Background: my hayward super pump 1hp pump (came with house) was screaming when it ran. I bought some replacement bearings for it, but when I took the motor apart, it wasn't in great condition, there was a lot of rust and corrosion to the point that the back bearing would NOT come off. It had clearly been rebuilt before as there was teflon tape everywhere (including where it shouldn't be). Also I may have dropped the core and damaged the end of the shaft where the governor connects (oops).
Replace motor, seals, and gaskets using existing wet end.
Replace entire pump.
If I'm going to spend a bunch of money on this thing, then I thought I'd make sure that the pump is correct for my pool. I've been trying to wrap my head around all this, but I'm not sure :S
Equipment. Besides the pump, I have a Jacuzzi FM24 sand filter. It has on the side two listings for GPM. it says GPM/sqft is 15 when using a 7MAG-F (Jacuzzi 3/4pump) and 20 when using a 1MAG-f (1hp). It says it's 3.0 sqft so I guess those numbers are 45 and 60. So is my max flow rate 60? if so why the heck can't they just write that???
Plumbing is all 1.5" poly. The pool is 18x36 (extended octagon), 8ft in the deep end, about 4 in the shallow so I've been using an average of 6ft which puts me at about 29000 gal. Does that sound right?
I have 1 skimmer and a main drain. I'd estimate that the skimmer run is about 40 ft to the threeway valve and the main is about 60 (I didn't account for vertical run because I assumed it sloped). That gives me an average head of 50 ft I believe.
*IF* I'm correct, and that's a big if, then I need 61 gpm at about 50ft of head. (My plumbing caps me out at 60gpm anyway right?)
It's the average head that I'm not sure of. if it's right, then I'd need a 1.5 hp pump, but if it's closer to 40 ft, then I'm fine with the 1hp.
Can someone tell me if I'm doing this math correctly?
Is there any advantage to buying a whole new pump instead of just replacing the motor? (lets assume I'm capable of doing that).
I don't have money to burn, so I'm looking for something cost effective, but also don't want to spend money on the wrong thing.
I get the impression that a lot of the differences are just brand preference, so with that in mind, can someone check my math and make a recommendation for me?
I kinda don't trust the pool store.