How do you calculate head?

[Rangeball]

Mike, Thanks for the link. I'll give it a look.

If you do not want to purchase a vacuum guage then you can assume that suction head is about 40% of the return head (only works for no solar or extra return features) so

Total head ~ 3.2 * Filter PSI

Thanks for the info.

By filter PSI I assume you mean what my filter gauge reads? Normal operation is 10 psi. So 3.2 x 10 psi = 32 head?

And right now my filter psi is 14 (lot's of cottonwood lately), so head has increased to 44.8?

Is that right?

[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.

[Rangeball]

By filter PSI I assume you mean what my filter gauge reads? Normal operation is 10 psi. So 3.2 x 10 psi = 32 head?

And right now my filter psi is 14 (lot's of cottonwood lately), so head has increased to 44.8?

Is that right?

Mark, on the bold-

Is that right? And if head has increase, why am I getting less flow at the return?

Thanks