I think I need some help from the experts

[jugger2500]

We inherited a pool from a friend of a friend and I've just finished setting everything up and I am working on connecting the filter. However, just a day or two ago I came across a few posts that lead me to believe that the pump we have been given is oversized for our pool.

The pool is a 18' ft round above ground which makes it somewhere around 7,800 gal.

The filter is a Hayward Pro Series model s180t. It states the following on the label: effective filtration area: 1.75 ft^2, filtration rate: 20 GPM/ft^2, filtration and backwash design flow rate: 35 GPM, Maximum working pressure: 50 PSI.

The pump has several labels on it, so I am slightly confused by that. One label states Maxim and American Products on it (which I think might be a subdivision of pentair). But another label says Magnetek (maybe they make the motor that the pump uses?). Another label says "HP 1.5 SPL" which I am guessing means it's a 1.5 HP. And finally the last label with most of the vital information says: Volts: 115, Amps: 12.0, Hz: 60, RPM: 3450, AMB: 40 deg C, SF: ----.

I do know that the prior owner replaced the pump once (the old one fried when his wife ran it dry). He kept the same filter, but it sounded like he got a larger pump. So, now I am concerned the the pump is too large for the filter and may damage something, and I am also concerned the the pump is much larger than we would need for our pool. I would certainly like to avoid electric bills that are any higher than necessary.

In addition if it matters I have an Intex SWG on its way to me, and will be installing that shortly after I get it. I don't think that would affect any of this, but wanted to make sure it was known.

On another note The pump basket connection is about 20 in. below the skimmer basket and about 7.5 ft away. I am going to run Schedule 40 PVC from the pool to the pump pad and then use flexible PVC to do everything from there. My plan was to use 1.5" pipe the whole way but after reading about head loss I am contemplating upgrading some of the pipe. Does anybody out there think this is worthwhile, or should I just go with the 1.5" the whole way?

Also, if there is anything else I can do to improve anything I have mentioned please let me know. I like to do things right the first time, and just don't have the experience to know what else I should be doing at the moment.

Sorry for the long post, and thank you so much for any help that anybody can provide.

 

[jugger2500]

Attached is a plumbing diagram to help illustrate how I plan on doing all of the plumbing. While it is not to scale hopefully it helps.

As I mentioned in the previous post I was planning on using 1.5" schedule 40, but now I am wondering if I should upgrade to 2" everywhere and then use reducers where needed. But, I would like to get some feedback on this before I do it.

Again any help is appreciated.

 

[acamato]

In order to make a decision you need to know the GPM of the pump/system.

You need to add up your length of pipe + equivalent length of pipe for the fittings.
For the equivalent length of pipe for the fittings see: http://www.lascofittings.com/supportcen ... ttings.asp

Then go to:. http://www.lascofittings.com/supportcen ... ssCalc.asp to calculate your pressure loss of 1-1/2" vs 2".

Depending on your flow the difference could be great or it may be small.

Edit: I just read that the filter is designed for 35 GPM max. 1-1/2" PVC @ 35 GPM has 3.23 PSI per 100' of pipe loss. 2" is 0.94 PSI loss. That 2.29 PSI difference per 100'. I don't think the 1-1/2" will be a big deal. Also, you probally do not have 100' equivalent feet of pipe on the discharge, so you loss will be less.

 

[jugger2500]

Thanks for the help. I did stick with 1.5" pipe as according to my calculations I have about 70 ft equivalent of pipe.

However, I've been reading more about pump sizing and basically everything I have read seems to indicate that this pump is much larger than it would need to be.

Maybe someone can help me understand why there isn't a number for the SF on the label of my pump (just a bunch of dashes). Does that mean that it would be an SF of 1.0?

If this pump is over sized can I get away with just getting a new pump and keeping the same filter? How large of a pump should I be considering ? 1/2 hp? 3/4 hp?

Does anybody have a favorite online retailer to purchase a pump from? The prices the pool stores in my area get for just about anything is ridiculous.

Thanks for any help in advance.

 

[Guest]

The Maxim is an older Pentair pump that was sold under their American and PacFab brands. The Magnetek is a replacement motor from AO Smith, which is why it probably doesn't have a service factor on it. (They might have also been used as the orignal OEM motor, not sure of that, but Pentair does use AO Smith moters on it's pumps.) While you probably don't need a 1.5 hp pump it shouldn't cause any major problems with your setup. If I remember correctly, the SPL ones were uprated so this is actually a 1 hp pump. This is actually fine for the filter you have. The Maxims were made for AGP and have been replaced by the Pentair Optiflo pumps.

 

[mas985]

Assuming a total of 100 feet of equivalent pipe (I added some pipe for the return eyeball, skimmer basket and filter) and using the 1.5 HP Superpump as a proxy for your pump (1.0 SF), I get about 70 GPM @ 34 feet of head. Estimated filter pressure is about 10 PSI, what does your filter pressure currently read or have you not run it yet? Your pump could be less efficient but I doubt by that much.

You are already to the right of the best efficiency point on the pump's head curve so going to 2" pipe will lower head loss and move further to the right on the head curve which will increase flow rates and will probably make for a noisy pump and may even damage the filter.

 

[jugger2500]

Once again thank you everyone for all of the help. All of you and this forum are great.

Well, I have the pump connected but not the same way it will be permanently. It's currently using that cheap pool hose stuff. I am waiting until I pour the concrete pad (expecting to do that this week or this coming weekend) to connect to the plumbing that I've put in.

I doubt it helps, but with those pool hoses I currently see a clean filter PSI of 15. I can post again after the pad it poured and the filter plumbed properly.