Corroding pipes, part 2 – proof!


Remember when I said that you should never, ever connect copper pipes to a steel water heater because this would cause your pipes to rot out and ruin your water heater? Well, at the risk of ruining my new miniature water heater, I purposely piped it the way 99% of the plumbers and HVAC technicians do to prove a point. Yes, it’s like volunteering yourself for medical research, but sometimes you have to make a point dramatically!

Take a look at the photo of the cold water supply line to my two week old water heater. I used a nice, galvanized pipe coupler to adapt the water heater’s connection to the 3/4” copper fitting. I then slathered the fitting with “pipe dope” – a substance used to create good connections when fitting pipe.

Already, after just two weeks, there’s a spot of rust dripping down the coupler. Remember – galvanized pipe isn’t supposed to rust under normal conditions. But this isn’t a normal condition! This is a living nightmare for the steel coupler because there’s a copper pipe screwed on it. Under this condition, we are guaranteed to get galvanic corrosion.

Just to make a point, I’m going to let the pipes corrode for a week or two more before installing the proper dielectric coupling. I’ll post some more pictures after I take it apart so you can see what has happened.

In the meantime, go to your utility room and see if you have a fitting like this with a copper pipe connected to your water heater. If so, it’s probably already started corroding. If it hasn’t, you’re lucky! It might just be that the plumber put so much teflon tape on the fitting that there’s no steel to copper contact. But you really can’t count on that.

At the end of the day, it’s futile to try to argue with physics. Spend a few dollars and get the proper couplers. You’ll thank me in a couple years when you don’t have to spend hundreds of dollars replacing your water heater and your pipes!

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