Converting Spa pump/filter for pond?

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Converting Spa pump/filter for pond?

Post by dacfor.. » Sat, 01 Feb 1997 04:00:00



        Potentiometers are fine for controling the speed of a Direct Current (DC) motor. Don't use one on an AC motor. They're variable resistors and reduce the voltage. An AC motor ran on low voltage will overheat and possibly burn out.
        If your pump is a centrifugal type (probably is) you can reduce the output by restricting the outlet side of the pump with something like a valve. Don'tshut it right off but you should be able to cut pump output by at least 50% safely.
Happy Ponding!          Ted Christensen

 
 
 

Converting Spa pump/filter for pond?

Post by David Putma » Sat, 01 Feb 1997 04:00:00


Quote:

>         Potentiometers are fine for controling the speed of a Direct Current (DC) motor. Don't use one on an AC motor. They're variable resistors and reduce the voltage. An AC motor ran on low voltage will overheat and possibly burn out.
>         If your pump is a centrifugal type (probably is) you can reduce the output by restricting the outlet side of the pump with something like a valve. Don'tshut it right off but you should be able to cut pump output by at least 50% safely.
> Happy Ponding!          Ted Christensen

When you start restricting the output of the pump with a valve, Doesn't
this make the pump motor work harder thereby shortening it's life and
possibley increasing electrical usage.

Also if you have a 1/2 horse pump that is pumping 1200 gph and you only
need 600<>800 gph. Seem to me that monthly elecrical bill wise it would
be cheaper to buy (dirty word) a 1/4 <> 1/3 hp pump that draws less
power.

 
 
 

Converting Spa pump/filter for pond?

Post by Jack Konrat » Sun, 02 Feb 1997 04:00:00


Quote:

> When you start restricting the output of the pump with a valve, Doesn't
> this make the pump motor work harder thereby shortening it's life and
> possibley increasing electrical usage.

Actually just the opposite Happens, David. I wish there was a simple way
to demonstrate this with a pond pump and easily available items... but I
can't think of any. If you have a hair dryer, try turning it on in the
"air only" mode, and then completely block the air discharge with your
hand. You'll hear the moter speed increase, indicating that it is doing
LESS work. If you had a way to measure the input current, it would
decrease under the blocked condition. From physics, you might recall
that work is the result of moving a weight through a distance. When the
pump outlet is restricted, less weight moves through the same distance.

Quote:
> Also if you have a 1/2 horse pump that is pumping 1200 gph and you only
> need 600<>800 gph. Seem to me that monthly elecrical bill wise it would
> be cheaper to buy (dirty word) a 1/4 <> 1/3 hp pump that draws less
> power.

This MAY be true, but depends on lots of efficiency-related factors in
the pump motor and centrifugal pump design. The bottom line is "how much
current does this pump draw when it is pumping water at this rate". If
you hold "this rate" constant, only then can you campare the current
drawn by pump A vs pump B.

Geez I wish spring would come... :)

Jack

--
"Is it true that the hours you spend on rec.ponds
don't count against your lifespan?"
                             Kellie Sisson Snider

 
 
 

Converting Spa pump/filter for pond?

Post by don cunningha » Mon, 03 Feb 1997 04:00:00




Quote:

> >> --
> "Is it true that the hours you spend on rec.ponds
> don't count against your lifespan?"
>                              Kellie Sisson Snider

        No, Kellie, that one belongs to pilots " The lord does not deduct the
hours spent in the air
        from your alloted time on this earth." Another pilot saying I like is "
It's hard to remember
        that you started out to drain the swamp, when your up to your ass in
alligators!"
        ( I don't do smileys so consider the above humor and forgive the vulgate
use of the language.)

                                                                don cunningham

 
 
 

Converting Spa pump/filter for pond?

Post by dacfor.. » Mon, 03 Feb 1997 04:00:00


        Great reply Jack! I was trying to compose a reply covering the same points when I saw yours.
        I do hope everyone understands that this applies to centrifugal pumps only. Fortunately, pond pumps are almost always this type. You will harm a positive displacement pump by restricting the output.
        You're impatient for spring! Here, on the Canadian prairies, we have quite a while to wait.

Ted Christensen

 
 
 

Converting Spa pump/filter for pond?

Post by Michael Dobb » Tue, 04 Feb 1997 04:00:00


Quote:

>         Great reply Jack! I was trying to compose a reply covering the same points when I saw yours.
>         I do hope everyone understands that this applies to centrifugal pumps only. Fortunately, pond pumps are almost always this type. You will harm a positive displacement pump by restricting the output.
>         You're impatient for spring! Here, on the Canadian prairies, we have quite a while to wait.

> Ted Christensen

I'm the orignator of this post. Can you tell me how I tell if my Spa
pump is also centrifugal? It's big and has 2.5" pipes running into/out
of it.

Mike.
*** Disclaimer: These are the opinions of the poster not Amgen Inc.***

 
 
 

Converting Spa pump/filter for pond?

Post by David Putma » Tue, 04 Feb 1997 04:00:00


Quote:

>         Great reply Jack! I was trying to compose a reply covering the same points when I saw yours.
>         I do hope everyone understands that this applies to centrifugal pumps only. Fortunately, pond pumps are almost always this type. You will harm a positive displacement pump by restricting the output.
>         You're impatient for spring! Here, on the Canadian prairies, we have quite a while to wait.

