I bought a couple of dielectric unions to connect some glavanized pipe to copper in my heating system. Are these also good for connecting black pipe to copper? This got me thinking that when I installed my water heater I should have used one to connect the heat trap (I think that's what the part is called) to the copper pipe? I just used a threaded female copper connection, but I guess that puts two dissimilar metals in touch with each other.
Ian