Pump sizing help for new inground design

[Drewskii]

When the bubblers are on, it seems a three port actuator on the return side is in order to provide the 30 GPM each bubbler requires.

I suppose another three port actuator on the suction side to divert suction to the dedicated suction line.

Another possibility is an actuator for a bypass around the filter when the bubblers are on to relieve the pressure on the filter?


I'm trying to figure out what the TDH is for my design.
I'm looking for values for the following if anyone can provide.

Friction Losses for:

34" three port trench drain
Hayward skimmers
3/4" and 1" return eyeballs
Colorcascade bubblers 15-30 GPM
Pad plumbing assuming 2.5" pipe, check valves and other values like gauges.
Cartridge filter- still confused about the how to size because of the the divergent flows for bubbler on vs bubbler off, bypass maybe?
Salt water chlorine generator
Anything else ?

Also, I'm confused about suction side cleaners. I assume the suction is off when the cleaner is not being used. When it is in use, what kind of friction losses and flow are typical?

 

[mas985]

When the bubblers are on, it seems a three port actuator on the return side is in order to provide the 30 GPM each bubbler requires.

I suppose another three port actuator on the suction side to divert suction to the dedicated suction line.

Another possibility is an actuator for a bypass around the filter when the bubblers are on to relieve the pressure on the filter?

All good choices although the suction line could be optional because that is generally a manual process.

I'm trying to figure out what the TDH is for my design.

Why?

Also, I'm confused about suction side cleaners. I assume the suction is off when the cleaner is not being used. When it is in use, what kind of friction losses and flow are typical?

Nearly impossible to calculate so I wouldn't bother. You just set the valve so the cleaner wheels have a certain number of revolutions per minute usually specified in the manual.

On the cartridge filter, I would size it as large as you can so you don't have to clean it very often. 250 sq-ft should be good enough.

 

[Drewskii]

I thought to interpret a pump chart one had to assume a TDH.

 

[mas985]

Not necessarily but it depends on your objective. Are you trying to figure out if the Intelliflo will deliver enough flow rate for the bubblers or something else?

Calculating head loss is not a trivial process and it is especially difficult for new pools because you don't really know how the plumber will install the plumbing and all the fittings that will be used plus not all of the equipment has published head loss data. So the best you can do is to get a rough idea of operating points.

But there is another way to look at the problem. The operating point for 90 GPM on the Intelliflo is 80' of head which is quite large and more head loss than what your system would experience. So there should be no problem at all supplying that flow rate.

 

[Drewskii]

I suppose the goal is not to buy too much pump.
Or too little...

 

[mas985]

With a 90 GPM requirement, you need a big pump so buying one too big is not really an issue. The Pentair Intelliflo VS and the Hayward EcoStar have the highest max flow rates of any pump so you can go wrong with those. For a two speed, I would not go any less than a 2 FRHP or 2.5 URHP which are basically the same the pump.

But because of the high flow rate requirements, you will be much better off with a VS, either the Intelliflo or Ecostar because you may end up needing three speeds. The lowest (~1000 RPM) for just circulation and filtering, a mid speed (1500-2000 RPM) for cleaner and skimming and the highest speed for the bubblers. So really, you don't need TDH calculations to come up with that conclusion.

 

[Drewskii]

Is the model number the IntelliFlo VS-3050 or is it a family of pumps?

 

[mas985]

Here are the pumps I was suggesting:

http://www.amazon.com/Pentair-Intellifl ... elliflo+VS

http://www.amazon.com/Hayward-SP3400VSP ... ds=Ecostar

 

[Drewskii]

Here is the piping, ex-pad, for review.

The bubbler pipe, 2.5 inch is extended to within 12" of the exit for each bubbler where it becomes 1.5 inch pipe.
Is the bubbler flow still essentially equal?

Return line pipes are 2" and 18" below the pool water line.

Do locations of the suction and return lines look ok for circulation?

Any other comments are welcome.

 

[mas985]

The bubbler pipe, 2.5 inch is extended to within 12" of the exit for each bubbler where it becomes 1.5 inch pipe.
Is the bubbler flow still essentially equal?

