Noritz EZTR50-NG 180,000 BTU Natural Gas Residential 50 Gallon Tankless Water Heater

Tankless heater does NOT provide steady hot water

First time user of a tankless heater, always had standard gas heaters in the past. Now that I have used this tankless heater for over nine months, I can say that I am not impressed . Our plumber, who installed the unit, says the problems we experience are not with the heater but rather with the constuction of our house, i.e., the builder chose not to insulate the PEX water lines ( they lay bare under blown in insulation up in the attic ); but once hot water makes it to our most distant run of about 60 ft to the kitchen/dishwasher ( timed by the plumber at 2.5 mins ), the hot water will turn cold after about 5 mins of use. Thought tankless heaters provided continuous hot water until turned off at the faucet. Plumber says unit is okay; he can not explain why the water temperature drops off. Let the water stream continue and eventually it will become hot again. A shorter run to our master bath shower ( <25 ft ) acts the same way ( especially in the cold Winter months ) the water flow at the shower gets hot and then goes cold after about 5 mins, then about a minute later it will become hot again. The standard tank heater, that we replaced with your unit, also took considerable time to get hot water to the kitchen, but the water flow stayed hot and did not fade to cold.