> Ted Christensen

Yeah right, I think it was Jack who got me in trouble with my wife. Was
it Jack who liken the pump to a hair dryer and how when you restrict the
air flow by covering it with your hand it speeds up?
Whoever it was thanks alot.
I don't have a hair dryer (not enough hair) so being bored I wondered
into her bathroom while she was drying her hair. "Let me see your hair
dryer"   'Okay it's on low but it still gets hot.'  " Sure sticking hand
over end"  Ouch!  but not much change in speed.  We'll try high 'She sez
that will burn you up close'  No Problem, I covered my hand with her
bath robe. Now she has a scorached robe and I'm in the market for her a
new robe.
Boy sure wished spring would get here or i'm going to have to go to
work.
david
 
 
 

Converting Spa pump/filter for pond?

Post by David Putma » Tue, 04 Feb 1997 04:00:00


Quote:


> >         Great reply Jack! I was trying to compose a reply covering the same points when I saw yours.
> >         I do hope everyone understands that this applies to centrifugal pumps only. Fortunately, pond pumps are almost always this type. You will harm a positive displacement pump by restricting the output.
> >         You're impatient for spring! Here, on the Canadian prairies, we have quite a while to wait.

> > Ted Christensen

> I'm the orignator of this post. Can you tell me how I tell if my Spa
> pump is also centrifugal? It's big and has 2.5" pipes running into/out
> of it.

> Mike.
> *** Disclaimer: These are the opinions of the poster not Amgen Inc.***

Call alocal dealer for that brand and talk to the repair people. If you
can't find a dealer email me with brand name, model # & serial# if
avail.
david
 
 
 

Converting Spa pump/filter for pond?

Post by Paul Unla » Fri, 07 Feb 1997 04:00:00


You are lucky you did not melt the over temp sensor
its a one time shot, it opens, the dryer stops and
thats the end of that story [dryer] :)

paul

Quote:
>Yeah right, I think it was Jack who got me in trouble with my wife. Was
>it Jack who liken the pump to a hair dryer and how when you restrict the
>air flow by covering it with your hand it speeds up?
>Whoever it was thanks alot.
>I don't have a hair dryer (not enough hair) so being bored I wondered
>into her bathroom while she was drying her hair. "Let me see your hair
>dryer"   'Okay it's on low but it still gets hot.'  " Sure sticking hand
>over end"  Ouch!  but not much change in speed.  We'll try high 'She sez
>that will burn you up close'  No Problem, I covered my hand with her
>bath robe. Now she has a scorached robe and I'm in the market for her a
>new robe.
>Boy sure wished spring would get here or i'm going to have to go to
>work.
>david

 
 
 

Converting Spa pump/filter for pond?

Post by RTal » Fri, 07 Feb 1997 04:00:00


There have been some interesting point raised in this thread.  You could
no doubt use your existing pump and filter, however they are probably
poorly suited to the specific needs of a pond system.  It the best case,
you would develop a system curve(determine what flow and head your system
needs), and find a pump curve that closely matches it. That was probably
done, when the spa mfg selected that particular pump.  Spas usually need
more pressure and less flow, and usually work on a 3450rpm motor.
Typically a pond can most efficiently be run, with a higher flow, and
lower pressure pump, usually a 1725rpm motor.  

You can restrict the discharge of most centrifugal pumps, without hurting
them, and usually this lowers the amp draw (but not allways).

You can tell if its a centrifugal pump by looking at its overall design.
A centrifugal pump takes fluid in through the eye of the impeller and
accelerates it through the impeller, where it exits near the volute and is
channelled to the discharge.  The nice thing about this type pump is that
you can let it run with the discharge blocked with out building up
extremely high pressures.

Do yourself a favor, and measure the amp draw of the unit, and compare
this along with your associated flow, to what it would cost you to use a
unit specifically designed for you application.  You may find that it will
be far less expensive to buy a pump that is better suited to your
application.  As a benchmark you could use 1/4 hp with 4400gallons/hour,
and an amp draw of 3.2amps at 115V. (By the way, you dont save any money
switching to 230V)

Hope this helps
Rod

 
 
 

Converting Spa pump/filter for pond?

Post by jwa1.. » Tue, 11 Feb 1997 04:00:00



Quote:
>    No, Kellie, that one belongs to pilots " The lord does not deduct the
>hours spent in the air
>    from your alloted time on this earth." Another pilot saying I like is "
>It's hard to remember
>    that you started out to drain the swamp, when your up to your ass in
>alligators!"
>    ( I don't do smileys so consider the above humor and forgive the vulgate
>use of the language.)

>                                                            don cunningham

Gee, and my dad said it was "Let not this sparrow fall" while flying
in IFR conditions (I follow roads for those sadly grounded people)
 
 
 

Converting Spa pump/filter for pond?

Post by jwa1.. » Tue, 11 Feb 1997 04:00:00




Quote:
>Actually just the opposite Happens, David. I wish there was a simple way
>to demonstrate this with a pond pump and easily available items... but I
>can't think of any. If you have a hair dryer, try turning it on in the
>"air only" mode, and then completely block the air discharge with your
>hand. You'll hear the moter speed increase, indicating that it is doing
>LESS work. If you had a way to measure the input current, it would
>decrease under the blocked condition. From physics, you might recall
>that work is the result of moving a weight through a distance. When the
>pump outlet is restricted, less weight moves through the same distance.

Not to be a smartass, but are you sure this correct ? I've seen
situations to the contrary, and in the case of a blow dryer, when you
stop the flow of air at the outlet, you set a whole different chain of
events in motion that have nothing at all or very little to do with
hydraulics. In a pump situation, and I have seen this in a spa and
pool situation, the restriction on the outflow DOES cause increased
load on the motor and therefore, uses more juice etc. Unless in that
particular case there was something else going on that I am not aware
of