We had Lowes install a Whirlpool model Nu40T121-403 natural gas water heater early October 2012. The temp controller went out in October of 2014. I replaced the controller myself at a cost of $30 for overnight UPS from the manufacturer, American Water Heater. The controller went out again almost exactly one year later and I again replaced it for the $30 shipping charge.in both instances the customer service person told me the malfunction was probably due to my not flushing the heater annually, causing a sediment buildup. The water to the heater not only flushed annually, but is filtered through a water softener and there was absolutely no evidence of sediment in the drain water or on the part of the control that is in the tank. Now it has stopped working a third time. I called Lowes about replacing it, but they only carry Whirlpool, so won't be buying a replacement from them.