Attributes . Heat Exchanger, 12 yr. For Resisdential and 5 yr. For Commercial and Hydronic Applications, (10 yr. If Used With The Rinnai Hydronic Furnace) All Other Parts 5 yr., Labor 1 yr.; (3 yr. If Used As A Circulating Water Heater Within A Circulationloop, When The Water Heater Is In Series With A Circulation System and All Circulating Water Flows Through The Water Heater) . Names