Newbie with a pump question

[rockyboy]

Hi to everyone on the forum. I have so many questions I don't know where to start. However, browsing the equipment section brought one to mind. I have a pool that is to be started in the next few weeks. It will be an IG vinyl, 16x24x42 grecian true-L. The contract calls for 2 skimmers, 5 returns, dedicated suction line, two main drains (only one line) and 1-1/2 in plumbing. Contractor is recommending a 2 hp Pentair challenger but I want a whisperflo. Any recommendations as far as pump size/challenger vs whisperflo/1 vs 2 speed? My concern is that I am only going to get one shot at doing this right the first time and I just want to bounce what my contractor is suggesting against what this forum has to say. The pool will be large at around 33K gallons so I want to be as efficient as possible on the pump. I am concerned about the 1-1/2 inch plumbing providing enough flow to turn over the pool in a reasonable amount of time or having too big of a pump trying to slam the water through too small a pipe. Contractor says all pool and equipment fittings are 1-1/2 so 2" doesn't make sense. Any thoughts would be appreciated!

Rockyboy in OK

 

[JasonLion]

Welcome to TFP!

If each line has it's own 1 1/2" pipe and there is 2" pipe where they join up near the pump then it should be totally fine. There are pumps with 2 1/2" connections but most are 2". Using 2" pipe everywhere might give some slight advantage but with three suction lines and five returns I don't think it is significant in this case.

A two speed pump is well worth it. On low speed it will need to run twice as long, but even so will use only slightly more than half as much electricity. That savings can add up over the years, plus the filtering should be just slightly better on low speed.

A 2 HP pump is way too much if you don't have a spa or waterfall or anything like that. I suspect that a 3/4 HP full rated wisperflow would be more than enough pump, but hopefully mas985 will show up and make a detailed recommendation.

 

[rockyboy]

Thanks for the reply. I need to get some clarification on your recommendations. I am trying to remember what my neighbor's plumbing looked like a month or so ago (same pool and contractor). I think I remember the dual main drains being a single line. As for the other hoses I am not sure. Perhaps the skimmers meet up at the pool and have a single line back to the equipment. I am assuming that would make a difference. What would your recommendation be? I don't remember that much going on in the trench back to the equipment so my guess is that the joining/sharing takes place at the pool. The pool will have plenty of returns....5 on the pool wall/2 on the steps/ 2 in the buddy seat....all have their own valve at the equipment. That is why I am searching here since I have time to make some changes that would be cheaper now than later...if not impossible. Big difference between what you feel is a good pump size vs the contractor. No spa or waterfall although we may go to a pressure cleaner if the suction fails. That may not matter since most have their own booster pumps. Still, I don't want to have to run a pump 24/7 to turn over a large pool enough to keep it clean but I realize that the plumbing is usually the limiting factor no matter what size the pump is. Thanks in advance!

 

[mas985]

First, I would recommend you reading this to get an idea on what pipe size to use and pump HP.

Second, as a minimum I would recommend a least 2" lines and have separate suction lines going from the pool to pad for each skimmer and main drain pair for a total of 3 suction lines.

I would also have separate lines for your return eyeballs, steps and seats for a total of 3 lines pool to pad so that you can control the flow to each set separately.

With the above configuration, you could get away with 1 1/2" lines but 2" doesn't cost that much more and you can reduce head loss so why not. Also, most pool equipment are 2" and 2 1/2" so I am not sure what your PB is talking about.

As for pump size, if you have no spa or waterfall I would go with as low a pump HP as possible. I am not sure about the steps and seats as to what kind of flow those need but I suspect not much. If so, a 3/4 HP Whisperflo could still run a pressure side cleaner if the flow was directed entirely or mostly to the cleaner. Two speed would be a nice option and save even more money during normal cleaning cycles.

