We currently have a Rheem Tri-Power High Performance 40-gallon 40k btu gas unit that was professionally installed many years ago and will eventually need to be replaced. It has performed very well in that it is has a quick recovery time after someone takes a shower. I've looked at Home Depot and Menards and am really interested in getting a better model water heater than what they sell, something comparable to what we already have. I've looked at manufacturer websites and it appears the only way to get one of their units is to go through a qualified contractor. Is that true, or is there a way I can buy one and install it myself to save a few bucks?