aarpcard
New Member
I'm trying to figure out if water main pressure booster pumps like the Davey BT series are fundamentally different in some sense compared to a well jet pump like the Grundfos JP series in the context of resilience to short-cycling.
The well jet pumps are typically designed to be controlled by a pressure switch and require a large pressure tank to ensure that the system's draw down is large enough that the pump doesn't turn on every time someone turns on a tap for a few seconds and so that when the pump does kick on the time required to refill the pressure vessel is long (a couple of minutes min) enough to allow for the pump to cool itself off from the heat induced by the high startup currents.
Whereas the booster pumps manufacturers will either recommend no pressure vessel or a tiny (2-4 gal) pressure vessel. These pumps are controlled by a pressure switch and a flow sensor which will keep the pump running regardless of pressure so long as there is some water flow.
My experience is that with booster pumps, they will not short cycle while there is flow, but due to the small (or non-existent) pressure vessels they will kick on and off every time a tap is opened or shut - sometimes causing very fast on/off cycling rates depending on how the building is using water. It appears to me that the manufacturers expect this kind of operating behavior to be normal, however this greatly inflates pump cycle count compared to the convention used with well jet pumps.
Am I missing something? Is there a fundamental difference in the design between these two pumps where the booster pump motors are more resilient to frequent short on/off cycles? Booster pumps seem to be roughly 2x the price compared to well jet pumps. Or are the manufacturers intentionally recommending inadequate installation layouts (small/no pressure vessel) to artificially drive up the cycle counts on their pumps so they wear out and will get another sale?
The well jet pumps are typically designed to be controlled by a pressure switch and require a large pressure tank to ensure that the system's draw down is large enough that the pump doesn't turn on every time someone turns on a tap for a few seconds and so that when the pump does kick on the time required to refill the pressure vessel is long (a couple of minutes min) enough to allow for the pump to cool itself off from the heat induced by the high startup currents.
Whereas the booster pumps manufacturers will either recommend no pressure vessel or a tiny (2-4 gal) pressure vessel. These pumps are controlled by a pressure switch and a flow sensor which will keep the pump running regardless of pressure so long as there is some water flow.
My experience is that with booster pumps, they will not short cycle while there is flow, but due to the small (or non-existent) pressure vessels they will kick on and off every time a tap is opened or shut - sometimes causing very fast on/off cycling rates depending on how the building is using water. It appears to me that the manufacturers expect this kind of operating behavior to be normal, however this greatly inflates pump cycle count compared to the convention used with well jet pumps.
Am I missing something? Is there a fundamental difference in the design between these two pumps where the booster pump motors are more resilient to frequent short on/off cycles? Booster pumps seem to be roughly 2x the price compared to well jet pumps. Or are the manufacturers intentionally recommending inadequate installation layouts (small/no pressure vessel) to artificially drive up the cycle counts on their pumps so they wear out and will get another sale?
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