Help with determining horsepower requirement of new pool pump

[mastac741]

My pool pump was broken by roofers the other day (threw a concrete tile at it). My now dead, old pump is a Pentair Whisperflo WFE-3.

It is a WhisperFlo WFE-3, 3/4HP 115/208-230V Pump Self Priming, High Flow with 2" suction & discharge ports 12.8/7.0-6.4 Full Load Amps, 1.67 Service Factor 41 lbs

I have an appoximately 20,000 gallon vinyl pool. There are 3 jets on each side making 6 plus the skimmer. For such a small pool, I feel that this was overkill and leads to decrease in pressure of the jets which leads to leaves just sinking instead of going to the skimmer.

I'm thinking of going slightly up on HP to 1.5HP. (This has a service factor of 1 so Total HP = 1.5 whereas the Pentair has a service factor of 1.67 so Total HP is 1.25 - I don't understand this, but whatever).

I'm thinking of replacing it with a Pureline 1.5HP (PureLine Prime Pool Pump 1.5 HP - PL2602 - INYOPools.com). I'm guessing my number of feet of piping is 50 feet. It seems like the performance seems less than the Whisperflo?



Vs



How can the flow rate at 50 ft of head be for the WFE-3 be 70 gpm and the other one whose HP is higher be 48?

I'm just trying to determine if I will have a more powerful pump or not. Any advice would be appreciated!

Thanks!

 

[ajw22]

Get a Variable Speed pump which is really Variable HP. Then you can dial in whatever flow rate that works best for your pool.

I also don’t think you need to increase the HP of your pump. That will not help you with your leaf problems.

 

[mastac741]

Thanks for the reply. It seems that I need more pressure. Variable speed pumps are nice, but they're expensive. I live in Colorado, and only open the pool for 5-6 months out of the year. I usually just have the single pump on for 8-10 hours a day and that's it. It seems like it would take a long time to make up the cost difference of a variable speed pump. I read some of the amazon reviews of the variable speed pumps and a lot of reviews say they die after 3 years. Prefer not to spend $900 every 3 years. Seems like single speed pumps will last longer because there's less to go wrong.

 

[ajw22]

A VSP can reduce your electrical cost to run the pump by 80% or more compared to a single speed pump. If it only reduces your electrical bill by $25 a month over the 3 year life you will have done as goid or better then with a SS pump. And chances are the pump will last more than 3 years ans save yiu more than $25/month.

 

[setsailsoon]

Mas,

Ouch! I'm picturing what could have been a nasty injury. I hope nobody was injured. So not all pumps are created equall just because they have the same sized motor. And even that gets tricky when you consider service factor. Pump case design, impeller size and optimization of both can greatly affect performance. I don't know the pricing but I'm guessing the lower performance pump is cheaper.

As to the leaf issue, there are a lot of factors that can affect this. Dominant wind direction, obstructions, split of pump suction between skimmer and bottom drain to name a few. If there are experts available on this topic I'm sure they'll weigh in.

If you want to learn more about pool pumps to make more sense of it I highly recommend you visit this post from 2007. It's one of the best compilations of pool pump and hydraulics I've seen anywhere. The author of the post is still on here.

I hope this is helpful.

Chris

 

[mas985]

Many people on the forum run their pools just fine on low speed of a two speed pump or lower speeds of a VS pump so really a 3/4 HP single speed pump is overkill for just circulation. I used to run my 20k pool on low speed of a 1/2 HP pump and the skimmer worked just fine. So you really don't need much to run skimmers. In fact, if you have too much flow rate, the debris can sometime move to quickly past the skimmer and it is not collected. Something else is likely to be the problem if the skimming is not working well. Perhaps you are not pointing your returns properly.