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Take a close look at the flow rates for each loop and how the pumps are being controlled. What kind of pumps are you using? Assuming that your're using constant speed primary pump(s) and a VFD on the secondary pump(s) it is important to stage your primary pumps based on the secondary flow. You always want the primary flow to exceed the secondary flow for primary/secondary systems. Otherwise your plant delta T will degrade and the expensive condensing boiler stops condensing. See the attached image. 
Take a close look at the flow rates for each loop and how the pumps are being controlled. What kind of pumps are you using? Assuming that your're using constant speed primary pump(s) and a VFD on the secondary pump(s) it is important to stage your primary pumps based on the secondary flow. You always want the primary flow to exceed the secondary flow for primary/secondary systems. Otherwise your plant delta T will degrade and the expensive condensing boiler stops condensing. See the attached image.
Take a close look at the flow rates for each loop and how the pumps are being controlled. What kind of pumps are you using? Assuming that your're using constant speed primary pump(s) and a VFD on the secondary pump(s) it is important to stage your primary pumps based on make sure the secondary flow. flows through each loop are being controlled properly. You always want the primary flow to exceed the secondary flow for primary/secondary systems. Otherwise your plant will develop low delta T will degrade syndrome and the expensive condensing boiler stops condensing. See the attached image. C:\fakepath\primary-secondary.JPGcondensing.