I had a new full-size electric water heater installed in a condo about 3 years ago. My current tenant complains that it only produces hot water for 10-12 minutes, then it becomes icy cold. She says this is unacceptable. Is 10-12 minutes unacceptable or is it normal on an electric water heater? It seems I had this problem with the last water heater and immediately after this one was installed. If I need to buy another one, is there a recommended brand? I paid $1000 for this one including installation and securing it according to safety specs which I heard was a rip-off. Please advise me. Thank you.