The Pool Pro’s Guide to Pump Sizing Smarter

Episode Transcript
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SPEAKER_00 (01:03):
Hey, welcome to the Pool Guy Podcast Show.
In this episode, I'm going totry to give you some advice on
sizing a variable speed pump.
If you're thinking aboutconverting your single speed
pump to a VS Pump, or if youhave a VS Pump now on your pool,
you want to verify it's theright size.
This podcast definitely is foryou.

(01:23):
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Since every pool is different,sometimes it does pay to have a

(01:47):
professional look at your poolbefore you upgrade the pool
pump, especially if you wantedto do it yourself and you're
undecided.
Now there are some rules ofthumbs you can work off of as
far as pump sizing.
The most obvious rule is that ifyou had a builder install a pump
at your pool, they probablyinstalled the right size pump.

(02:09):
Usually they install the rightsize pump.
I've only ran to a few poolswhere I thought the pump was
undersized, and a few poolswhere I thought the pump was
definitely oversized for thepool size.
But generally speaking, theoriginal builder, when they
build the pool, will install apump with the correct horsepower

(02:30):
for your setup.
For example, if you have a spathat's maybe 20 feet from the
equipment area that's elevated,he may have put in a 1.5 or 2
horsepower pump to get the waterto the spa flowing nicely versus
a one-horsepower pump.
And conversely, if you have anolder pool, most of the time the

(02:52):
builder had to put in a onehorsepower pump because that's
really all that your breakercould handle.
Usually an older pool has thepump on a 120 volt breaker, and
there's no way you can putanything with a higher
horsepower because of theamperage.
So technically that pump may beundersized because they were

(03:13):
limited by the amount of voltagethey could use for that pump, if
that makes sense.
They couldn't put in a 1.5 or 2horsepower pump in that
situation because of the voltagethat was available at the at the
time they were installing it.
So that may be an exception tothe rule that the builder put in

(03:36):
the right size pump when hebuilt the pool.
Now, how would you size thesepumps?
Let me just start by saying thatyou can do a test for what's
called total dynamic totaldynamic head.
And this is basically theresistance or how much
resistance your particular poolsetup has in regards to the

(03:59):
efficiency of the pump running.
Now, is this really necessary inthe real world, like a backyard
pool?
Well, I mean you could you couldhave this done.
You have to put you know apressure gauge in front and also
on the return, and then you haveto see the difference in that
number, and you can calculatethe total dynamic head.
Most pool pros don't botherdoing that because most

(04:23):
residential pools don't reallyhave a very complex system.
Now, yes, granted, there may besome pools with a single pump
running the waterfall feature,the solar on the roof, different
things where there's lots ofelbows and lots of different
elevation differences.
But the main resistance is goingto be elbows in your equipment

(04:45):
area, and also the main thing isyour pipe diameter.
So if you have 1.5 inchplumbing, going to two-inch
plumbing on certain aspects ofyour equipment area, not
necessarily digging up the pooland replacing all the plumbing,
but certain parts of the poolwith two-inch plumbing can
drastically reduce total dynamichead or the resistance of the

(05:08):
water in your system.
So that's something to considerthat your plumbing size is
probably the biggest factor.
And then the other factor wouldbe how many elbows and fittings
and you know twists and turnsyou have before the water gets
to the return.
But it's really not a hugefactor in backyard pools because
typically the equipment ispretty close to the pool, maybe

(05:32):
you know, 10 or 20 feet away.
Now there are setups I've allI've also had these pools where
the equipment is like 50 feet or100 feet away.
This becomes a little morechallenging.
But the building usually puts ina pretty powerful pump in that
case for that to kind ofcompensate for the resistance of
the water or the total dynamichead resistance that you're

(05:54):
going to face with differentplumbing situations.
So, what I'm saying is that youcan get a scientific analysis of
your system done, and you can doit yourself in some cases.

