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Pool Pipe Size.. 1.5 To 2inch And New Pumps


JeffT
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Hi All,

I am just curious what my best option is. I have a 18x36 pool that has 1.5 piping on the suction and return side. I have a new heater and also am looking at getting a new pump as mine is quite old. Most of the new energy efficent pumps out there or dual speed ones all seem to have 2inch piping which makes sense but just not sure what I should do. Can I just adapt from 1.5 to 2inch and use that through out my components and then bring it back to the 1.5 return ot the pool? Or should I just adapt it around the pump and leave everything else at 1.5? Or will that cause my pump to many problems and I should just stick with a basic but not as efficent pump that just has 1.5 in/out? I have an inline chlronator, sand filter and hayward 250but H series heater (New not hooked up yet)

Thanks for any replies.

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Hi All,

I am just curious what my best option is. I have a 18x36 pool that has 1.5 piping on the suction and return side. I have a new heater and also am looking at getting a new pump as mine is quite old. Most of the new energy efficent pumps out there or dual speed ones all seem to have 2inch piping which makes sense but just not sure what I should do. Can I just adapt from 1.5 to 2inch and use that through out my components and then bring it back to the 1.5 return ot the pool? Or should I just adapt it around the pump and leave everything else at 1.5? Or will that cause my pump to many problems and I should just stick with a basic but not as efficent pump that just has 1.5 in/out? I have an inline chlronator, sand filter and hayward 250but H series heater (New not hooked up yet)

Thanks for any replies.

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Your best bet is a combination of factors. You would do well to increase the size of your above ground piping to 2", as well as downsizing the pump horsepower. Increases in effeciency allow you to drop the hp rating, and still move more water. Increasing the piping size will allow you to utilize most, if not all, of the increased flow rate. You didn't mention your current pump hp, but normally you can downsize at least 1/2 hp and still see greater flow rates. You'll save on your electric bill as well by making these changes.

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Your best bet is a combination of factors. You would do well to increase the size of your above ground piping to 2", as well as downsizing the pump horsepower. Increases in effeciency allow you to drop the hp rating, and still move more water. Increasing the piping size will allow you to utilize most, if not all, of the increased flow rate. You didn't mention your current pump hp, but normally you can downsize at least 1/2 hp and still see greater flow rates. You'll save on your electric bill as well by making these changes.

Thanks for the reply. Current is a hayward super 2, 1HP. So if I increase like you say the above ground piping to 2inch I will have no problems with pump or anything since its more designed to suck from a 2" line vs the 1.5 I have and or too much pressure back to the pool when it gets dropped back from a 2 to a 1.5 on the return? Sorry I know that was way too long a sentence.

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A 1 HP Hayward is not going to have any problem at all moving enough water through 1 1/2 PVC, pumps are usually sized according to the size of the pool, the # of return fittings, the distance from the pump to the pool or the elevation of the pump verses the pool (head pressure) You should have gotten a manual that should give you more info or go online to Hayward's web site and you may get it there.

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Unless you're going to increase the pipe size to and from the pool as well, increasing the size of the face piping won't do much. The water still has to go through that 1.5 pipe back to the pool. Keep/repair/buy the 1 h.p. pump, It'll do fine. After all, the pool did ok to this point with the 1.5 pipe. Bush down at the pump. Or if you don't mind a little extra cost, go ahead and replace the face piping in 2". Just keep in mind that it's mostly cosmetic.

The new energy efficient pumps are not designed to increase your flow or to be more efficient by moving the water at a higher velocity, but to be ENERGY efficient. The idea is to run the pump longer at a lower energy draw (speed). I know that sounds a little strange, but it works.

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If you have multiple 1.5" pipes coming from the pool (skimmers, main drain), increasig the size of the aboveground piping will improve water flow. 1.5" pipe is rated at 51 gpm (gallons per minute) as a suction line and 63 gpm as a return/pressure pipe, at 8 ft. per second(APSP standards). Increasing the aboveground plumbing to 2" will allow the water to flow more easily thru the pipes, reducing the energy cost to move the water, whether your pump is "energy effecient" or not. You can force more water thru the pipes, but your cost (electric) to do so increases exponentially.

