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July 10, 2023

Tankless Water Heaters with Stainless Steel Heat Exchangers

Advantages of Stainless Steel Heat Exchangers for Tankless Water Heaters

Navien tankless water heaters use Navitech™ exclusive stainless steel heat exchangers and gas burners to deliver advanced durability and performance. 

What is a heat exchanger?

stainless steel heat exchanger for tankless water heater

All tankless water heaters have at least one heat exchanger: it’s the part of the water heater that transfers heat from the burner to the water by running water through metal coils heated by the flame. Condensing tankless water heaters have two heat exchangers. The second heat exchanger captures heat from the exhaust gas and uses it to pre-heat incoming water (improving efficiency). 

As the secondary heat exchanger pulls heat from the exhaust gas, the vapor condenses into liquid. The result is a very acidic condensate, because oxygen and carbon dioxide (and other chemicals, to a lesser extent) from the gas dissolve into the liquid.

The traditional material for tankless water heater heat exchangers is copper, which heats more quickly and costs less. But stainless steel is an exceptional material for heat exchangers in tankless water heaters because it’s much more resistant to corrosion (longer lifespan) and offers higher efficiency (important if you’re seeking a state or federal tax credit). 

How long do stainless steel heat exchangers last?

It mainly depends on the water quality of the location and the usage frequency of the tankless water heater—but in general you can expect a lifespan of 15-25 years for a stainless steel heat exchanger, with proper maintenance. Navien offers an industry-leading 15-year warranty on heat exchangers (and 5 years on other parts).

Can stainless steel heat exchangers crack?

Because stainless steel is extremely resistant to rust and corrosion, it’s far less likely to develop stress corrosion cracking compared to other metals. However any metal will experience repeated expansion and contraction from heating and cooling. Over time, this wear and tear can lead to cracks when the material is reaching the end of its service life.

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