(06:24):
If you go online and look at theforms, they'll teach you how to
get your total dynamic head, andthen you can use that to go on
the manufacture site and kind ofchart the pump.
Again, really not necessarybecause you can kind of just use
some standard rules of thumbsfor residential pools,
commercial pools, yes, bigprojects where they have

(06:46):
infinity spillways and waterfeatures and things like that,
or solar on the roof.
You may need to have this doneto make sure you have the right
amount of flow or a powerfulenough pump and the plumbing is
installed correctly.
But again, usually at the build,the builder will account for all
these factors from theirexperience of installing at

(07:07):
other build.
So let me touch on an aspect ofvariable speed pumps that you
kind of need to know when you'resizing, and that is that they
don't really have a horsepowerrating, HP rating.
So if you look at your currentsingle speed pump, you'll see
something on the label and it'sgonna say 1.5 HP, and then it

(07:27):
may show the amperage of thatpump.
Doesn't really matter at thispoint because the variable speed
pumps nowadays, a lot of themcan be dual voltage VS pumps,
and I'll go over that in aminute.
And that means that they can runoff of 230 or 115 or if whatever
you want to call it, 120 and240.
It's kind of weird that there'sso many different ways of

(07:47):
labeling the voltage.
But basically, you don't have toworry about the amperage as much
as the what they label the VSpumps with now, which is THP or
total horsepower.
So let me just explain that I'lluse Penta and I as an example
since they're pretty popular andit's pretty easy to kind of

(08:09):
correlate each one of thesePenter VS pumps with the total
horsepower.
So let's just say you get asuperflow VS, and let's say you
have an older one that's gonnabe 1.5 total horsepower, but the
newer ones, if you had onewithin the last couple years,
the total horsepower is actually2.2 now.
So the superflow VS has a 2.2total horsepower.

(08:31):
And if you have a 1.5 horsepowersingle speed pump at your
property, then this pump wouldbe perfect for you because you
could modulate it to be 1.5horsepower because the total
horsepower is 2.2.
So you could set the speed downto where you would get the same
kind of power out of it as a 1.5horsepower pump running at the

(08:54):
full 3450 rpms if that makessense.
So let me back up for a minute.
A single speed pump runs off of3450 rpms, and a variable speed
pump, of course, you can changethat speed, you can put it at
2100 rpms or 2800 rpms, so youcan actually match that 1.5
horsepower gallons per minuteflow rate with a 2.2 horsepower

(09:18):
VS pump.
So that's actually a perfectsize pump for you.
You can even get away with astraight 1.5 total horsepower
pump.
So if you do need to run thefull speed, let's say for a spa
so you can get the jets going,you can easily do that with a
1.5 total horsepower VS pump aswell.
Now, if you had a 2 horsepowerpump, you're still within range

(09:39):
with the 2.2 horsepower pump,but you may want to go to a
total 3 total horsepower pump,which would be the Intelliflow
3.
By the way, they also make a 1.5Intelliflow 3 pump.
Or you can just get the WhisperFlow VS, which is 2.6
horsepower, which is plenty ofhorsep total horsepower, I

(10:00):
should say, which is plenty whenyou're replacing a two
horsepower pump.
So basically, you want to try tomatch the current horsepower you
have now, either the 1.5 or 2horsepower to a VS pump that's
within the total horsepowerrange.
Now, I was speaking earlierabout the older pools.
Typically, they have 1.5 inchplumbing and they have a one

(10:22):
horsepower pump.
Which VS pump should you get?
Well, I wouldn't recommendgetting a three horsepower pump
because if the voltage is 120volts, it's going to modulate
that down anyway, and it's goingto run maybe off of 1.5 or 1.6
total horsepower, and you're notgoing to get the the full three
total horsepower because thatrequires more voltage.

(10:45):
The dual voltage pumps, as youget to the higher horsepower,
will just modulate the totalhorsepower down, and so you're
not going to get the again thethree total horsepower from
maybe an Intelliflow 3 pump, andyou might as well not even get
that in that case.
But if you have a 1 horsepowersingle speed pump now with your
pool, you can easily install a1.65 or 1.5 total horsepower

(11:11):
pump, and you have you'll haveno problem with that at all.
One thing you should also noteis that a lot of pumps are going
to say VS for variable speed orVSF variable speed and flow
pumps.
Basically, a VSF pumpautomatically adjusts their
speed to maintain flow foroptimal pool performance.

