Pool Plumbing Problems

[quantumchromodynamics]

Bypassing the heaters are ok but if I bypass the filter and salt cell when I leave spa mode, what is the best way to route water back through the filter and salt cell when the pump returns to a low flow(Jandy epump)?

Put the bypass from just after the pump to after the equipment and the diverter valve on the spa return line. You would just open the bypass when you want to use the spa on high speed. Open the bypass while checking the flowmeter to make sure that you have 35 to 40 gpm going through the filter, heater and salt cell. Add a flow switch before or after the heater to make sure it does not run without sufficient flow. Close the bypass when you return to low flow.

I don't recall how the blower is plumbed. It never really worked either. I guess I shall see how he plumbed it when I dig it up.

The blower should go to some sort of air-line that feeds bubblers or a venturi jet fitting line. See this reference.

http://www.waterwayplastics.com/manuals/810-0037.0908.pdf

Do your pool design plans show how the blower is supposed to be connected to the spa?

[Mark]

One more thing to be aware of is that if you go with 4" suction and 3" returns plus bypass the pad, the flow rate acheived may exceed the best efficiency point of the pump by close to 40% on full speed which is a run out condition. This can put excess stress on the motor shaft and may lead to premature failure of the motor bearings. The numbers I posted above, assume going through the pad plumbing and both configurations are within 10% of BEP.

I think the bypass is still probably a good idea with high flow rates to save your filter but there is such a thing as too little head loss for pumps. If you decide to go this route, you may want to consider running at lower speed and/or having a throttling valve on the return side to reduce flow rates. But if you do either of those, then it really doesn't make sense going with 4"/3" plumbing. Even if you downsize the plumbing to 3"/2.5" you may still have fairly high flow rates. A rule of thumb is to target +- 10% of BEP but not to exceed +-20% of BEP. The 3"/2.5" plumbing is less than 20% but not by much and it would give you more than enough flow rate for the high flow jets. I estimate about 140 GPM @ 47' of head. But even that is on the far right of the head curve.

One more question. If you have this jet setup, the jet nozzles are 5/16" and only require 10 GPM each so your current setup should have worked properly even with the 2" pipe but it sounds like something else is still wrong. 5/16" nozzles would have produced about 25 PSI in the filter with the 1 HP NS and only about 10" hg. If the jet nozzles have been removed, the spinners will not work properly, PSI will drop and suction increase which may be opening the release valve. Have you checked to see that the nozzles have not been removed or even expanded in some way?

[Hobie]

That is a good way to do the bypass. Thankyou.

As far as the blower in the plans. There is no mention of how it is to be connected but the Waterway diagram does appear to be what I have. I will research a little more when I get home.

[quantumchromodynamics]

I think that the concern about having too little head for the pump can be addressed by adjusting how much the bypass is opened and by being able to control the speed of the Jandy ePump.

For example, the Jandy ePump will do 100 gpm at the following:

RPM................Head in feet

3450......................70

3000......................48

2400......................22

Therefore, if the desired flow rate is 100 gpm, and 100 gpm creates only a total head loss of 48 feet, we would choose 3000 RPM. If the head loss at 100 gpm is 59 feet, then we would choose about 3225 rpm.

The Jandy ePump is adjustable to any speed between 600 rpm and 3450 rpm. That makes it easy to select the exact speed that will give the best efficiency for the desired flow rate.

I think that using 3-inch for suction and return would be the best size for the piping. I don't think that going to 4-inch on the suction would give much benefit.

Note that piping size can be deceptive. A 4-inch pipe can carry the same amount of water at the same head loss as (6) 2-inch pipes. Therefore, going to 4-inch would be increasing your capacity by six times. Going from a 2-inch pipe to a 3-inch pipe will give you about 2.9 times the capacity

It would help to know more about the exact flow requirements of the jets. Also, if you could get head loss curves for the jets, that would help a lot. Contact Waterway to see if they have this information.

[Hobie]

So if I understand you correctly,

1. The plumbing at 2" for 95" and 15 elbows(both suction and return), the spa will not physically operate, regardless of some other possible leak or blockage.

