Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

--
Chris Green
·

Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

On Thursday, 28 July 2016 13:35:42 UTC+1, Bob Minchin wrote:
Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

And stops freeze damage.


NT

On Thu, 28 Jul 2016 12:27:29 +0100, Chris Green wrote:

Why is it that pond pumps are always submersible ones?
They aren't
http://www.water-garden.co.uk/prod/p...us-pump-0-55kw
though once you get to that size then they are not exclusively pond
pumps.

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

Different markets, most of what are called pond pumps are smallish
things that can be safely dunked into pond and using a longish cable
connected safely to a supply without too much technical knowledge from
the user.
If it just for a fountain then often no extra plumbing is needed at
all. Maintenance will involve pulling it out occasionally and washing
down/back flush with a hose. The motor and its connections will be
manufactured easily by sealing them in at manufacture and if a
magnetic coupling is used as many do then that is it ,no servicing
possible but will last for years if it is a good make.
It will be bearings that wear anyway and very few people would bother
to replace those themselves.
Start going to chambers by the side ,plumbing to disconnect and seals
to maintain then I reckon you are leaving the world of simple Pond
Pumps and moving into the world of pumps generally which might appeal
to those with an engineering bent or background but beyond the
capabilities of many people who just want to buy something and use it.

I have a bit of both, Oase 12 DC pond pump which is still running a
few years over its 5 year guarantee,
For fun occasionally I run an old Lister domestic H1 similar to this
http://www.stationaryengine.org/H1_restore_5.JPG
just because it is nice to see something mechanical working .
Mine isn't quite as immaculate but works fine.

G.Harman

In article ,
Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.


It's the type of the pump. If you remember your basic science. Lift and
force varieties.

If you wanted one to to both, it would be a double pump so much more
expensive. Same with car fuel supplies.

--
*When companies ship Styrofoam, what do they pack it in? *

Dave Plowman London SW
To e-mail, change noise into sound.

On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.


Cheap.
All you need is a potted motor with an impeller in a case.
They are extremely reliable with only one moving part.

Chris Green wrote

Why is it that pond pumps are always submersible ones?

They arent always, but submersibles are easier to use much of the time.

I can see no good reason why the pump can't be external to
the pond as long as it's self-priming (only to a small extent).

Much easier to make and to maintain then.

Not really. Doesnt make a lot of difference to the making
and its easier to make a submersible self priming.

Easier to maintain in some ways when you can just take
it out of the pond when you need to do anything to it.

On Thursday, 28 July 2016 12:33:05 UTC+1, Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

--
Chris Green
·

The main reason is they're easy to install/remove/replace.
Also cheap to make and ideal for the situation (pumping out of open water unlike say central heating.)

On Thu, 28 Jul 2016 13:35:38 +0100, Bob Minchin
wrote:

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

Yet the ones I use with float switch and thermal overload cut outs do
seem to fail, just over a year pumping out a cistern which fills if a
soakaway cannot cope. I've tried several brands and they all seem to
fail with the stator shorting to earth.

This even though they are continuously rated in the spec sheet.

AJH

On Saturday, 30 July 2016 09:25:45 UTC+1, wrote:
On Thu, 28 Jul 2016 13:35:38 +0100, Bob Minchin
wrote:

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

Yet the ones I use with float switch and thermal overload cut outs do
seem to fail, just over a year pumping out a cistern which fills if a
soakaway cannot cope. I've tried several brands and they all seem to
fail with the stator shorting to earth.

This even though they are continuously rated in the spec sheet.

AJH

Maybe they'd survive on reduced voltage. If life weren't so short one could build something that would last a lifetime, perhaps using a bucket wheel.


NT

In message ,
writes
On Saturday, 30 July 2016 09:25:45 UTC+1, wrote:
On Thu, 28 Jul 2016 13:35:38 +0100, Bob Minchin
wrote:

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

Yet the ones I use with float switch and thermal overload cut outs do
seem to fail, just over a year pumping out a cistern which fills if a
soakaway cannot cope. I've tried several brands and they all seem to
fail with the stator shorting to earth.

