top end & down the roof line. My instructions from the manufacturer call for the relief valve to be installed on the top header opposite the return end and it also shows that the return line should come out & go up the roof and then back across the entire length of the top header and then down the side of the panels next to the input line.
Is either install acceptable??
Is either install acceptable??