2. Therefore, I need to replumb to a larger pipe for suction and return.

3. For energy savings and life of my epuipment I need a a 2 speed or variable speed pump. The variable speed epump will allow the exact rpm to operate the pool recirculation and spa flow for equipment specifications(flow rate through filter and aquapure in recirculation mode and heater and flow needs in spa mode). There is not a need to operate the pump at full capacity is there? A 2 speed pump might not be the proper curves for my plumbing, equipment and/or spa jet requirements. The extra performce of the pump should allow me to change spa jets to a higher flow requirement if I desire. Essentially replumb then with the flowmeter adjust pump rpm to give proper flow rates for each configuration.

4. Since I believe that I must replumb the system, the cost of increasing the size of pvc and fittings is minimal and should be recovered long term with a reduced electrical drain(reduced rpm) on the epump. I live in Florida and it is only a matter of time untill the electric rates trend upward towards California's rates.

This spa has been such a huge dissapointment and bother since it was built. I don't mind overengineering things so that I know it will work and I will never have another problem with it. I only want to do this once.

Thank you again all your help, guidance and expertise. I along with others really do appreciate it.

Steve

[Mark]

First, I don't believe that the internals and nozzle for that mini-jet assembly is interchangeable with anything else. So you may be stuck with that size. For a 5/16" nozzle, Waterway recommends 10 GPM for moderate strength and 12 GPM for a strong jet. So for 5 jets, that is 60 GPM at most.

#1 - Your current setup with the 1 HP NS pump should have provided 58 GPM @ 73' of head which would have been 11 GPM per jet. The strength of the jet should be moderate but working properly so yes, your current setup should work. Also, the suction for that would have been only 9.8" Hg., so it should not have opened the SVRS vent if that is really what you have. The bigger question right now is that your current setup should work but why isn’t it? I believe that air is entering in from somewhere that is causing the pump to lose prime which is the biggest problem. Fix that first, and you might find out that the jets are fine. Try plugging the air vent and see if things don't work better. Also, are you sure that it isn't the venturi air inlet? If not, do you know where the air inlet is; close to the spa or near the pad? If the air inlet is near the pad, then you need an air blower.

#2 - You would benefit with larger pipe but it may not be necessary to get things to work properly. You may find out you have a collapsed pipe somewhere which is restricting flow on the suction side so it needs to be replaced anyway.

#3 - There is no need to run the pump at full speed but if you don't, there may not be a need for very large pipe either. The whole reason to go with large pipe is reduce head loss at high flow rates. Running at 60 GPM or lower, really doesn't require that large of a pipe and under most situations 2" would be fine but at 95', 2.5" would have been a better choice.

#4 - I am not yet convinced that you have to replumb but again, it wouldn't hurt. As to the size that is up to you but see the analysis below.

BTW, did you verify that there is indeed a 5/16" nozzle inside of the jet? This is key to understand the expected performance of the spa. If you can confirm that, I can tell you within a reasonable amount of error, what kind of performance you can expect with each size pipe. I went ahead and assumed that it is a 5/16" orifice and ran some cases with various size plumbing. All of these cases assume the Jandy JEP 2.0 which I think you will be using no matter what. I also assumed that you would set the speed such you get 60 GPM no matter what setup you end up with.

Current plumbing (95'-2"/2"): 3360 RPM, 60 GPM @ 75.6' of head, 10.6" hg., 1678 watts (note that even this config should work)

Config A (85'-2.5"/2.5"): 2991 RPM, 60 GPM @ 58.4' of head, 3.7" hg., 1273 watts

Config B (85'-3"/2.5"): 2940 RPM, 60 GPM @ 56.2' of head, 1.7" hg., 1223 watts

Config C (85'-3"/3"): 2871 RPM, 60 GPM @ 53.2' of head, 1.7" hg., 1157 watts

Config D (85'-4"/3"): 2839 RPM, 60 GPM @ 51.9' of head, 0.5" hg., 1123 watts

The biggest benefit is going to 2.5" plumbing and each step above that is a modest change. Also, remember that each of these configurations has exactly the same spa performance. The biggest difference is how much energy they consume.

But again, it is really important to find out what the current problem is first. You might end up replacing all of that pipe and find out it is something to do with the spa jets themselves and have to tear apart the spa to fix it.