 

[rockyboy]

wow....that is a tremendous amount of information and even with a technical background, I have to admit that I got lost a time or two. I will need to give it another read. Just a couple of high level comments at this point and then maybe I can solicit help in nailing down the details later while I still have time. I am concerned that my PB is not sizing based on formulas but on just what he "has always done" in 20 years of building which doesn't mean it is correct. Please let me know if I am off base:

* at 34K gallons, I calculate that I would need a pump to deliver about 71 GPM for one turnover in 8 hours
* The PB put in a Pentair SD80 next door (I will have the exact pool) which shows 75 GPM max

The rate that I would need for turnover seems to be a pretty good match to the filter. However, that flow rate seems to be pretty high and I am not sure at this point how much head I will have and how that will effect the flow. I guess my point is that it looks like I will need a pretty sporty pump and I cannot make the connection to the whisperflo chart in your hydraulics post for a 3/4 hp being sufficient. I am sure that I got lost in the wilderness somewhere. Also, my runs appear to be much longer than the norms you used. I am trying to keep the equipment nearer the electrical service and tucked out of sight around the corner of my house. A scaled drawing of my proposed pool location would roughly give the following run lengths:

Suction (3 lines per your suggestion)
* Skimmers (single line) @ 105 ft max or 75 ft and 105 ft separate
* dedicated suction line for cleaner @ 85 ft max
* main drain @ 65ft (single line)

Return
* eyeballs (assuming that all tie together and return to pad as a single line) @ 150 ft max
* steps @ 125 ft
* buddy seat @ 60 ft

Again, these seem terribly long. I really wish I had paid more attention to the neighbors build but I do know that there is a valve for the drain, return, dedicated suction, buddy seat and steps. I am going with a Kreepy for now but I may change my mind depending on how well it works for the neighbor. No big water features although my wife is wanting 4 deck jets which I assume will be valved separately. There is the option to move the equipment a bit closer to the pool (around 30 ft max) without it being an eyesore next to the pool. My neighbors distance to pad is similar to ours but they do not have plans for a flow meter. Maybe I can talk them into one before the plumbing is finalized. The electric rates are not outrageous (yet) in OK but I am up for saving as much as possible since the AC units seem to run around the clock. Having said that, I am not opposed to running on low speed 24/7 and on high for cleaning if that would make sense considering the size of the pool.

Again, I humbly ask for suggestions and guidance. I am afraid the contract does not specify plumbing diameter but I am pretty sure my PB has said he uses 1.5" as a standard and I dont' recall different sizes for suction and return. I will check the neighbors sizes this afternoon but now is the time to make changes and absorb the cost up front. Thanks!

 

[JasonLion]

Those pipe runs are longer than average. That does make the 2" pipe more attractive and may affect the calculations. I am sure you can negotiate for larger pipes. If the contract doesn't specifiy it would be plausible for him to ask for more money, but he shouldn't mind doing it and it shouldn't be that much more.

The deck jets are in the category of water features that may require additional flow to work correctly. It partly depends on when you want them to be on and how much automation you are getting or turning of valves you are willing to do to turn them on and off.

The 3/4 HP Whisperflow will put out 75 GPM at a TDH of 45, which seems plausible to me (though mas985 will have a much more acurate opinion).

 

[mas985]

wow....that is a tremendous amount of information and even with a technical background, I have to admit that I got lost a time or two. I will need to give it another read. Just a couple of high level comments at this point and then maybe I can solicit help in nailing down the details later while I still have time. I am concerned that my PB is not sizing based on formulas but on just what he "has always done" in 20 years of building which doesn't mean it is correct. Please let me know if I am off base:

PBs are not engineers so you cannot expect them to work much with formulas. They tend to do things the way they have in the past and you really can't blame them for doing what has worked for them.

* at 34K gallons, I calculate that I would need a pump to deliver about 71 GPM for one turnover in 8 hours
* The PB put in a Pentair SD80 next door (I will have the exact pool) which shows 75 GPM max

Upsizing your filter is usually a good idea. The larger the filter, the more flow it will handle and the less you will need to clean it. So go with the largest your budget can handle.