(11:32):
So they're a little bit smarterthan just your straight VS
variable speed pump.
And a VS pump just sets the runat different speeds based on how
demanding the pool task is.
Basically, a spa, or if you wantto have a cleaner running at a
different speed.
So that's the only difference.
There's really not muchdifference between a VS or VSF

(11:52):
pump.
It's just that the VSF pumpautomatically does some
adjustments for you, which againgoes back to the you know not
needing to really know yourresistance too much because the
pump will compensate for that.
And that goes into just aboutany setup in the backyard.
Most of the time, the builderwill put in a separate pump for
a waterfall feature, or thebuilder will install a booster

(12:15):
pump for a spa if the equipmentis pretty far away and he really
wants to get that power of thejets going and doesn't want to
rely on the main pump for that.
So I think sizing is basicallyjust finding out where your
current pump is and then findinga VS pump with the total
horsepower that matches that asclose as possible.
Again, one horsepower, 1.5horsepower pump, 1.65 is

(12:39):
perfect.
1.5 horsepower, you can get awaywith a 1.5 horsepower.
I'd rather you get a 1.65 or1.85 or a 2 total horsepower
pump if you have a 1.5 rightnow.
And if you have a 2 horsepowerpump, you know, a 2.6 or 2.4 or
a 3 total horsepower pump vspump is perfectly fine in your

(13:03):
setup, and you shouldn't haveany problems if you kind of stay
within those parameters.
You don't want to go down in thetotal horsepower because there's
a reason why you have a 1.5horsepower pump at your
property.
For example, my backyard poolhas a one point had a 1.5, and
so I went with a uh 3.0horsepower pump.

(13:25):
I could have gone with a 2.
You know, 2.0 or 2.5, whatever,but I just went straight to a 3
because I can run my pumpactually the match the 1.5
horsepower if I wanted to.
And of course I have two-inchplumbing, and the reason why I
had a 1.5 in was because I havea spa that's fairly far from the

(13:46):
equipment, and there's nobooster pump.
And so for that to kind of getthe power, the 1.5 horsepower
pump was installed originally onmy pool.
And then when I switched to VS,I just went straight to a 3,
which you can do.
I mean, I could have gone with a1.85 or a 2.2, but I went
straight to a 3 because it wasjust easier at that time.

(14:07):
They didn't have a lot ofdifferent choices when I when I
was upgrading.
They had a 1.85, 1.5, or 1.65,then they had a 2.7 or a 3.
And again, you can go bigger,you're not gonna have much of a
problem because you can changethe speed of these pumps to
mimic the speed of your old 1.5horsepower or one horsepower

(14:29):
pump.
Let me talk just a little bitabout the WEF efficiency number
here.
You're gonna see this a lotbecause the Department of Energy
kind of put this number on allthe pumps out there, and some
people push your push a VS pumpbased on the WEF number.
And I would just ignore anyonewho's telling you that you
should get this pump because ithas a higher WEF number.

(14:50):
The higher the number, the moreenergy efficient that pump is,
it's gonna save you some energy.
The way they kind of get thenumbers is that it's gallons per
watt hour.
So if the pump moves sevengallons per watt hour, it's
gonna have a seven wef number.
If the pump moves eight pointfive gallons per watt hour,

(15:14):
whatever that is, I have no ideawhat that is, you're gonna have
a 8.5 rating.
In a nutshell, these ratingsdon't make a huge difference.
For example, the Superflow VS israted with a WEF of 9, the
whisper flow is a WF of 8.4, andthe Intelliflow 3, depending on
if you get the 1.5 horsepower,it's a 7.1, or the 3 horsepower,

(15:38):
it's a 9.4.
The amount of money you'resaving over the course of the
year is pretty nominal.
I would say if you're going froma 9.4 down to a 8.4, you're
probably gonna save maybe$20 or$30 more a year on a little bit
of an efficient pump becausethere's not a huge difference

(15:59):
between you know seven gallonsper watt hour and eight point
five per watt hour, and thesavings is pretty minimal.
You know, it's not it shouldn'tbe a deciding factor, in other
words, what the WEF number is.
The best way to save energy isto run your pump at a lower
speed, and yes, a higherhorsepower pump, like a three

(16:20):
horsepower total horsepower VSpump, will move more water at a
lower speed than a 1.5horsepower VS pump, but it's
really nominal and you don'treally notice the difference,
and it's not gonna be somethingto be really concerned about.
If you're going from a singlespeed pump to a VS pump, no

(16:41):
matter which one you choose,you're gonna save money by
running that one at a lowerspeed or lower percentage of
output, and it's gonna save youmoney by doing that versus the
actual WEF number of the pumpthat you purchase.
One thing I do recommend if youdon't have a VS pump that has
the flow built in, like theIntelliFlow 3, you would have to

