My thirteen-years-old 1 1/2 HP Hayward Super Pump developed a slight seal leak and the casing is all rusted out so I decided to replace the motor. I have no clue if my pump was properly sized when the pool was built . Using gauges I took the following vacuum/pressure readings at the pump:
Using those figures I calculated a TDH of 50.62 and a GPM of approximately 52. However the pressure reading on my DE filter (with a fresh DE charge) is 15 which would put the numbers at 43.69 TDH and 60 GPM. I verified both the pump and filter pressure readings by swapping pressure gauges between the two ports. My questions are:
1) Which pressure reading would I use, the pump or the filter?
2) Would the seal leak affect the pressure reading? (I'm assuming it would but I don't know how much)
3) Would the 1hp motor be more appropriate for my installation?
4) If I went with the 1 HP motor would I have to change the impeller?