Pond pump speed control

Gale Pearce wrote:
You can restrict the outflow side of the pump, but not the intake or
you will burn out your pump prematurely - I use a "ball valve" to
reduce the waterflow on my submersible pump on the line to my filter
Gale :~)

I've already got a restrictor and T-piece on the pump outlet so I can
control the output at present. Somehow it doesn't feel "right" to reduce
the flow this way. I can't help feeling that it's putting extra load on the
pump. As I have a reasonably hefty lamp dimmer kicking around, I was just
wondering if using a device like this would be more mechanically
"sympathetic" IYKWIM. (Probably complete nonsense I know).

Tim

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Remove the obvious to reply by email.

"Tim Downie" wrote in message
...
Gale Pearce wrote:
You can restrict the outflow side of the pump, but not the intake or
you will burn out your pump prematurely - I use a "ball valve" to
reduce the waterflow on my submersible pump on the line to my filter
Gale :~)

I've already got a restrictor and T-piece on the pump outlet so I can
control the output at present. Somehow it doesn't feel "right" to reduce
the flow this way. I can't help feeling that it's putting extra load on
the
pump. As I have a reasonably hefty lamp dimmer kicking around, I was
just
wondering if using a device like this would be more mechanically
"sympathetic" IYKWIM. (Probably complete nonsense I know).

Since these are just turbine pumps, there is no difference as far as the
pump is concerned as to the location of the restriction on either the input
or output. I would not use a lamp dimmer since these are typically just
triacs and have a spiky output waveform which will cause motor heating,
however a variable speed control for a ceiling fan should work fine. One
other aspect to be aware of is that many pumps use either a fan or in the
case of submersibles, water to cool the motor. In this case any restriction
of flow, either by speed control, or by restriction may result in some
heating and should be watched.

Jeff Lowe

"Jeff Lowe" wrote in message
...
snip
Since these are just turbine pumps, there is no difference as far as the
pump is concerned as to the location of the restriction on either the
input
or output.
snip

I have often wondered about that and assumed that by restricting the input
the pump would be able to empty the chamber faster then it could fill it
causes the chamber to be a mix of air and water, whereas if you restrict the
output, the chamber will retain more water and less air. Surely both ways
make the pump work a bit harder, but it seems to be restricting the output
is better for it then restricting the input.

BV.

It is generally best never to restrict the input of a pump. I did not get to
see the original pump type, but many explicitly spell that out in their
directions as it does for my Sequence pump. Try to "reuse" the pump pressure
in other ways - redirect part to a filter/waterfall. Restricting the pump on
the output side is the same as adding head pressure due to vertical pump
height, fitting losses, change in pipe diameter etc... All reduce flow
rates.
Tim

"Benign Vanilla" wrote in message
...

"Jeff Lowe" wrote in message
...
snip
Since these are just turbine pumps, there is no difference as far as the
pump is concerned as to the location of the restriction on either the
input
or output.
snip

I have often wondered about that and assumed that by restricting the input
the pump would be able to empty the chamber faster then it could fill it
causes the chamber to be a mix of air and water, whereas if you restrict
the
output, the chamber will retain more water and less air. Surely both ways
make the pump work a bit harder, but it seems to be restricting the output
is better for it then restricting the input.

BV.

In uk.d-i-y Jeff Lowe wrote:

"Tim Downie" wrote in message
...
Gale Pearce wrote:
You can restrict the outflow side of the pump, but not the intake or
you will burn out your pump prematurely - I use a "ball valve" to
reduce the waterflow on my submersible pump on the line to my filter
Gale :~)

I've already got a restrictor and T-piece on the pump outlet so I can
control the output at present. Somehow it doesn't feel "right" to reduce
the flow this way. I can't help feeling that it's putting extra load on
the
pump. As I have a reasonably hefty lamp dimmer kicking around, I was
just
wondering if using a device like this would be more mechanically
"sympathetic" IYKWIM. (Probably complete nonsense I know).

Since these are just turbine pumps, there is no difference as far as the
pump is concerned as to the location of the restriction on either the input
or output. I would not use a lamp dimmer since these are typically just

Cavitation is a real concern if you put it on the input.
This does cause RAPID wear on the impeller.

"Ian Stirling" wrote in message
...
In uk.d-i-y Jeff Lowe wrote:

"Tim Downie" wrote in message
...
Gale Pearce wrote:
You can restrict the outflow side of the pump, but not the intake or
you will burn out your pump prematurely - I use a "ball valve" to
reduce the waterflow on my submersible pump on the line to my filter
Gale :~)

I've already got a restrictor and T-piece on the pump outlet so I can
control the output at present. Somehow it doesn't feel "right" to
reduce
the flow this way. I can't help feeling that it's putting extra load
on
the
pump. As I have a reasonably hefty lamp dimmer kicking around, I was
just
wondering if using a device like this would be more mechanically
"sympathetic" IYKWIM. (Probably complete nonsense I know).

Since these are just turbine pumps, there is no difference as far as the
pump is concerned as to the location of the restriction on either the
input
or output. I would not use a lamp dimmer since these are typically just

Cavitation is a real concern if you put it on the input.
This does cause RAPID wear on the impeller.

Since we were talking about lamp dimmers I guess I assumed we were talking
fractional horsepower. I didn't think these capable of enough suction get
below water's vapor pressure at pond temperature. I mean that's 29" Hg. Of
course some ponds and pumps are bigger than others ;-)

Jeff

On Fri, 21 May 2004 17:05:22 +0100, in uk.d-i-y "Tim Downie"
strung together this:

I've already got a restrictor and T-piece on the pump outlet so I can
control the output at present. Somehow it doesn't feel "right" to reduce
the flow this way.

If you read the instructions on most pumps that's how it's supposed to
be done. And under high pressure it probably would put additional
strain on the pump, but not really a concern at low pressures.
--

SJW
A.C.S. Ltd.

Easy solution just screw a splitter onto it and divert the extra water to a
spitter or your water fall....MIKE
"Tim Downie" wrote in message
...
Is is possible to use a speed controller (like a light dimmer) with a
small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I
don't
imagine this would be a problem in this case.

Tim
--
Remove the obvious to reply by email.

"Tim Downie" wrote in message
...
Is is possible to use a speed controller (like a light dimmer) with a
small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I
don't
imagine this would be a problem in this case.

I'd suggest the following...

1. Get a new smaller pump, and sell this one on eBay. Your electric bill
will thank you.
2. Attach a short piece of hose, and a valve downstream from the pump. It's
not a problem to restrict the output of the pump. You don't want to restrict
the input.

BV.

In uk.d-i-y Benign Vanilla wrote:

"Tim Downie" wrote in message
...
Is is possible to use a speed controller (like a light dimmer) with a
small
pond pump?

I have a Bermuda 3000 (3000l/hr) submersible pump that's really a bit more
powerful than I need. The motor has a solid rotor that appears to be made
of a ferrite like material.

I know that speed controllers can cause overheating problems with some
motors but given that it's underwater with water bathing the rotor, I
don't
imagine this would be a problem in this case.

I'd suggest the following...

1. Get a new smaller pump, and sell this one on eBay. Your electric bill
will thank you.

Pumps may use less than sticker ratings.
I have several 600W submersible pumps, that are (IIRC) 3000l/sec, from
lidl.
I stuck a meter on them, and they come out at around 360W.