After a Fire Flow analysis run, I get zero available fire flow at all the fireflow nodes.
This most often occurs when either the residual pressure or zone pressure is less than the minimum pressure constraints included in the Fire Flow alternative. Both the residual pressure and zone pressure lower limit must be satisfied before the fire flow can be applied. This can occur for elements near a tank or reservoir, or on the suction side of a pump.
If the issue is occurring because of a zone pressure, one possible solution is to move junctions like this to a different zone.
In some cases, other constraints may be used as well. The automated fire flow has the option to assign pressure constraints for the whole system, as well as velocity constraints. Go to your Fire Flow alternative to confirm if you are using these.
For more troubleshooting tips, see: Understanding Automated Fire Flow Results
How does the Automated Fire Flow analysis work