Had some work done on hot water system using black iron piping. Transition made to copper with dielectric unions. I see a problem in that a brass valve was placed on the black iron line (basically BI nipple brass valve, short BI nipple, then dielectric union) with the valve piggy backed between 2 Black iron nipples. I asked if the valve should be on the copper side of the union and was told that brass does not react to black iron nearly as bad as copper. I should have no long term problems. Is this the right way or should I have the valve place on the copper side?
the black iron will decay in no time. get ridd of it and replace the water distrubution with copper. then you will have peace of mind when you go away for vacation. you wont come back to a flooded house.