[quantumchromodynamics]

Here are a few questions I think are critical to proper design:

01) What jets do you have?

02) What is the minimum and maximum flow rate that the jets are supposed to have?

03) What is the head loss for the jets at the minimum and maximum flow rates?

04) Where does the blower air-line go? Does it go to a bubbler or does it go to the venturi feeder line?

05) What is the diameter of the blower pipe?

06) Is the vent you describe an SVRS?

07) If the vent is an SVRS, what vacuum pressure is it set to open at? (Most are set to open between 10-15 inches of mercury)

I think that Waterway should be able to provide the information about the jets. If necessary, you could mail the jets to them so that they can determine what jets you have and they could advise you what jets can be used as replacements.

As far as the plumbing goes, I think getting the (15) 90s out of the pipe should be done at a minimum. The plumbing size is really going to be dictated by the jet flow requirements and the jet head loss curves.

You may even be able to go with the 1.5 H.P Jandy ePump if the jets are only going to require 60 gpm and you get the total head loss to below 75 feet of head. The pump curve for the 1.5 H.P is only slightly less than the 2.0 H.P.

Also, note this important rule:

If 100% of the pump’s flow comes from the main drain system, the maximum water velocity in the pump suction hydraulic system must be six (6) feet per second or less, even if one (1) main drain (suction outlet) is completely blocked. The flow through the remaining main drain(s) must comply with the latest published edition of ANSI/ASME A112.19.8, the standard for Suction Fittings For Use in Swimming and Wading Pools, Spas, Hot Tubs, and Whirlpool Bathtub Applications.

For 2-inch pipe, the water velocity hits 6 feet per second at 63 gpm.

[Hobie]

The next couple of days I intend to check on those issues. When I have more infomation I will post again.

Thanks

Steve

[Mark]

Regarding pipe water velocity, here is a quote from Haestad Methods, a leading authority on hydraulics:

With these multiple complicating factors, there cannot be a single maximum velocity that is optimal in every situation. On the contrary, designing pipe sizes for velocity alone is not the correct approach with water distribution systems. The velocities are useful only for spot-checking network model output when locating bottlenecks in the system (that is, pipes with very high velocities, and therefore high head losses). The real test of a design’s efficiency is not velocity, but residual pressures in the system during peak demand times.

When checking designs for permissible velocities, some engineers use 5 ft/s (1.5 m/s) as a maximum, others use 8 ft/s (2.4 m/s), and yet still others use 10 ft/s (3.1 m/s). Because velocity is not the real design parameter, there is no simple answer. Rather, velocity is simply another parameter an engineer can use to check a design.

Velocity limits for pipe are somewhat arbitrary and there really is no absolute limit as to how fast water can flow through piping. The were originally developed for metal pipes to limit erosion which is not an issue for PVC pipe. The more important parameters for a plumbing design are head loss and energy efficiency. About the only place that velocity makes a difference in PVC pipe is in water hammer but for most pools, it is difficult to find a situation where water hammer can even occur since it usually requires very fast closing valves. In this post, I estimated a velocity of 8.6 ft/sec (86 GPM) would give a 100% failure margin in a typical 2" schedule 40 pipe at 105 F so even that value can be exceeded which typically happens in most pool plumbing without detrimental effects.

[quantumchromodynamics]

I believe that the 6 feet per second limit rule may be a legal limit in some cases. (At least as written or enforced by some jurisdictions). That is my primary purpose for noting it.

There seems to be some ambiguity in exactly what the rules are. I think that part of the problem is that many state and federal rules are written by people who do not understand exactly what they are talking about.

The rules are sometimes vague and confusing. They are often written by people who have misinterpreted the law, or misinterpreted the proposed guidelines from standards bodies.

My primary concern is that an inspector might interpret the rules or law to be that the velocity in the plumbing could only be a maximum of 6 feet per second. If they believe that that is the rule or law, then they will have the ability to enforce it.

The way that some rules are written it appears that that if all of the suction is being pulled from only the main drains, then the water velocity in the entire suction system has to be less than 6 feet per second.

I agree that, from a physical standpoint, that it is not always necessary.

