About four weeks ago our swimming pool pump quit. I don’t know the exact date, but our pool guy, Randy, left us a note. We didn’t see the note, so a week later on his weekly visit I was home and he let me know about the pump. The motor was frozen and couldn’t be turned. A week or two before this Randy mentioned the motor was having difficulty starting. He had to pull the motor’s back cover off and free the rotor so it would start.
I knew at that point its days were numbered. I could have considered the unit had “failed” and gotten it fixed right away. But it was fall and the temperatures were dropping. I was willing to put off the inevitable.
Randy and I discussed options. I asked about variable speed or downsizing the pump. The existing 1‑1/2 horsepower unit was oversized for our modest pool capacity. He also said the pressure at the filter was a bit excessive causing the media cartridges to break occasionally. In his opinion, we could swap out the impeller and downsize to a 1 horsepower motor. Randy advised our spa jets would not be as strong – my wife and I agreed this was not going to be an issue. We discussed the variable speed option. While the potential long-term energy savings might be attractive, we decided to not invest in the upgrade at this time. We had talked about eventually upgrading the equipment and would reconsider the variable speed option at some future date.
When the repair guy came, he concurred with Randy’s evaluation. Downsize the pool pump from 1‑1/2 HP to 1 HP – done!
After the pump repair Randy came back to do the routine pool service. We observed the flow swirling into the skimmer float. Randy’s immediate evaluation agreed with mine – there was no noticeable change in the flow.
Inspection of the manufacturer’s curves indicated a reduction of flow in range of about 4% to 11% and power reduction of about 13% to 32% depending on the filter condition. Annual energy savings would be roughly 350 kW-hrs. The electricity cost savings would be around $70 annually – small potatoes. But Randy tells me oversized pool pumps are common.
Does anyone know what the reduction in power demand and energy would be if all oversized pool pumps were downsized or switched over to variable speed?