The rate that I would need for turnover seems to be a pretty good match to the filter. However, that flow rate seems to be pretty high and I am not sure at this point how much head I will have and how that will effect the flow. I guess my point is that it looks like I will need a pretty sporty pump and I cannot make the connection to the whisperflo chart in your hydraulics post for a 3/4 hp being sufficient. I am sure that I got lost in the wilderness somewhere. Also, my runs appear to be much longer than the norms you used. I am trying to keep the equipment nearer the electrical service and tucked out of sight around the corner of my house. A scaled drawing of my proposed pool location would roughly give the following run lengths:

Suction (3 lines per your suggestion)
* Skimmers (single line) @ 105 ft max or 75 ft and 105 ft separate I would go with separate lines for each skimmer
* dedicated suction line for cleaner @ 85 ft max
* main drain @ 65ft (single line)

Return
* eyeballs (assuming that all tie together and return to pad as a single line) @ 150 ft max
* steps @ 125 ft
* buddy seat @ 60 ft

Again, these seem terribly long. I really wish I had paid more attention to the neighbors build but I do know that there is a valve for the drain, return, dedicated suction, buddy seat and steps. I am going with a Kreepy for now but I may change my mind depending on how well it works for the neighbor. No big water features although my wife is wanting 4 deck jets which I assume will be valved separately. There is the option to move the equipment a bit closer to the pool (around 30 ft max) without it being an eyesore next to the pool. My neighbors distance to pad is similar to ours but they do not have plans for a flow meter. Maybe I can talk them into one before the plumbing is finalized. The electric rates are not outrageous (yet) in OK but I am up for saving as much as possible since the AC units seem to run around the clock. Having said that, I am not opposed to running on low speed 24/7 and on high for cleaning if that would make sense considering the size of the pool.

Flow meters are not much compared to the cost of the pool so I would ask for it. Also, double check his design to make sure you are getting everything you want (pipe runs, valves, etc.). It is easy for him to change it now rather than after the pipe is laid.

Again, I humbly ask for suggestions and guidance. I am afraid the contract does not specify plumbing diameter but I am pretty sure my PB has said he uses 1.5" as a standard and I dont' recall different sizes for suction and return. I will check the neighbors sizes this afternoon but now is the time to make changes and absorb the cost up front. Thanks!

See comments above.

If you go with 2" pipe, I would say your distances are ok. With 1.5" pipe, you may want to shorten the distances. I put together a few scenarios based on the information you gave me and few guesses on other stuff.

Primary circulation configuration would be both skimmers and main drain fully on with the return eyeballs only. I assumed that the steps and bench will not be on all the time although you could do that.

Also, I assumed three suction lines (skimmer 1, skimmer 2, main drain) pool to pad for this analysis.

I assumed a 3/4 HP Whisperflo. The best efficiency point is at about 63 GPM @ 58 feet of head but remember that head loss can always be increased to hit the BEP so going with less head loss is always a good idea.

These are approximations only:

So with 2" line at current distance: 48 feet of head @ 73 GPM
So with 1.5" line at current distance: 67 feet of head @ 52 GPM
So with 1.5" line at 30' distance: 59 feet of head @ 62 GPM

All three configurations are within 5% of the BEP so that is not a big issue since overall efficiency is pretty flat in that region.

Also, do the steps or buddy seat need high flow rates for jet action? This will change the design requirements.

 

[rockyboy]

Roger that on the PB.

The SD80 is the largest in the pentair sand dollar line. Any suggestions?

Are you suggesting 2" all around or different sizes for suction/return?

the seat and the steps are simply additional returns and not jets and they would probably not be on all the time. Would there be a change in your recommendation if they were?

Still a bit fuzzy on the 3/4 recommendation probably because it is such a huge difference between what PB was going to install but I am sure I need to read your post again. I think I had a 1/2 hp pump on my 18 ft round pop up pool but you and Jasonlion seem to independently agree that the 3/4 whisperflo is sufficient. What about the benefit of a two speed version or do you feel it is necessary.

