Measuring Gas Pressure using a Manometer

A manometer is referred to as a pressure measuring instrument, usually limited to measuring pressures near to atmospheric. The term manometer is often used to refer specifically to liquid column hydro-static instruments. Most of the more common manometers measure the pressure in inches of water column.  There are many different types of manometers for measuring gas pressure but they all measure the static load pressure and the dynamic pressure.  There are digital manometers of all kinds but the most common and easiest to use is the water column manometer.

Digital Manometer

Static pressure is uniform in all directions, so pressure measurements are independent of direction in an immovable (static) fluid (static pressure basically refers to the gas pressure within the Bosch tankless water heater when the heater is NOT in operation). Flow, however, applies additional pressure on surfaces perpendicular to the flow direction, while having little impact on surfaces parallel to the flow direction. This directional component of pressure in a moving (dynamic) fluid is called dynamic pressure (dynamic pressure is the gas pressure when the Bosch tankless water heater is in operation). 

Bosch gas tankless water heaters all have some type of inlet pressure tap or measuring port for measuring the gas pressure either for natural gas or liquid propane gas.  Please refer to the measuring gas pressure section for each individual Bosch gas tankless water heater.  The amount of gas flow and pressure to the tankless water heater is dependent upon the size, type and length of the gas line itself.  Always try to use the largest size possible and refer to the installation gas line sizing chart in the manual for the tankless water heater.