Start Stop for booster Pumps

[mengbly]

Hello everbody

can anyone please help me in answering the below questions

1. what is the logic behind number of start/stops for domestic water pumps, is there any formula or calculations for the same ?

2. How to calculate the expansion tank size for the booster pumps, is the tanks size also related to the number of starts and stops of the pump??

thanks

 

[PEDARRIN2]

Booster pumps can either be constant speed (older design type) or variable speed.

With a constant speed, the expansion tank is a must. With variable speed, it is a good idea to buffer the start up and shut down of the pumps.

With a variable speed pump, the on/off cycle is not as critical since it is not a full start, but I would assume 5-10 minutes between starts.

For sizing the tank, the manufacturers typically have a sizing page on their website. I use amtrol and look at the well pump expansion tank section.

 

[MikeHalloran]

To expand a little bit, electric motors don't like stop/start cycles, which reduce their life because of the extra heat resulting from the starting current. Somewhere deep in the fine print, motor manufacturers publish a limit in starts per hour above which they would prefer to not honor a warranty. Motors that are sold into price sensitive markets (like hydronics) are built with relatively little safety factor for anything, including stop/start cycles.



Mike Halloran
Pembroke Pines, FL, USA