I need to replace me lower heating element in my water heater. It is a screw-in type and I have the replacement part. I drained the heater but when I went to unscrew the existing element, it wouldn't budge. I've got a huge 1-1/2" wrench on the thing and with all my strength it wouldn't come loose. I only succeeded in starting to round off the corners of the elemnt. I stopped because I was afraid of doing too much damage and then never being able to replace it.

Is there a trick to unscrewing these things? It sure looks simple enough.