This even though they are continuously rated in the spec sheet.

AJH

Maybe they'd survive on reduced voltage. If life weren't so short one
could build something that would last a lifetime, perhaps using a
bucket wheel.

I suspect *submersible* does not imply permanent immersion. I have a
cheap Italian made pump which I use to top up the garden pond from a
shallow well. Used a few times a year, this has now done about 15
seasons. It spends most of its time on a shelf in a shed.

The impeller seals may not withstand the pressure changes due to
seasonal thermal cycling.

Mind, there is also the very cheap (£25.00) pump which powers the
*gurgle* in our back yard. Five years of permanent immersion and very
intermittent use!


NT

--
Tim Lamb

On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

None of the explanations here cite the reason as pumping capabilities of
a centrifugal pump on different densities of fluid.

Simply the pressure at the edge of a vane is a function of rotations
speed, diameter of impeller and directly proportional to density.

Since the density of air is 1/800 of water the pressure of pumped
air/vacuum would not be able to overcome any height of water.

On 30/07/2016 10:36 AM, wrote:
On Saturday, 30 July 2016 09:25:45 UTC+1, wrote:
On Thu, 28 Jul 2016 13:35:38 +0100, Bob Minchin
wrote:

But they are simple impeller pumps and have almost zero self priming
capability.
It is easier/cheaper to solve the waterproofing than make a self
priming, continuously rated pump. It also deals with any cooling issues.

Yet the ones I use with float switch and thermal overload cut outs do
seem to fail, just over a year pumping out a cistern which fills if a
soakaway cannot cope. I've tried several brands and they all seem to
fail with the stator shorting to earth.

This even though they are continuously rated in the spec sheet.

AJH

Maybe they'd survive on reduced voltage. If life weren't so short one could build something that would last a lifetime, perhaps using a bucket wheel.


NT



Less chance of freezing, too?

On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?

I can see no good reason why the pump can't be external to the pond as
long as it's self-priming (only to a small extent). Much easier to
make and to maintain then.

Submersible - Easier to hide, less chance of it running dry if a pipe
splits, one less joint to leak, significantly quieter, fixes the water
draw-off point in the right place at the bottom of the pond rather than
a free-swimming pipe, easy to cage the pump to prevent ingress of
oversized solids...
I'm sure there are other reasons too like not such an issue if the
casing halves leak.
Easier to maintain as the inlet is the side that will block from weed
etc so no pipes to disconnect and you can see if it's blocked or not
just be lifting it from the water...

On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?



--
"Women actually are capable of being far more than the feminists will
let them."

On 05/08/2016 14:53, The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

That's not really a helpful answer, is it?

The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

--
Chris Green
·

On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.


A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water.

No, it just needs a step down transformer somewhere.


A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.



--
"Women actually are capable of being far more than the feminists will
let them."

On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

I am aware of some fuel pump motors running in fuel, but then the fuel
is generally non-corrosive and a good insulator. Water is neither,
especially pond water.

In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket. Mine has been
quite happy for the last 4 years

--
from KT24 in Surrey, England

On 05/08/16 18:17, Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

IN my model plane days it was the standard way of bedding in the brushes.

https://www.youtube.com/watch?v=kujrWwJfi0k
https://www.youtube.com/watch?v=VBqMCqeS9LA
https://www.youtube.com/watch?v=YS1eH_YTD70

I am aware of some fuel pump motors running in fuel, but then the fuel
is generally non-corrosive and a good insulator. Water is neither,
especially pond water.

Dont need a good insulator at 12V.

The DC resistance of a small 6-12v DC can motor is way less than an ohm.

Even under power with any load its not much greater than than an ohm.

even salt water is a lot less conductive than that.



--
A lie can travel halfway around the world while the truth is putting on
its shoes.

On Fri, 5 Aug 2016 17:48:05 +0100, Chris Green wrote:


Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Most of the smaller pond pumps have a motor totaly encapsulated in
plastic at time of manufacture. The connection to drive the impellor
is a magnetic coupling. There is no shaft or gland to wear out and
start leaking which is the weakness of any pump witha mecahnical shaft
from motor/engine to pump impellor.

