I see your point but do you select the recirc pump for full coil gpm? Half gpm? Also, have you experienced this actually happening? You verified the coil was properly balanced to design gpm, the outside air comes in at 25 deg F with the preheat coil maintaining 50 deg F average discharge air and...
I did have one more question. Not sure why I didn't think of it before. Why don't you need a recirc pump on the chilled water coil? It is much larger than the preheat coil on every job yet it never has a recirc pump.
That makes sense, but if you reduce the entering hot water temperature based on outside air temp then you would need more hot water flow through the coil to maintain discharge air temperature. Would you still need the recirculation pump to run during this time? Also when load does pick up and...
I came across a job in Texas where the engineer says the preheat coil for a 75%OA and 25%RA VAV AHU must have a recirculation pump installed at a large stacked parallel piped preheat coil and is to run anytime preheat is required, discharge air setpoint is 50 deg F. Usually when I see a recirc...
