Pool Pump calculations.....help?

[1PoolNoob]

Ok, so my pool pump is dying and needs to be replaced. The problem is that it is extremely old, about 30 years, and pumps were not nearly as efficient at moving water as they are now. I am trying to decide if I just put in a new pump with the same hp if it will be ok, and not too much GPM for my system (sand filter, piping, etc.).

Can someone help determine approx how much Total head pressure resistance is in my system (without expensive tools)?

Old pump: Pac-Fab Hydropump (Model: WE 700) 3/4hp
System Piping: 1.5" I believe
Pool size: 30,000 L or 7800 gal
Piping distance from skimmer to to pump: 45 ft horizontal, 7 ft vertical
Pool has 1-skimmer and 2-return lines
Pump runs all the time during summer.

Sand filter specs 17-in I think (it is old also):


Specs for the motor of old pump:



I am looking at putting in a Hayward Superpump 3/4hp and am concerned it will be too powerful for my system to handle.

THANKS!!!!!

[PoolDoc]

Install the SuperPump, but with a ball valve between the pump discharge and the filter, so you can throttle the flow. For a 17" filter, the flow rate for EFFECTIVE filtration will not exceed 20 gpm.

Plan to replace the filter next year, with a 24" TR60 or equivalent.

[1PoolNoob]

Install the SuperPump, but with a ball valve between the pump discharge and the filter, so you can throttle the flow. For a 17" filter, the flow rate for EFFECTIVE filtration will not exceed 20 gpm.

Plan to replace the filter next year, with a 24" TR60 or equivalent.

Thanks for the reply.
If there is a ball valve restricting flow between the pump and filter, won't a lot of pressure build up at the pump and cause it to work harder and burn out faster?

How would you know how much flow to restrict eight he ball valve?

For the filter, do you mean that it filters at a max flow of 20 GMP, so anything above this will put unneeded pressure on the filter, even if there was 50 GPM from the pump it would still only go through the filter at 20 GPM? Doesn't the Hayward superpump 3/4 hp output at 61 GPM (@20 ft of head)?

Thanks!

[PoolDoc]

+ Restricting flow on a centrifugal pump does not cause overheating, so long as sufficient water passes through the pump, to prevent the water itself from getting hot. One GPM is sufficient to accomplish this.

+ Restricting flow to 1/2 of maximum will REDUCE electrical consumption.

+ The only way to measure the flow is with a flow meter, OR by discharging the flow into a container of known volume, and timing how long it takes to fill. BUT, you can 'feel' the flow, and tell when you've reduced flow rates by 1/2 or more.

+ Flow rate of the SuperPump depends on your piping AND on which "3/4 HP" pump you have: uprate or full rate.

[1PoolNoob]

+ Restricting flow on a centrifugal pump does not cause overheating, so long as sufficient water passes through the pump, to prevent the water itself from getting hot. One GPM is sufficient to accomplish this.

+ Restricting flow to 1/2 of maximum will REDUCE electrical consumption.

+ The only way to measure the flow is with a flow meter, OR by discharging the flow into a container of known volume, and timing how long it takes to fill. BUT, you can 'feel' the flow, and tell when you've reduced flow rates by 1/2 or more.

+ Flow rate of the SuperPump depends on your piping AND on which "3/4 HP" pump you have: uprate or full rate.

Interesting, I've never heard of restricting the output of the pump to get a desired GPM. This is the pump I'm looking at getting (ITEM # SP2605X7A) :
http://www.hayward-pool.ca/prd/In-Gr...93_.htmhttp://

How do I tell if it is a centrifugal pump and whether it is uprate or full rate?

So basically you can block/restrict half the output of the pump and it will cause the pump to work less, lower amperage consumed..? Does doing it that way, in essence, have a similar effect to that of a 2-speed pump?