A.O. Smith 120 trough 500 - Manual (Page 12)

BTR TANK TYPE HEATERS
SERVICE HANDBOOK
A.O. Smith Water Products Service Handbook
Irving, Texas ©2000 Training Department
11
GAS PRESSURE REQUIREMENTS
Natural Gas Propane Gas
Maximum Supply Pressure 13.8" w.c. 13.8" w.c.
Minimum Supply Pressure 4.5" w.c. 11" w.c.
Manifold Pressure 3.5 " w.c. 10" w.c.
The supply gas pressure is normally measured at the dirt leg or at the gas pressure
tapping on the gas supply shutoff valve. This reading must be measured with 'flowing'
gas.
The manifold gas pressure is measured at the manifold pressure tap of the gas valve
when the gas is flowing.
Supply Gas
Dirt Leg
Manifold
Gas Port
Manifold
Pressure
Tap