As for the deck jets...strictly a novelty that my wife would like to have. Probably located close to the pool and not sure how much water they need but suspect all would be plumbed to a single valve. Will this change any suggestions?

Finally.....what could I be overlooking that might have an adverse affect on your recommendations? And what do I tell the pool builder when I spec this small pump and he looks at me like I am stupid

 

[waste]

Hi guys! Just a few ideas from the peanut gallery.

Let me start by saying that I firmly believe in separating not only the skimmers but also the returns - the reasoning being that if the common line breaks you lose the use of everything going to that line whereas if they are separate you can just abandon the one line until it can be repaired. Also, separate lines allow you to 'fine tune' the performance of each line via the valves to get the action you want from each segment. It also allows better flow across the system.

When we install steps and 'buddy seats' they have venturi jets to entrain air - they need more flow to do the entraining properly. If you were to separate the 5 returns into 2 banks (one with 3 rets and the other with 2) you could you could kill the valve to one of them and probably generate the flow needed to entrain the air while still keeping some water movement, and therefore skimming action, in the body of the pool. I'm not sure how much having 4 instead of 3 return lines would reduce the head but it may be enough to keep the 1.5" pipe viable over the longer run. As Jason pointed out, stepping up to 2" pipe across the filter system will also increase the total flow (there are a lot of 'head increasers' in the filter system)

Congrats on the impending pool - I hope it's everything you want and remains Trouble Free!

 

[JasonLion]

There are a couple of things going on that I might be able to clarify.

First, the 3/4 HP full rated WhisperFlo is a great pump that moves more water for it's size than most any other pump. The way pumps are labeled can be very misleading. Some 3/4 HP pumps are signifcantly more powerful than other 3/4 HP pumps. For example the 3/4 HP full rated WisperFlo is really 1 1/4 brake HP while the 3/4 HP up rated WhisperFlo is just under 1 brake HP and some other manufacturers up rated pumps are even smaller, even though they are listed as 3/4 HP. The number you really want to look at is brake HP which is listed HP times the service factor. Above and beyond that the WhisperFlo moves more water for a given amount of electricity than the average pump.

Second, pool builders consistantly tend to oversize pumps. They want to show you a pool where the pump really moves the water around so you will be happy on day one. They also have discovered that people who don't know any better like to hear they are getting a large pump. We live in a bigger is better culture, so that seems to be the default assumption. If you don't work through the implications a larger pump sounds better than a smaller pump. They don't care what happens months later when you find out what the electricity to run that pump costs.

Larger pumps use more electricity to move the same amount of water as a smaller pump. Going with a smaller pump will save money up front and in the long run and it will filter better. The only risk with a small pump is that it might not be able to shoot the deck jets clear to the other side of the pool at the same time that all the returns are wide open.


Then there is pipe. The key issue with pipe isn't that fewer or smaller pipes won't work, they will work. The key issue is that most of the cost is in digging the trench, making the connections that go through the wall of the pool, and getting the plumber to show up at your site. The price difference for the different sizes of pipe is trivial and even the cost of making each thing a separate run is minimal compared to the total cost of the plumbing. Also, once the trench is filled in and the deck has been poured the cost of adding a pipe goes way way way up. It is so much better to get everything you might want plumbed in now and never have to worry about it later.

 

[mas985]

Roger that on the PB.

The SD80 is the largest in the pentair sand dollar line. Any suggestions?

I'm not an expert in filters but the Triton II line does have larger versions.

Are you suggesting 2" all around or different sizes for suction/return?

Yes

the seat and the steps are simply additional returns and not jets and they would probably not be on all the time. Would there be a change in your recommendation if they were?

It could depending on the peak flow rate you need and if you want to run all the returns at the same time.

