Design flow rate vs maximum flow rate...

[cruzmisl]

Hi All,
I want to replace my existing 115v single speed pump to a 230V dual speed. My current 3.14sq ft sand filter (300lbs) states the design flow rate is 63gpm. My current pump flows 60gpm. I wanted to get the 1hp Pentair whisperflo but is has a high sf factor of 1.65 and flows 88gpm on high speed. Alternatively I could get the 1.5hp Superflo that flows 66gpm (using 50ft head for calc's).

I have 2 -1.5" suction lines and 3 - 1.5" returns that can easily flow the 88gpm (or I can have 1 suction and 1 return if I close valves - or any combo in between) of the whisperflo but I am thinking it may beat up my sand filter. I was planning on upgrading to a DE filter later but not right now. Since my pool is only 15K gallons (give or take a few K) I am thinking I may be able to get the 1.5HP superflo which will give good turnover at low speed (at least 1 time/day) and won't shag my current sand filter.

Any ideas?

Thanks,
J.

[mas985]

Why not the 1 HP uprated (3/4 HP full rated) Whisperflo two speed? You only need 31 GPM for an 8 hour turnover. At 50 ft of head, it has 70 GPM, half speed is 35 GPM. You will get an 8 hour turnover at low speed and 4 hour at high speed. Also, you will not need to change the power as it runs on 115v.

One other thing, if it is a temporary situation, you could put in a slightly closed ball valve near the filter to increase the head loss. If you run the head up to 60 feet, the 1 HP uprated pump will flow only 60 GPM. Then when you get your new filter, remove the ball valve or open it up.

[cruzmisl]

I thought the Whisperflo was perfect too (3/4HP) but really wanted to go to a 220V motor just because they tend to run a bit cooler. Wether or not it really makes a big difference, I don't know.

Other option is the 1HP Superflo which will flow about 55GPM. I hope after all this research the Supeflo is a good pump I Would really consider the 3/4 110 Whisper if someone can convince me there is no major reason to go to 220V. Less wiring I have to do.

Thanks!
Joe

[sock monkey]

Alternatively I could get the 1.5hp Superflo that flows 66gpm (using 50ft head for calc's).

How do you know how to figure ft head? I am trying to match a pump with a filter and can't read the proper GPM of the pump without knowing feet head...but I have no clue what this is.

[ytngt]

I can speak from experience...

My old 1.5 hp pump sprung a leak so I replaced it with a 1 hp single speed Whisperflow pump. At that time I had a hayward sand filter rated at 62 gpm (3.xx sqft). The 1 hp Whisperflow easily outperformed my old 1.5 hp pump but it was to much for my sand filter. After a backwash the pressure would start at 22-25 psi. Also I would get a little sand in the pool so I replaced the sand and checked the laterals, everything was ok. My only guess is the 1 hp Whisperflow flowed to much for my little 62 gpm sand filter and that it was pushing sand through the laterals.

This year I had the opportunity to replace the sand filter with a DE filter. Hindsight being 20/20 the sand filter was definately undersized for my 2" piping and 1 hp Whisperflow. The DE filter runs at 10-11 psi compared to the 22-35 psi the sand filter ran at. The only thing that changed was the filter!

If I had it to do all over again the only thing I would change would be a 2 speed 1 hp whisperflow!

For now you could buy the 2 speed 1 hp and just use the low speed (with your sand filter).

[CarlD]

Have you considered the 1hp 2 speed SuperPump from Hayward?

Mine's been running into its 4th season now, mostly on low, and I use it with a 200# Hawyard sand filter with no problems on either low or high.

It's a 220v pump and surely is PLENTY big enough for your pool and won't overwhelm your filter. I don't know Pentair, but I've never heard anything but good about them, I just know I'm DELIGHTED with my 2 spd SuperPump.