(17:04):
get a flow meter on your system.
This will help to maximize yourenergy savings.
I think the Flow Viz is my go-toflow meter because if you have a
Jandy check valve, you can justretrofit that in there.
And then I've placed them ondifferent parts of the pools
before the pump, after thefilter, you know, before the

(17:24):
heater, anywhere on your system.
It's not gonna be a hugedifference in measuring the
gallons per minute, in myopinion.
You may be off by two or threegallons per minute, but it's a
great way to know that if youput your VS pump, no matter what
total horsepower, let's just sayyou have a you know three total
horsepower VS pump, and you wantto know what to set it at for 40

(17:47):
gallons per minute, because youwant to get the right
circulation for your pool, andyou're just guessing otherwise.
And so with the flow vis flowmeter, you put it at 2100 RPMs,
and it'll tell you how manygallons per minute is going
through the system.
Let's just say, for sake ofargument, it's 40 gallons per
minute, then you put it to 1800,then it drops to 23 gallons per

(18:11):
minute, and you'll be able toadjust your speed of your pump
based on the gallons per minuteto maximize your energy
efficiency and also get theturnover necessary in your pool
set at that speed.
So without a flow meter, you'rekind of just guessing, you know,
what exactly is the speed.

(18:32):
For example, when I had a singlespeed pump on my pool, it was a
1.5 horsepower.
With the flow vis flow meter, itwas pumping about 65 gallons a
minute at the full speed.
So if I put my three horsepowerVS pump, you know, at 2800 RPMs,
let's say, I can probablyachieve that 65 gallons per

(18:52):
minute pretty easily, and evenmore at the three horsepower
rate.
And then just briefly, I'lltouch on the brands of pumps.
Truly, I think they're allpretty good.
You know, some people preferprefer Pentair or Jandy or
Hayward.
I'm gonna say that if you have aPenthair pump now, just get a
Pentair VS pump.

(19:13):
If you have a Whisperflow, thenI think the perfect VS Pump
would be the Pentair WhisperflowVS.
And then if you have a Jandypump, well, simply go with the
Jandy VS pump.
You may not have to do muchre-plumbing in the case of both
the Pentair and Jandy pump.
If you get the same kind of pumpwith the VS on the back, and

(19:33):
with Hayward, if you have aTriStar, just get the TriStar
VS.
It just makes sense to get thesame brand you have already.
Switching brands may not belogical, especially if you have
an automated system, the pumpcommunicates better with the
branded automated system youhave already.
So I'm not a big fan of goingfrom say a Jandy pump to a

(19:55):
Pentair pump or a Pentair pumpto a Jandy pump.
I would just say if you have aHayward pump, get a Hayward VS
pump.
If you have a Pentair pump, geta Pentair VS pump, single speed
pump, I should say.
And if you have a Jandy singlespeed pump, just get a Jandy VS
pump.
These manufacturers kind of alluse the same drives in some

(20:15):
cases, they all use the samesentry motors, so it's not like
there's a huge differencebetween one brand over the
other.
And they're all pretty reliablenow, and I would say you may
have some preferences with thecontrollers and things like
that, but at the end of the day,I think it's just easier to go
with the same brand you havethere now and put the same brand

(20:36):
in in the VS version.
And so, to recap to make it easyfor you, try to go with the
similar total horsepower VS pumpwith the one you have already,
and then don't really worryabout the WEF number, just be
more concerned with how longyou're gonna run at a lower
speed to save energy.
Always go up with the totalhorsepower and not down.

(20:57):
In other words, if you don'twant to go below your single
speed pump that you havecurrently, you want to stay
above that with your totalhorsepower, and don't worry too
much about the resistance andtotal dynamic head and all those
things.
I don't think it's supercritical for a residential pool,
and it's not something that youshould be obsessing about.

(21:18):
And if you're looking for otherpodcasts, of course, you can
subscribe to my YouTube channelMonday through Friday, and
there'll be a podcast there foryou.
Also, if you go to my website,swimmingprolearning.com, on the
banner there's a podcast icon.
I have over 1700 podcasts thereavailable.
And if you're interested in thecoaching program, you can learn
more at poleguidecoaching.com.
Thanks for listening to thispodcast.

(21:39):
Have a rest of your week.
God bless.

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