Takagi water heaters carry the build date inside the serial number. We know one serial format for this brand; the decoder tries each one and shows every reading that fits.
The first two digits are the year and the next two are the week of that year. An S in front is a factory code and is ignored.
1514E000453 reads as week 14 of 2015.
One source Building Intelligence Center, InterNACHI inspector forum
A gas tankless water heater usually lasts 15 to 20 years, and sometimes longer, because there is no tank to rust through. Scale buildup in the heat exchanger is what shortens its life.
How long does a tankless water heater last? · Should I replace my water heater? · DC Dept. of Energy & Environment, U.S. DOE Building America
A.O. Smith · American Water Heater · U.S. Craftmaster · Bradford White · State · Reliance · Kenmore · Whirlpool · Rheem · Ruud · Richmond · GE · Marathon · Rinnai · Navien · Noritz · Bosch (tankless water heater) · Lochinvar · GSW / John Wood · Paloma · HTP / Westinghouse / American Standard (water heaters) · Giant · EcoSmart / Eemax · Stiebel Eltron
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The age you just looked up is the kind of fact that gets lost. A written record of serial numbers, install dates, repairs and who did the work saves the next owner, inspector or insurer from guessing.
A lifetime logbook for the house, organized by system, with room for serial numbers, install dates, repairs and contractors. It stays with the house for the next owner.
Galvanized, polybutylene, cast iron and the sewer line: what fails, what it costs, what insurance won't cover and how to decide.
A buyer's guide to older homes: wiring, pipes, lead, asbestos, insurance refusals and what the repairs actually cost.
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