Verify Gas Pressure

Noritz tankless water heaters require a large supply of gas to potentially meet the max demands on the unit. However, most draws will be short durations not requiring maximum gas draws, but the supply must consider maximum conditions.

Gas pressures vary widely when it comes to Natural Gas, while Propane pressure and quality is much the same everywhere in North America and everywhere else in the world propane is available.

Natural gas systems are typically at the mercy of the technology available at the time these systems were built. Gas pressures out West will have more capability to provide multiple appliances their needed supply than ones out East whose gas infrastructure predates 1900s. Its typically to see max gas pressure available in the East Coast top out at 0.3psi systems, while further West gas pressure availability has to be regulated to under 1psi.

Generally, Noritz heaters work best under 0.5psi. And the preciseness of that gas pressure range is better analyzed using a different measurement scale “WC “inches of water column.”

1 psi = 28 “WC

Inches of water column are used to express instrument readings down to the one hundreth of a decimal. It makes sense versus the ten thousandth of a decimal.

Verify the inlet gas pressure at the bottom of the heater.

Verify the manifold pressures after the regulator inside the heater.