Hi. I had to reroute the supply feed for my boiler. On the line is a shutoff, a pressure reducer valve, what looks like a pressure relief valve and another shut-off. The manual for the boiler has all these parts except there is a check valve in the place of the pressure relief valve. Should I swap out the pressure relief for the check valve like the manual has it or should I just add the check valve after the first shut off and leave the rest in the order that it was in? Thanks in advance.