Still a bit fuzzy on the 3/4 recommendation probably because it is such a huge difference between what PB was going to install but I am sure I need to read your post again. I think I had a 1/2 hp pump on my 18 ft round pop up pool but you and Jasonlion seem to independently agree that the 3/4 whisperflo is sufficient. What about the benefit of a two speed version or do you feel it is necessary.

With your pool, you could run the pump 24/7 on low speed and probably have it cleaner than a 12 hour run on high speed plus save about 30% in electrical costs.

As for the deck jets...strictly a novelty that my wife would like to have. Probably located close to the pool and not sure how much water they need but suspect all would be plumbed to a single valve. Will this change any suggestions?

Same answer as above. It could depending on the peak flow rate you need and if you want to run all the returns at the same time.

Finally.....what could I be overlooking that might have an adverse affect on your recommendations? And what do I tell the pool builder when I spec this small pump and he looks at me like I am stupid

As general guidelines for pool design: large pipes, large filter, small HP Pump. The only things that change this formula are high flow features: Spas, waterfalls, jets, etc. If high flow rates are not required, there is no need for a high HP pump.

I would turn the tables on the PB. It is your pool so make him justify the high HP pump instead of you defending the low HP pump.

 

[rockyboy]

Thanks to all of you for your valuable input. I am going back to the well one more time so if I understand the recommendations:

1. Go with a larger filter if possible (but would the sd80 work?) Next size up goes from 325 lb to 600 lb of sand...big difference.
2. Pump...I am assuming that we are talking the high efficiency/full rated 3/4 hp whisperflo. You are not recommending a two speed model...right? I really didn't see a 2 speed 3/4 hp but I did see a 1 hp.
3. 2" on suction and return lines with single lines/valves for each drain and skimmer (skimmers for sure) and a line/valve for the buddy seat, eyeball returns and steps.

Still not too worried about deck jets but I will ask what flow rate they need.

Am I missing anything?

Now I do have a question regarding everyone's comments about energy savings. I do understand that a smaller pump uses less electricity. According to the Pentair website, the high efficiency full rated 3/4 hp draws 6 amps at 230v compared to my neighbors 1.5 hp superflo (pn 340039) which draws 8 amps at 230v. The neighbor has the same pool and equipment so maybe you could do a cost comparison example for turning the pools over once or twice a day to demonstrate the savings. Assuming both will have 2"lines and both of our pumps will be 230v. Finally MAS985 commented about running a two speed pump 24/7 on low and saving 30% more than a 12 hour run on high. Sooooo....is there a two speed pump you are recommending or were you talking generalities? Starting to be thankful the rain set us back since I am having time to research.

 

[JasonLion]

Yes, we are talking about the WFE-3, high efficency 3/4 HP full rated WihisperFlo. It is rated to draw 5.6 amps at 230 volts and will move 75 GPM at a TDH of 45.

The two speed is not available in a high efficency version, so there is a smaller advantage than there would be comparing one vs two speed in a different model/brand of pump. The closest two speed would be the WFDS-3, which is only available in a 115 volt model. Converting to equivalent units it draws about 7.3 amps at 230 volts and will move the same amount of water on high speed. On low speed, again in equivalent units, it draws 2.35 amps and moves half as much water. You would need to run twice as long on low speed so the compariable numbers are WFE-3 (one speed) at 5.6 amps and WFDS-3 (two speed on low) 4.7 amps equivelent (run twice as long so equiv to twice the amps for the same time). So the two speed on low will use 84% as much electricity, but on high it would use 30% more.

If you were lucky enough to have 3 phase power already available at your main panel (almost no one does) you could use the WFK-3, high efficency 3 phase single speed, which only draws 3.6 amps at 230 volts and moves the same amount of water as the WFE-3.

Now the 1 1/2 HP SuperFlo also moves right around 75 GPM at a TDH of 45 but draws noticably more electricity, so it is not even worth thinking about. The one advantage is that it costs more than $100 less initially, but you will probably use that much extra electricity every year (or every month in areas with high electric rates).