How do you calculate head?

[mas985]

Without a vacuum measurement, that is about a close as you will get. 32 is pretty low for head. Must be large pipes and a weak pump. Do you have a head curve for that pump? Just curious why the GPM is for that head.

[duraleigh]

Mark, Rangeball,

Yeah, my normal psi is 11....so 35tdh for my pool as well. I have a full-rated 1.5hp starite max-e pro, 2" suction pipe, and 2 - 1.5" return pipe.

I have always assumed mine (tdh) is low because my sand filter is so large....140gpm rating (950 lbs of sand)

That tdh on my pump curve works out to right at 100gpm.

[tenax]

holy crap! that is a big filter you have there...i can't even picture it! great beer keg!

[Rangeball]

Without a vacuum measurement, that is about a close as you will get. 32 is pretty low for head. Must be large pipes and a weak pump. Do you have a head curve for that pump? Just curious why the GPM is for that head.

Here's the data sheet and head curve PDF for my pump-

http://www.pentairpool.com/misc/pdfs...ynamo_pump.pdf

It's a 1 hp motor. It's also for an AG pool, and I have an IG. This is the pump that came with the pool when we bought the house, and when it burned out 4 years ago this is the same pump the pool store replaced it with (long before I started paying attention and asking questions ).

All my piping is 1.5". I'm trying to calculate GPM, which is why I needed to know the head

I have been thinking of a 3/4 HP whisperflow, but as long as this one is working, I don't need to spend the money.

[Rangeball]

Looks like 60 gpm, turnover in a bit under 6 hours. I run my pump 24/7. I'm contemplating cutting that in half, but the pool is spotless, so it may be cheap insurance

[mas985]

If you do go with a new pump, it will be probably more powerful than the one you have so a 3/4 HP is probably more than enough for you. Your head will likely increase as well as your flow rate.

[Rangeball]

When I talked to Pentair last year after I discovered I had an AG pump, they suggested a 3/4 hp whisperflow.

From what I've been able to tell, I don't know how much it would save me in electricity. The 1 hp dynamo pump I have is rated at 12 amps. I believe the 3/4 whisperflow is 11 amps. Am I missing something? This is all new to me.

[mas985]

I think both of those are at 115v if I am not mistaken so the power usage will be slightly lower for the new pump as well as your turnover allowing you to run the pump for a shorter period of time saving even more.

Have you considered a two speed pump? The low speed will save you even more. Even with doubling the turnover for low speed, you will still save ~30% in energy costs over the 1 speed pump. The extra $100 for the 2 speed would be paid off in a few months.

[cygnusecks]

Wouldn't it be most accurate to mount a vacuum gauge just before the pump inlet, and a pressure gauge just after the pump outlet? Also, I assume that you want the solar ON (i.e. not bypassed) when taking the readings, as this will slow the pump down the most.

[Rangeball]

I think both of those are at 115v if I am not mistaken so the power usage will be slightly lower for the new pump as well as your turnover allowing you to run the pump for a shorter period of time saving even more.

Have you considered a two speed pump? The low speed will save you even more. Even with doubling the turnover for low speed, you will still save ~30% in energy costs over the 1 speed pump. The extra $100 for the 2 speed would be paid off in a few months.

Thanks.

Yes, both have 115v motors.

I currently run my pump 24/7, so I'm getting 4 turnovers a day. I could cut my use by 50% going to 12 hours

I'd really like to try doing so, but I'm having the most trouble free year ever since owning the pool, and am afraid to fix it if it ain't broke.

Even though my pump is AG, I'll use it until it dies, as it's doing a fine job on my pool. Just trying to be prepared for that day, cause, you never know