The newer pumps do move more water (gpm) than older designs. Your 1hp SuperII pump's design flow rate is around 65-75 gpm. It is a good pump and I agree, it can be repaired & will render good service. A newer pump, designed for a higher flow rate might not be desirable. As you decide whether to buy a new pump or repair your old pump, be sure to look at the gpm design flow rate, rather than the HP. An "energy effecient" rating is always good, but can be negated by incorrect piping.

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If you have multiple 1.5" pipes coming from the pool (skimmers, main drain), increasig the size of the aboveground piping will improve water flow. 1.5" pipe is rated at 51 gpm (gallons per minute) as a suction line and 63 gpm as a return/pressure pipe, at 8 ft. per second(APSP standards). Increasing the aboveground plumbing to 2" will allow the water to flow more easily thru the pipes, reducing the energy cost to move the water, whether your pump is "energy effecient" or not. You can force more water thru the pipes, but your cost (electric) to do so increases exponentially.

The newer pumps do move more water (gpm) than older designs. Your 1hp SuperII pump's design flow rate is around 65-75 gpm. It is a good pump and I agree, it can be repaired & will render good service. A newer pump, designed for a higher flow rate might not be desirable. As you decide whether to buy a new pump or repair your old pump, be sure to look at the gpm design flow rate, rather than the HP. An "energy effecient" rating is always good, but can be negated by incorrect piping.

Thanks so much for all the replies. In my situation my main drain connects to my skimmer and then there is 1.5 from the skimmer back so I would only be increasing if I did the piping between the pump/filter/heater/chloranator. Its back to 1.5 to the pool Would there be anypoint in doing that then? I am plumbing in a new heater as there wasn't one in before so the wee bit of flex pipe that is currently used wouldn't be a big loss to get rid of and start from scratch. That said I presume since my clorinator and filter both are for 1.5 connections it probably wouldn't really make any difference anyways.

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It can still improve the water flow thru the filter somewhat, but the benefit may not exceed the cost of doing so. The 1.5" suction pipe is your main limitation. As main circulation pumps are often oversized by the original installer, it's often possible to reduce the monthly cost of operation by some minor piping changes. Many people install a larger pump because of a perceived increase in flow, but in doing so, create a situation that costs them more than the benefit is worth.

Good luck!

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Its back to 1.5 to the pool Would there be anypoint in doing that then? I am plumbing in a new heater as there wasn't one in before so the wee bit of flex pipe that is currently used wouldn't be a big loss to get rid of and start from scratch. That said I presume since my clorinator and filter both are for 1.5 connections it probably wouldn't really make any difference anyways.

No.

Correct.

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  • 2 months later...

It would appear that JeffT and I are in a similar predicament. I have an in-ground Kidney Shaped fiberglass pool. All Sta-Rite filter and pump componets. The Filter and multiport valve have given up the ghost. After being repaired and such, we made the decision to replace the system.

When the pool was put in, all 1.5" PVC ran underground. As Jeff described, all of the new pumps are 2" pumps. So, I have purchased the following system components.

Filter: Sta-rate [s8S70]Sta-Rite System 3 Sand Filter - 3.4 SF / 68 GPM

Multi Port Valve: Sta Rite [18201-0200]Sta-Rite Multiport Backwash Valve for System 3 DE/Sand Filter

Pump: Sta-Rite [P6E6G-208L]Sta-Rite Max-E-Pro Pool/Spa Pumps - P6 Series - Energy Efficient 2 hp Pump

Pool Size: 9.5" deep(to water line)

Approx. 28000-30000 Gals

Integrated Hottub and Pool

All of these components are inline with the specifications of my pool and what we had before with the exception of one big detail. The plumbing is all 1.5" and all of the new items above are 2".

Question:

What are the ramifications if I neck down from 2" to 1.5" on this new pump? (Planning to run 2" line from Pump to filter as a side note.)

Are there any ways I can offset these issues?(ie: Take out the return jet directional balls?, Leave the Hottub inputs open? Etc)

Thank you, any assistance will be greatly appreciated.

Jeff G

Portland, OR

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Sta-Rite's website doesn't give the design flow rate for the pump, but it's very likely around 120-130 gpm at 40ft.head. Your filter has a design flow rate of 68 gpm. Staying at or below 8 feet per second velocity (exceeding this increases energy consumption but not flow rate) your 1.5" pipe will flow 51 gpm as a suction line or 65 gpm as a return/pressure line.

