Pool Pump Sizing

[mas985]

So is the air line ran all the way back to the equipment pad and just left open (unless a blower is added)? I think maybe that's where my confusion is. Also is there a hartford loop at each jet or 1 for the entire spa?

Yes, although you can put the air line inlet almost anywhere. Mine is at the edge of the deck about half way between the spa and the equipment. It is only about 10' from the spa so it doesn't "need" a Hartford loop and can clear the lines on it's own but it is always a good idea to put one in anyway just in case. The issue with air lines is that if they are really long and the entire pipe fills with water, when the jets are off, then it is almost impossible to clear the lines without a blower. On another forum, a builder mentioned that he was able to design an air line over 100' long without a blower. But of course he used a Hartford loop. BTW, where is your equipment pad relative to the pool location?

When you say "return loop" does this mean basically having a dedicated return run all the way back to the pump inlet with a valve separating each return before entering the pump (sorry trying to understand terminology)?

A "plumbing loop" is a completely separate loop of plumbing from the suction port through the pump to the return ports. Usually each plumbing loop will have a separate pump. A "separate return" may use the same suction lines and pump as another function but from the pump back to the water, the return lines are separated for individual control.

When doing automation I assume you have to have control over both the return and the supply side.

Only if you add actuators to the valves.

I assume it's probably a good idea for each water feature to have it's only supply valve as well especially if doing different sizes and types of water features (for example 2 different lengths of sheer decents)?

Yes

I'll have to ask the wife if she would like to have the water features run while in the spa or not

Even if she says no, assume yes. It is 100x more difficult to change things after the fact.

So in this case the spa would have it's only return and supply lines and they jets would operate independently?

Yes

When you said "if you want filtering for #3, #4, & #5 all at the same time" you basically mean if we want to have the spa heating, the water features on and circulating the pool we would probably need 3 pumps and 2 filters.

Yes

Here are some standard configurations: Jandy Valve Plumbing Schematics - INYOPools.com

 

[Tegguy]

Yes, although you can put the air line inlet almost anywhere. Mine is at the edge of the deck about half way between the spa and the equipment. It is only about 10' from the spa so it doesn't "need" a Hartford loop and can clear the lines on it's own but it is always a good idea to put one in anyway just in case. The issue with air lines is that if they are really long and the entire pipe fills with water, when the jets are off, then it is almost impossible to clear the lines without a blower. On another forum, a builder mentioned that he was able to design an air line over 100' long without a blower. But of course he used a Hartford loop. BTW, where is your equipment pad relative to the pool location?

If I had to guess about plumbing length it'd be around 70' from the spa. From the pool returns probably around 30'

A "plumbing loop" is a completely separate loop of plumbing from the suction port through the pump to the return ports. Usually each plumbing loop will have a separate pump. A "separate return" may use the same suction lines and pump as another function but from the pump back to the water, the return lines are separated for individual control.

I was following you untill the "a seperatereturn may use the same suction lines" What's the difference from a return line and a suction line? Maybe it would help if I drew up a schematic of our pool thoughts.

Only if you add actuators to the valves.

I guess I'm asking are actuators required/recommedned or do the return lines not change enough?

Even if she says no, assume yes. It is 100x more difficult to change things after the fact.

I think we're going to go 2 pumps on this.

Here are some standard configurations: Jandy Valve Plumbing Schematics - INYOPools.com

thanks[/QUOTE]

 

[Yinn]

If you going for a VS, get a full size VS pump (e.g. Intelliflo, TriStar 2.7) and none of this is going to mater. These pumps have more than enough flow rate for almost any water feature and you can dial it down to very low flow rates for just the SWG. Think of a VS pump as a variable "Size" pump. Sizing is no longer required with VS pumps.

I came across this when I was searching the forum about VS pump sizes. Is the reason for going with the full size just for simplicity and future-proofing?

I get that I can always turn it down, but if a 1.65hp VS motor is half the cost of the 2.7hp VS motor, would it make sense to step down instead of stepping up? (Currently a 2.0hp single speed motor @ 100 GPM)

 

[mas985]

There are other reasons. A larger VS pump will run at lower RPM for the same flow rate as the smaller VS pump which means less noise. Also, depending on the smaller VS, it may have less features than the larger VS such as automation integration (i.e. SuperFlo vs Intelliflo). Finally, there is the maximum flow rate difference that may be needed for spas and/or other water features. If none of those features are important to you, then the smaller version would work just fine.