Maximum velocity through any one drain pipe shall not exceed 6 feet per second assuming 100 percent of the total recirculation flow at peak flow conditions.- http://www.doh.wa.gov/ehp/wr/permit-poolplandetail.pdf

2.4 Flow Rate. The flow rate or water velocity for residential pools and spas shall be limited to 6 feet per second ((1.829 mps) when one of a pair of outlets is blocked and 3 feet per second (0.914 mps) during normal operation. - http://www.apsp.org/clientresources/docume...PSPComments.pdf

Piping – General

For new installations, the piping between drains must be sized to limit the velocity to six (6) feet per second.

This limit applies to the branch piping and all fittings between multiple outlets and the tee leading back to the

pump. If code requires a lower water velocity, comply with the code. See Chart 1 for information on pipe size

flow ratings at six (6) feet per second.

Acceptable Pipe Size for Maximum Recommended System Flow Rate Per APSP-7 (6 ft. /sec inch the Branch Line) - http://www.pentairpool.com/pdfs/StarGuardMainDrainIG.pdf

4.4 Water velocity. Water velocity in field fabricated piping is based on the maximum system flow rate (see 4.4.1). Maximum water velocity in branch suction piping (shown as bold lines in figures 1 – 14) shall be limited to 6 feet per second (fps) (1.829 mps) when one of a pair is blocked. In normal operation then, the branch suction piping velocity is 3 feet per second (0.914 mps). All other suction piping velocities shall be 6 fps (1.829 mps) for public pools or 8 fps (2.438 mps) for residential pools (shown as thin lines in figures 1 through 14). - http://www.wvdhhr.org/phs/pools/Virginia%2...th%20covers.pdf

The pipes must be designed to keep water velocity under 6 feet per second from the main outlet box with 100 percent pump action. http://www.tpchd.org/files/library/c706489e4f85605c.pdf

2.13.4 Water velocity through outlet grates shall not exceed 1.5 feet per second. Water velocity through

anti-vortex suction outlet covers shall not exceed six feet (6’) per second. Suction outlets exceeding

1.5 feet per second are permitted provided each suction outlet has a cover that has been tested and

approved for such velocities by AMSE/ANSI A.112.19.9M R96. The maximum velocity in the pump

suction hydraulic system shall not exceed 6 feet per second when 100 % of the pump flow comes

from the main drain system and any suction fitting in the system in completely blocked. The flow

through the remaining suction grate outlet or outlets shall not exceed 1.5 feet per second. http://www.stlouisco.com/doh/SwimmingPoolE...on%202%2013.pdf

(2) In post-10/01/99 pools and spas, water velocity in pipes in a pump-suction hydraulic system must not exceed 6 feet per second when 100% of the pump flow comes from the main drain system and any suction fitting in the main drain system is completely blocked. When 100% of the pump flow comes from the main drain system and one fitting is completely blocked, water velocity and flow rate at the remaining suction fittings must comply with the following. http://info.sos.state.tx.us/pls/pub/readta...=265&rl=190

If 100% of the pump’s flow comes from the main drain system, the maximum water velocity in the pump suction hydraulic system must be six (6) feet per second or less, even if one (1) main drain (suction outlet) is completely blocked. http://www.jandy.com/ePumpPdf/H0311700B.pdf

Some of the rules are specifically for commercial pools. Some of the rules mean that the flow rate at the main drain covers should be limited to 6 feet per second but are written in a way that could be interpreted to mean the entire suction system.

For suction, there is an absolute velocity that water can go for a given length and diameter of pipe. The suction cannot exceed 33.9 feet, and that creates a fundamental limit to the velocity of water moving through suction plumbing. For 100 feet of 2-inch pipe, the velocity at 33.9 feet of head would be 14.6 feet per second.

For pressure, at some point the pressure in the pipe would exceed its design rating. 2-inch pipe is rated at 280 psi at 73 F. For 100 feet of straight 2-inch pipe, the pressure would reach 280 psi at about 71.8 feet per second.

For all practical purposes, there are obviously velocity limits that are going to apply. There are legal and regulatory restrictions that apply in some cases.

However, I do understand and agree with your point that people should not just design around one single simplistic number.

Good design and engineering require that the designer understand all of the relevant factors that will give the customer the optimum long term solution.

