Commissioning Concerns: oxidizer mode issues resolved

During commissioning of a thermal oxidizer that used a bypass fan to maintain source static pressure during offline operation, some minor issues arose. When switching between bypass and online modes one, or both, proof of flow switches (for the main draft fan and combustion blower) would momentarily drop out. This resulted in the burner shutting off, which would shut down the oxidizer. Another issue was the dramatic fluctuation in static pressure that occurred during mode switching. The client was very concerned the momentary drop in static pressure could adversly affect their production. Both issues needed immediate resolution.

To correct the pressure switch problem RHZ Environmental needed to modify the controls to accomodate the pressure rippling that naturally occurs during a mode change. To eliminate the pressure drop issue RHZ Environmental needed to adjust the valve and fan sequencing.

After adding two relays and a bit of code both issues were resolved. The burner is working properly and the unit is now maintaining source static pressure during mode changes. 

The next step is to apply these corrections to the two identical systems adjacent to this one.