Installing this system will circulate your pool very well, but will cost you more to do so. You are limited by your existing plumbing, so you will have to reduce the pumps to 1.5". Removing the directional return fittings won't have any significant effect.

Likely side effects will be frequent filter damage or poor filtration, since you are pushing water thru the filter much faster than it's designed for, high energy cost related to the pool, and more frequent pump failures.

If it's possible, I would see if you could return the 2hp pump and purchase the 1hp pump. It will cost less initially, and cost less to run daily. You will have to run the system longer, but will ultimately cost you less to do so and you'll have longer life on your pump and filter.

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Thank you for the detailed response.

Just for clarification, I am trying to understand the information. The existing pump I have is a 2 hp pump with the exact same details at the new one. The only difference that i can see is the 2" intake and output. Both pumps have the same RPMs at 3450 and max amps at 11.2 as well as 230 voltage. Both the old and new replacement pump seem to have impeller dimensions.

So, for me not being an expert and I trust your information, how can a pump with the same rpms and HP ratings, produce a higher flow rate? I assume the impeller must have a different vein array to allow?

Thanks again for your information, Always something,

jG

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Great question. I hope lots of folks read this.

If you are purchasing the exact same pump that you currently have, then it was oversized to begin with. As with any other industry, modern equipment is more efficient than older equipment. 30 years ago, a 2hp pump would move around 80-90 gpm, whereas modern 2hp pumps can move up to 140 gpm. Different pump models are designed differently as well. For instance, a 2hp Hayward SuperII pump is rated for 115-130gpm, whereas the Super Pump moves 100gpm, both at 40 ft. head.

StaRite's own hydraulics schools have taught these principles for many decades. Unfortunately, many installers choose the "bigger is better" method, rather than acutally comparing flow rates & sizing pumps/filters correctly. Consumers don't know unless they are educated by the dealer.

I understand why you would question, but it's a very common error that is easily overlooked. HP isn't the real comparison to make - GPM flow rate for the pump, filter and existing plumbing is the real comparison. I don't have the phone number, but I"m sure Sta-Rite could confirm the sizing issue with the pump/filter.

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  • 9 years later...

I am also replacing my Hayward pump with 1 1/2" in and out with a Harris pump which is much less expensive (probably not as good a quality but I only want another 3-4 years with it). The Harris has 2" in and out. With a simple Yes or No, would there be any problems just stepping it down right at the pump from the 2" on the pump to the 1 1/2" lines?

Thanks

Mike

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  • 10 months later...
On 6/7/2019 at 6:30 AM, Mike W said:

I am also replacing my Hayward pump with 1 1/2" in and out with a Harris pump which is much less expensive (probably not as good a quality but I only want another 3-4 years with it). The Harris has 2" in and out. With a simple Yes or No, would there be any problems just stepping it down right at the pump from the 2" on the pump to the 1 1/2" lines?

Thanks

Mike

exactly my question.....is there an answer?

 

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  • 1 year later...
  • 1 month later...

I will be installing my new 33 x 18 AGP next week. 15,000 gallons. I bought a Hayward super pump VS and a Hayward C4030 quad cartridge filter. The pool wall has 1 skimmer and 1 return. I will be punching 2 holes at the other end of the pool for another 1.5" return and a 1.5 in supply. Basically, when I'm done with the installation, I will have two 1.5" returns( to the pool ) , One skimmer and one 1.5" supply( to the pump ). 

My question : The Hayward super pump VS has a 1.5" supply and return. Other than the skimmer, the pool is also all 1.5" fittings. The filter is 2". Does it make sense to plumb everything with 2". if everything is a bottleneck of 1.5" fittings ( except for the filter ), what advantage does running a 2" PVC pipe 33' down the side of the pool to step it down to a 1,5" to enter the side wall fitting. Same thing with the skimmer. the attachment for the skimmer is 1.5" and the pump intake will be about 14' away. Does it make sense to come out of the skimmer and and step up to 2" for about 12' to go back down to 1.5" to enter the pump. 

Thanks for any replies. 

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