 

[Yinn]

There are other reasons. A larger VS pump will run at lower RPM for the same flow rate as the smaller VS pump which means less noise. Also, depending on the smaller VS, it may have less features than the larger VS such as automation integration (i.e. SuperFlo vs Intelliflo). Finally, there is the maximum flow rate difference that may be needed for spas and/or other water features. If none of those features are important to you, then the smaller version would work just fine.

Thank you for the explanation.

After some efficiency upgrades to reduce head loss, my 2.0 currently pumps out 110GPM @ 15PSI directly out of the pump when I'm on my bypass circuit. It gets restricted down to 60GPM and PSI skyrockets to 33PSI when it goes through the filter, heater, solar, SWG. Which is why I was looking for a variable to tune it down and save some money.

 

[mas985]

After some efficiency upgrades to reduce head loss, my 2.0 currently pumps out 110GPM @ 15PSI directly out of the pump when I'm on my bypass circuit.

I am surprised the pump isn't cavitating at that operating point. But you do realize that with a single speed pump, lowering the head loss actually increases energy use. So while the GPM/Watt increases with lower head loss, you are still using more energy so hopefully the extra flow rate is doing something useful.

 

[Yinn]

I am surprised the pump isn't cavitating at that operating point. But you do realize that with a single speed pump, lowering the head loss actually increases energy use. So while the GPM/Watt increases with lower head loss, you are still using more energy so hopefully the extra flow rate is doing something useful.

It might have been, but I didn't keep it on the bypass loop so it's going on the normal loop at 60GPM @ 33 PSI right now. It's not doing anything useful, which is why I want to tune it down to 50GPM with a variable speed pump. I've got an electric cleaner. No spa. No water features. Just 3 return jets, 2 of which are on a 2" line and 1 on a 1.5" line. So there isn't much aside from filter, heater, swg that need the flow.

 

[Yinn]

There are other reasons. A larger VS pump will run at lower RPM for the same flow rate as the smaller VS pump which means less noise. Also, depending on the smaller VS, it may have less features than the larger VS such as automation integration (i.e. SuperFlo vs Intelliflo). Finally, there is the maximum flow rate difference that may be needed for spas and/or other water features. If none of those features are important to you, then the smaller version would work just fine.

So I took the advice and upgraded up instead of down. I went with the Affinity AVSS3 and replaced the impeller with the Jandy 2.7 instead of my current Jandy 2.0 impeller. I also replaced the seals. The VS is significantly more quiet, but I'm not getting the flows I was expecting.

At 60% Flow / 2070 RPM, I'm getting about 30 GPM. At 80% Flow / 2760RPM, I'm getting about 45 GPM. On MAX / 3450 RPM, it's topping out at 55GPM. I found the lower limit via the WPS on my aqua pure and RayPak heat pump and confirmed with a VISFlow flow meter. \\

While I don't need higher than 50GPM, it concerns me a little that I need almost max to hit that rate. I would think at 3450RPMs with a bigger motor the flow would be higher if anything. Are there any troubleshooting steps I should take to make sure it's installed correctly?

 

[JamesW]

What is the filter pressure at each rpm and gpm?

 

[Yinn]

What is the filter pressure at each rpm and gpm?

I took a couple of ranges. The numbers were slightly different from yesterday, but that may be how I'm reading the gauges. Pressure gauge is in 2PSI increments, flow gauge is in 10GPM increments.

1035 RPM (30% Flow) = 10 GPM @ 0 PSI
2070 RPM (60% Flow) = 25 GPM @10 PSI
2415 RPM (70% Flow) = 30 GPM @ 14 PSI
2769 RPM (80% Flow) = 35 GPM @ 18 PSI
3105 RPM (90% Flow) = 45 GPM @ 24 PSI
3450 RPM (100% Flow)= 55GPM @ 30 PSI

For reference, old 2.25THP Single Speed ran at 3450 RPM. Filter pressure was 33PSI @ 60GPM.

 

[JamesW]

The pressure is way too high.

When is the last time that you took the filter apart and cleaned it?

Also, check for scale in the SWG.

 

[JamesW]

I just noticed that this thread kind of got hijacked.

Please remember to start a new thread so that the original post doesn't get confused with subsequent posts.

Maybe a mod can move the posts to a new thread.