pump speed

Dave_22

Did you re-pipe primary/secondary since you had condensing issues? Also- the faster speed will cause a lower DT and return hotter water to the boiler. This may be good in your case if your return water was too cool before causing condensing issues.

Timco

variable speed Grundfus pumps

Sooo...last year I posted a question about pump speed...3 Grundfus 15-42-F. One feeds 2" and 4 large rads, one feeds 2" and 2 med rads & kick heater, and 3rd feeds 1" and 2 med rads. I had condensing issues with my old Laars boiler, and since replaced the boiler and increased my manifold sizes. Do the 3 pumps need to be on #3(fastest) or can they be on med or low setting? What is the correct way to calculate this? I was told low is fine, but want to maintain good flow.

Thanks,

T

Al Letellier_13

pump speed

you need to calculate system head and GPM's required like you would any other system and use the pump curve supplied by the manufacturer to set the correct speed.

Timco

Yes...re-piped all near boiler piping due to condensing issues...as well as an entire run that was run in 1/2"!!! No pipe less than 1" near boiler now, and have never heard the boiler pop or crackel since, and return temps are much higher. Just do not know if I need them on high.

T