Split off this thread since it's a different topic than the poster is asking about.
How much more efficient do you think it is?
Perhaps they are using the setup as a type of variable speed pump? They could run both pumps when they need full flow and they could run just one when they want to save electricity. It seems like a single variable speed pump would be a better choice.
I can see how using one 1.5 H.P pump for twice as long as a single 3 H.P pump would be more efficient, but I don't see how using two 1.5 H.P pumps for the same amount of time as a single 3 H.P pump would be more efficient. If you're generating the same flow rate, then the dynamic head should be the same.JasonLion said:JamesW, using two pumps in parallel, while prone to several problems, such as the difficulty priming, is more energy efficient than using a single pump (variable speed or not). It is similar to the principal of running a two speed pump on low for twice as long, except we get the twice as long by having two pumps. There are some ways in which the parallel I just made breaks down, mostly because dynamic head doesn't really follow the same rules with two pumps in parallel instead of one at a lower speed, but the basic idea is the same. Anyway, this is almost never done on residential pools because it adds too much complexity, but you see it on commercial pools sometimes.
How much more efficient do you think it is?
Perhaps they are using the setup as a type of variable speed pump? They could run both pumps when they need full flow and they could run just one when they want to save electricity. It seems like a single variable speed pump would be a better choice.