Right now, both inlet and outlet hoses are 5/8" garden hose.
I am planning on going shopping tonight and buying reinforced 1" ID
hose for inlet (soft hose may collapse), and reinforced OR regular 1"
ID hose for outlet.
The length of the inlet section will be about 4 feet.
The length of the outlet hose will be perhaps 10 feet.
There will be no restrictions on inlet flow. The inlet hose will be in
the pool, weighed down by a small piece of concrete, in such way that
it will prevent it from "vacuuming" and sticking to some flat surface.
It is located under the slide, in a not so accessible place, so that
it would not suck in children's body parts. A concern with a 1" hose.
My main interest here is not even the increased flow -- the current
throughput is adequate -- but mainly reducing the load on the
motor. It gets quite warm during operation. The extra flow will be
merely a bonus.
If the pump is flowing more water then it is doing more work, therefore it
will be drawing more current leading to a hotter running motor. Use a clamp
on ammeter to see what it draws now and also what it draws with the 1" hose
installed. I don't gamble much, but I would bet on this one.
Shawn, if the pump is working against a restriction in the line (5/8"
hose in this case,) and is designed for 1" output, then it's sure
working hard against that restriction. Opening up the orfice (to what
it was more or less designed to do) might well drop the amperage use as
it won't have to work as hard to move more water through a less
Bill in Phx.Az.
Shawn's right on this one, as long as it's a centrifugal or constant
head pump. The pressure put up is nearly constant. Work and amps are
related to throughput. Look at a pump curve.
This doesn't hold for "positive" displacement pumps. Throughput will
be fairly constant, restricting the output will increase the pressure
in the pump, and draw more amps. Restrict it enough and you may open
a relief, either designed or otherwise.
On Tue, 7 Jun 2005 00:25:11 -0400, Shawn <shawn_75ATcomcastDOTnet> wrote:
Try this exercise. Take a drinking straw and try to breathe through
it. You will find it difficult and you will spend much energy getting
a little bit of air through.
Then take a 1" ID pipe and try breathing through that.
Your throughput will be much greater but you will work LESS.
Same applies to a pump. Working against restriction wastes energy and
In fact, I installed new hoses, reinforced plastic type, tonight. The
flow increased at least twice.
Apples and oranges. Your lungs operate as a positive displacement pump.
Your water pump is (I will bet) a centrifugal pump. Like a vacuum
Try this exercise. Turn on your shop-vac. Listen to the motor pitch.
Block the suction. Listen to the motor pitch.
If you measured the current, you would also notice that your vacuum
draws less current with the intake blocked. So does your centrifugal
water pump. Block the suction side of the pump and listen.
To lots of folks, this characteristic of centrifugal pumps is
counterintuitive. But it still is fact, counterintuitive or not.
:Apples and oranges. Your lungs operate as a positive displacement pump.
: Your water pump is (I will bet) a centrifugal pump. Like a vacuum
:Try this exercise. Turn on your shop-vac. Listen to the motor pitch.
:Block the suction. Listen to the motor pitch.
:If you measured the current, you would also notice that your vacuum
:draws less current with the intake blocked. So does your centrifugal
:water pump. Block the suction side of the pump and listen.
:To lots of folks, this characteristic of centrifugal pumps is
:counterintuitive. But it still is fact, counterintuitive or not.
Absolutely! A centrifugal pump is, approximately, a constant pressure
device, that pressure being determined by the density of the fluid and
the RPM and geometry of the pump. It does minimum work at zero flow
(total restriction) and maximum work when the flow is unrestricted and
the pump is accelerating large volumes of fluid to the speed of the
outer rim of the rotor.
I've burned out the starting relay on a sump pump by operating the pump
without sufficient restriction on its output. Reducing the diameter of
the discharge line from 1-1/2" to 1-1/4" solved the problem and brought
the current draw of the motor down within spec. I also have an old 1/4
HP belt-driven blower taken out of an old home heating furnace. It ran
for many years pushing air against the restriction of the ductwork.
When run without that restriction as an exhaust blower, the motor
couldn't get off the starting winding until I changed the pulleys to
reduce the blower RPM.
For a centrifugal pump, more restriction results in less work for the
Ya know, you could use a 1" hose and drill holes all over it. I mean
a ton of holes, so the hose becomes pretty much a mesh tube. That way
you'll protect the inlet, won't have too much suction at any one
opening, and it'll eliminate that chunk of concrete. Softer is better!
It'll pull most of the water from the end by default, but should
anything block that it'll draw through the sides without much effort.
B.B. --I am not a goat! thegoat4 at airmail dot net
I hate to have to say this, but such are the times we live in....
I hope your homeowner's insurance or renter's insurance has healthy
liability coverage. You might want to call them and confirm the limits and
restrictions on your policy.
I checked with my insurance agent. They do not have any exclusions for
pools. If something unexpectedly happens, we'll be covered. They will
fax me a summary of my insurance and will mail me the brochure with
the full policy.
I do not expect big trouble tomorrow, because the kids are big enough
not to drown in that very shallow pool, the pool is soft and the slide
is low. But you are right, it pays to be careful.
Your pump sounds`awful big at 1 HP. I moved lots more water than that
with a 1/2 HP shallow well pump. A smaller pump with a bigger hose or
more hoses is the way to go. But since you already have the pump, I
would use it till it croaks. But I WOULD add a couple of hoses, within
limits, the more water the better. Put a manifold on the pump, connect
all the hoses to the manifold. Do the same on the suction so you don't
starve the pump.
Here's an idea if you find that a larger (or multiple) hose(s) is/are
flowing too much water to the slide: add a T-valve or T-fitting and dump
some of the excess flow back to the pool (perhaps make it swirl the pool
water). That way, you aren't overworking the pump (by trying to force water
through a restricted hose) and you can control how much water goes down the
Good idea. I will buy a T fitting, maybe with a valve. At the maximum
flow of 720 GPH, that works out to a gallon every 5 seconds. You can
visualize it as a 5 gallon bucket of water emptied onto the slide
every 25 seconds. I do not think that the flow will be too much. If my
guess is correct, I will return the T fitting back to the store, if
you are right, I will avoid trouble tomorrow.
Well throw that idea in the trash. From the many well-informed posts on
centrifugal pumps, it seems that dumping excess flow back into the pool will
simply burn extra electricity (and perhaps your pump). So instead, you
should use a valve to regulate the amount of water to the slide.
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