calculate the heat loss in BTUH, based on system temperature, ambient conditions, and insulation characteristics. 3/4-inch copper pipe is generally provided with 1-inch thick fiberglass insulation. Depends of course on application. Then, calculate heat loss to determine appropriate...
test the resistance through the element.
The procedure is in the manufacturers service guides, but should be simple for an electrical engineer, electrician, or plumber with a voltohmeter.
He has installed the wrong type of check valve or the valve is in the wrong position. A swing check should only be in the horizontal position. You are getting water hammer upon pump shut-off. The solution is a weighted check valve designed to shut tight instantaneously at pump shut-off.