I think that using guidelines can be beneficial for people who are installing plumbing but don't have the ability or inclination to do the necessary calculations.

[Mark]

From what I understand the ANSI/APSP-7 regulations were intended to be voluntary and rarely enforced for residential pools but mandatory for only public pools. Also, for dual main drains, 6 fps only applies to branch connection between main drains and not the pipe going back to the pad. The rest of the plumbing is limited to 8 fps for residential. This document has all of the details on page 5, fig 1. But again, these are voluntary specifications and only need to be followed if the city forces you to actually follow these rules. IMHO, I think they are bit overkill and are really for the worst on worst case but that is for the pool owner to decide.

But back to Hobie, based upon my calculations, the flow rate of 6 fps would not be exceeded if the target was 60 GPM (5 jets each requiring no more the 12 GPM based upon Waterway recommendations for the mini-jet). Attempting to replace the pipe in the main drain branch section under the spa without tearing out the spa would difficult and dangerous so that part of the plumbing would probably not change anyway. But again this is if you choose to follow these recommendations.

[Hobie]

Well, one problem sorted out. Regarding the spa jets the instructions specifically say lenght of internal pipe. Apparently the installer either cannot read or cannot measure(possibly both). He cut the pipe 1 inch too short which will not allow jets to spin properly. Also looking at the flow out of each jet, I think a manifold would be a good idea in order to assure equal flow from each individual jet.

Now the fun part. Digging......

[Mark]

Did you sort out the venturi intake location, pad or spa and do you have a blower if pad?

Also, did you confirm that the jet nozzles were installed?

[Hobie]

The blower is located with the other equipment at the pad. The Waterway mini jets are plumbed with 2"pvc and the air is injected at the same point. All the jet nozzles are there but the supply tube is about 1" too short.

Also as I dig down I found anothe 4 elbow plumbed end to end. Who knows what I will find next. I plan on putting 3"pvc suction and return and see how it operates. Then plumb in the SVRS and then redo the pad plumbing.

[quantumchromodynamics]

Well, one problem sorted out. Regarding the spa jets the instructions specifically say lenght of internal pipe. Apparently the installer either cannot read or cannot measure(possibly both). He cut the pipe 1 inch too short which will not allow jets to spin properly.

Are you talking about the 1-inch (diameter) piece of pipe with the nozzle and retaining ring that goes inside the 2-inch pipe? It looks like that piece can be unscrewed using a 5/8 inch socket. If you can unscrew it, you can replace it.

http://www.waterwayplastics.com/manuals/810-0008.0409.pdf

Also, can you turn on the blower to see where the air comes out?

[Mark]

Hobie,

Did you have the blower on when you did all of the testing and checkouts before?

Also, what about the SVRS vent. Did you try to run the spa jets (blower on) with that closed off (i.e. blocked)? That may have a problem as well.

[Hobie]

I have removed the 1"pvc insert that is about 1" too short. From what I can discern, he included the jet cap in his measurement. I have ordered new pieces and new jets. As far as the return plumbing, a manifold is a difficult thing to plumb to the Waterway system. I have cut into the water supply line 2 places and that should be the best I can do for a manifold.

My kids(helpers) and I dug about a 5' deep x 4' x 4' hole. My 8year old son loves this<G>. There were 3 pipes running under the spa. 1 for the drains, 1 for the spa bubbler and 1 for the SVRS(BTW, the pool line also has it's own SVRS pipe). The SVRS line ties in about 6-12" from the spa drain T. I cut the above ground SVRS/vent pipe and it does vent into the spa drain. I am unable to get any closer than 30" from the spa drain T so I am stuck with Spa drains 3'10" apart and midway a T (2"pipe). The SVRS pickoff is about 6-12" from that T. The pipe is right next to the gunite so I am planning on living with 30" of 2" and then expand into 3" to the pump. I found 2 medium landscaping rocks in the pipe.

As far as the blower. It has never worked very well either. The water has backflowed through the blower checkvalve. I removed it and capped it for the present. I will hook it up to blow out the water before I bury the pipes. None of the information I have posted had the blower working.