Yes

Do locations of the suction and return lines look ok for circulation?

Yes but what is critical is the location of the skimmers. Are one or both downwind?

Also, normally a pool your size would have a single skimmer. The more suction ports you have, the less flow rate each will get for a given RPM. So a single skimmer will work much better at 1000 RPM than 2 skimmers and a main drain all working at the same time. This doesn't mean you can't have all three and adjust the flows, you can. But I have found that using a single skimmer works much better than 2 skimmers when operating at low flow rates.

Also, I am not a big believer in main drains. They really don't do much and they have plumbing that goes under the pool so are nearly impossible to fix should it spring a leak. There many posts on this forum where main drains had to be abandon because of leaks. But they can be sealed after the fact too. Just something to think about. If you have a deep end greater than 8', a deep return would do much better with circulation.

You might want to read this: http://www.poolinspections.com/manuals/ ... drains.pdf

And watch this:

[youtube:t29da19h]0IOUGhuKkSM[/youtube:t29da19h]

 

[Drewskii]

Yes but what is critical is the location of the skimmers. Are one or both downwind?

According to wind roses for historical data they are.

Also, normally a pool your size would have a single skimmer. The more suction ports you have, the less flow rate each will get for a given RPM. So a single skimmer will work much better at 1000 RPM than 2 skimmers and a main drain all working at the same time. This doesn't mean you can't have all three and adjust the flows, you can. But I have found that using a single skimmer works much better than 2 skimmers when operating at low flow rates.

Also, I am not a big believer in main drains. They really don't do much and they have plumbing that goes under the pool so are nearly impossible to fix should it spring a leak. There many posts on this forum where main drains had to be abandon because of leaks. But they can be sealed after the fact too. Just something to think about. If you have a deep end greater than 8', a deep return would do much better with circulation.

The following led me to use two skimmers and a main drain.

There is a wide disparity in potential flow rates
The sun shelf combined with the stairs and bubblers may create unusual circulation patterns.
Main drain may enhance more even water temperature and chemical mixing.
Circulation is impossible to predict.
Some report vacuuming and particularly brushing is retarded without a main drain.
Water level drops below skimmers...no filtration.


As you pointed out, valves on each line make any solution possible. Seems like cheap insurance.

 

[Drewskii]

Below is my attempt at detailing the pump pad diagram for the pool in this thread.

Comments are welcome and appreciated.

 

[mas985]

With solar, you will want a check valve between the filter and the valve J4.

It might be a good idea to have the bubblers plumbed in after the SWG because if the bubblers are 100% on with the returns off, the SWG would not operate.

A check valve after the heater is not really necessary with a SWG.

 

[Drewskii]

With solar, you will want a check valve between the filter and the valve J4.

Is it worth the expense to put the solar fittings in as part of the original design or can it be added easily later? I suppose one disadvantage of installing it initially is the additional head loss without the benefit of the solar heat.

It might be a good idea to have the bubblers plumbed in after the SWG because if the bubblers are 100% on with the returns off, the SWG would not operate.

I have seen conflicting opinions on splitting the bubblers before or after the SWCG.
1) The split should occur before because the high flow thru the SWCG will prematurely age it.
2)Things may have changed since the post below...what do you think?

Flow sensors are not as reliable as one might wish, so it is recommended practice to make sure that the SWG is never turned on when the pump is off, typically by only powering up the SWG when the pump as power. If you have an automation system that integrates with your SWG, it does this same thing in a slightly different way, insuring the SWG is never active when the pump is off.It is common to put the SWG on the pool return line and not on other "feature" lines, though this is not normally required. The most common case is to not have the SWG feed the spa. Running a SWG at it's pool setting will be way too much chlorine for the spa. (Unless you have an automation system that compensates for this, which most do). Feeding just chlorinated water to a waterfall or fountain is wasteful as chlorine can evaporate out while the water is in the air. (Though this isn't really a major problem because you don't lose all that much chlorine unless it is a mister or other extremely small drop fountain.

