I need to pull and replace the elements in my water heater. The problem is, I can't get the old ones out. My Channellock pliers can get a grip, but slips off pretty easily. Is there something better for removing these?
Using channellocks/pliers can fail because as you apply torque, the grip expands, causing it to slip. Adjustable wrenches do not have this problem, but still might fail due to torque being applied only to two points on the bolt head. You should be using a socket, which applies the torque evenly to all six sides of the bolt head. Hardware stores sell "cheap" thin-walled sockets made for water heater elements, which will likely work well for you.
Do a Google image search for "water heater element wrench" to get an idea for what these look like. I can't find a free image of one to insert here....
Another option would be to use a high quality socket and a long "breaker-bar", but this would be more expensive. The socket size is generally 1 1/2 inches.
If you continue to have trouble, try adding a little bit of penetrating oil (and then waiting maybe half an hour), or heat that area of the water heater with a torch in order to use thermal expansion to your advantage.
The cheap stuff doesn't work, so don't waste your time and money to buy them. Get a breaker bar with a good deep well socket and let her rip. Be sure to kill the juice first!