Tomarrow I will dig trenches for all the spa, vac and pad excavation. Then I will cut all pvc from heaters, filters and pumps. Then replumb with 2 1/2 pvc and all sweep elbows. Everything is ordered except the Jandy epump and the Jandy Aqualink firmware upgrade. I will hook up the Hayward NS pumps with a 15/16" shim underneath for the proper height so the inlet is the proper height. The outlet is easy to replumb after I get the new pump. I figure that way flow rates and other information can be decided to make sure the Epump is the right pump for me.

A question. Since I have the Waterway Mini jet(5 jet at 10gpm each), and flow is only 10gpm, 30" of 2" pipe prior to expanding to 3' to pump should not be a problem. Trying to get closer would pose a HUGE chore!

Steve

[quantumchromodynamics]

There were 3 pipes running under the spa. 1 for the drains, 1 for the spa bubbler and 1 for the SVRS

The three lines should be: 1 for the drains, 1 for the jets and 1 for the blower line. The SVRS should be connected near the pump. I'm not sure I understand what the "bubbler" is. Does the blower go to the bubbler or does the blower go to the venturi line, or both? What are the diameters of the pipes?

The SVRS line ties in about 6-12" from the spa drain T. I cut the above ground SVRS/vent pipe and it does vent into the spa drain. I am unable to get any closer than 30" from the spa drain T so I am stuck with Spa drains 3'10" apart and midway a T (2"pipe). The SVRS pickoff is about 6-12" from that T.

What is the make and model of the SVRS? I don't think I have heard about one that would connect like you are describing.

A question. Since I have the Waterway Mini jet(5 jet at 10gpm each), and flow is only 10gpm, 30" of 2" pipe prior to expanding to 3' to pump should not be a problem. Trying to get closer would pose a HUGE chore!

The 30" of 2-inch pipe should not be a problem. Based on the flow rate of 10 gpm per jet, total = 50 gpm, you could even use 2.5-inch pipe for the suction and return with no bypass if you wanted.

I think you can skip the bypass if you're going to keep the flow rate below 60 gpm. I recommend a 2-inch bypass if you want a total flow rate that is at or above 60 gpm.

Are the 10 gpm jets the best flow rate available to you? What is the maximum flow rate for those jets?

For the long runs, here are my recommendations for maximum flow rates:

2.067-inch pipe will give you up to 11.2 gpm per jet. (Total=56 gpm. V = 5.36 feet per second. Pipe head loss = 7.93 feet at an equivalent total straight pipe length of 150 feet). (Not recommended).

2.469-inch pipe will give you up to 18 gpm per jet. (Total=90 gpm. V = 6.03 feet per second. Pipe head loss = 8.04 feet at an equivalent total straight pipe length of 150 feet).

3.068-inch pipe will give you up to 31.8 gpm per jet. (Total = 159 gpm. V = 6.9 feet per second. Pipe head loss = 8.02 feet at an equivalent total straight pipe length of 150 feet) (Check with local regulations for the maximum water velocity for suction and return

lines.)

I think that you could use 2.5-inch PVC or 3-inch PVC depending on the total maximum amount of flow you think you will need. 2.5 inch will be plenty for the jets you are getting, but 3-inch will allow you to upgrade to a jet that has more than 18 gpm if one becomes available.

Can you provide a few pictures to help us see what your system looks like?

[Mark]

I wouldn't count on Waterway making anything new to fit that venturi tee. They have a history of using odd threads on each of their tees so the fittings are not interchangable in addtion to simply not making the parts anymore.

However, there are ways you can modify the jets to create different strengths. Jet dynamics work primarily on exit velocity and pressure. So even though a 5/16" jet may only 10 GPM, the exit velocity and pressure is still quite high and feels strong. A larger orifice requires more flow rate so the exit velocity and pressure feels the same. However, a larger jet will provide the pressure over a larger surface area so that is a benefit as well. You could drill out the 5/16" jet to a larger orifice but then you will need more flow rate per jet to get back to the same strength. I would stick with the same jet size and see if it works for you after the changes to the plumbing.You allways have the option of modifying them.

Note too, the jets will not have the same effect and strength if the venturi blower is not operating so that may be the reason, the jets did not feel as strong. Having the vent pipe at the pad with such long runs dicatates that you have a blower and that it works properly. Also, the SVRS would appear to be not operating properly so you should replace that as well.