3) At 80 GPM, and the bubblers require 90 GPM so I assume the flow at the SWCG is substantially above 90 GPM, a loop is required. It seems the loop can be eliminated if the split occurs before the SWCG?
[attachment=0:1r9udrwj]Capture.JPG[/attachment:1r9udrwj]

A check valve after the heater is not really necessary with a SWG.

No head loss from the heat pump without a back check valve?
Stagnant water in the heat pump or does it still create turbulence with no back check valve?

 

[mas985]

Those are all good points, I just wanted you to know that the SWG may not have enough flow while sending 90 GPM to the bubblers so the SWG could shut off. A SWG usually needs around 15-20 GPM so adding that to the 90 GPM and you have 110 GPM and I am not sure you will get that with your current setup with the VS pumps. If you are only using the bubblers when you swim but most of the time you don't have them on, then the way you have it should be fine. However, you could also send only 70 GPM to bubblers so you have enough left for the SWG. You may need to make a compromise somewhere.

 

[Drewskii]

Mark,

Could you respond to the remarks below?

Is it worth the expense to put the solar fittings in as part of the original design or can it be added easily later? I suppose one disadvantage of installing it initially is the additional head loss without the benefit of the solar heat.

No head loss from the heat pump without a back check valve?
Stagnant water in the heat pump or does it still create turbulence with no back check valve?

Here is the data for the bubblers, in my case, with 6" of cover. What do you think happens at 20 GPM with a 1/2" nozzle?
[attachment=0:14hgd05n]Capture.JPG[/attachment:14hgd05n]

 

[mas985]

Plume height should be proportional to the square of the flow rate but the water depth attenuates it some. Scaling the 3/4", 1/2" should be close to 30" high.

Is it worth the expense to put the solar fittings in as part of the original design or can it be added easily later? I suppose one disadvantage of installing it initially is the additional head loss without the benefit of the solar heat.

If you know for sure you are going to put is solar, I would say yes, it is worth it. The extra head loss should not be that much if you use the right parts. Jandy neverlube valves and check valves or equivalent only.

No head loss from the heat pump without a back check valve?
Stagnant water in the heat pump or does it still create turbulence with no back check valve?

You will have stagnant water in the heater with or without a check valve so I don't understand these questions. The turbulence doesn't change either when the flow is shut off to the heater. It would be about the same either way.

Normally one puts a check valve between the heater and chlorinator but a SWG is a little different and doesn't really require a check valve there.

 

[Drewskii]

Here is the latest revision to the plumbing design.
The pump is a variable speed.
The bubblers bypass the SWCG because of the high flow required (30 GPM per bubbler).
Each bubbler is individually supplied to control the plume.
The suction side is one skimmer (2 1/2"), one main drain (2 1/2") and one cleaner (1 1/2").
There are three returns (2").
There are three bubbler returns (1 1/2").
All pad plumbing is 2 1/2".

Thanks in advance for any comments, advice, or questions.

 

[mas985]

For the most part, it looks pretty good. The only suggestions I can think of are the following:

I would replace the tee between the skimmer and main drain with a three way valve and actuator. Main drains are really only useful as a water source for high flow rate features (i.e. when the bubblers are on). But for general circulation and for the lowest possible RPM setting, it would probably be best to just shut it off so that the skimmer has all the flow rate.

Although probably not entirely necessary, I would go with a 2" suction line for the cleaner instead of 1 1/2". The cleaner line should be fairly low flow rate but smaller lines can get more easily clogged and there is little downside to a larger line.

You might consider replacing the ball-valves with two-way valves like this:

Lastly, you might want a return over the shelf somewhere. Without a return there, debris will likely fall on the shelf with no way to clear it. A return over the shelf somewhere would help move the debris away from the shelf before it sinks and then the cleaner should be able to get it. I would move the return closes to the skimmer to the corner of the shelf so it pushes water across the entire shelf. In fact, moving the returns closer to the corners of the pool would help set up a circular flow pattern that might help prevent dead spots.