My home wareanty company refused to fix a pipe leak because of what they call an illegal connection of iron and copper pipe from my water heater. Should they be allowed to deny service based on this presumed cause of the leak? The leak is on a pipe that's 3 feet away from the so-called illegal connection. Both leaks are at a corner connection.

Can copper be connected to iron? Is it illegal for copper to be connected to iron?

I suspect it is the actual fittings used are not to bs standard

You can connect copper piping to galvanized iron piping, but you need to use special connectors (dielectric unions) that isolate the two metals. If you allow the copper to contact the galvanized iron piping directly, a galvanic reaction occurs, and causes the iron piping to corrode. Eventually a leak will develop at this spot of corrosion. The question is do you have this special connector. I'd wait for some more responses here, there are some great plumbers here to help. Can you take a picture of the connection and post it so they can see it?