G.harman

On 05/08/2016 18:31, charles wrote:
In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket.

This thread was about motors running directly in water, with no
waterproof jacket.

"Fredxxx" wrote in message
...
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will run
whilst immersed in water. I haven't found one yet.

Have a look at bilge pumps sometime.

I am aware of some fuel pump motors running in fuel, but then the fuel is
generally non-corrosive and a good insulator. Water is neither, especially
pond water.

Pity about bilge pumps.

"Fredxxx" wrote in message
...
On 05/08/2016 18:31, charles wrote:
In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket.

This thread was about motors running directly in water, with no waterproof
jacket.

Like hell it is. It is actually about submersible pumps.

On Friday, 5 August 2016 18:46:09 UTC+1, wrote:
On Fri, 5 Aug 2016 17:48:05 +0100, Chris Green wrote:


Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A

Tell that to the folk that use industrial electrode heaters, kettles, washing machines, dishwashers, etc etc. It's just something we tell little children.

submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement,

of course it does


NT

On Fri, 05 Aug 2016 19:03:33 +0100, Fredxxx wrote:

On 05/08/2016 18:31, charles wrote:
In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket.

This thread was about motors running directly in water, with no
waterproof jacket.

I'm not sure how you've come to that conclusion. The OP never mentioned
motors running directly in water without any waterproofing. He was just
querying why submersible pond pumps seemed to be so common compared to
the use of external self priming pumps.

The answer to *that* question, btw, has already been mentioned but I'll
restate it he The reason for this choice of 'pond pump solution' is
quite simply down to 'cost effectiveness'. When you can eliminate shaft
seals and use a magnetically coupled impeller, it becomes a simple Job
to completely protect the high voltage motor windings from water ingress
via the static seals used for the cable conductors, especially true when
the pressure differential is no more than a tenth of a Bar or so.

The design of such submersible pumps lends itself both to mass
production and minimal BoM costs. When you need to protect a motor from
water ingress for use outdoors even when it's *not* submerged anyway,
it's a relatively small step to go from "rainproof" to "waterproof to a
depth of 1 metre" (or so maximum) once you've eliminated the need for
shaft seals.

Once you've produced a pump that can be submerged, you've eliminated any
need to add the costs of the parts required to make the pump reliably
self priming onto the BoM costs.

Long story short, submersible pumps are both cheap and reliable (only
one moving part), hence their 'popularity'. Plus, as was pointed out,
being submerged, more protection against the risk of freezing damage. :-)

--
Johnny B Good

In article ,
Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Wonder just how long a pump motor which wasn't waterproof would last when
left outside in all weather? Or were you going to build a special pumping
house for it?

--
*Seen it all, done it all, can't remember most of it*

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 05 Aug 2016 18:46:07 +0100, damduck-egg wrote:

On Fri, 5 Aug 2016 17:48:05 +0100, Chris Green wrote:


Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from the
'electrical' end into the 'pump' end.

Most of the smaller pond pumps have a motor totally encapsulated in
plastic at time of manufacture. The connection to drive the impeller is
a magnetic coupling. There is no shaft or gland to wear out and start
leaking which is the weakness of any pump with a mechanical shaft from
motor/engine to pump impeller.

A fact that's taken advantage of by those cheap, no name, water cooled
'sealed for life' CPU heatsink kits used by some PC systems builders
where the CPU water block incorporates the circulator pump based on the
same magnetically coupled impeller design.

I know about these rather pretentious CPU 'cooling solutions' from a
recent experience with my daughters 'custom built' PC which she had lent
out to my son after it had been in storage for some 6 months or more in
our front parlour (the result of a house move and our willingness to save
her and the SiL the costs of storage whilst they were living in a rented
rabbit hutch when house hunting for a more permanent residence in the
locality).

After said son had spent a day setting this "Turbo-charged" desktop
tower PC up and downloading the latest updates for the latest of one of
the many first person shoot 'em up games (a Command and Conquer-a-like -
possibly even *that* very game) he started seeing the game slow down and
stutter within a matter of minutes of starting to play the game,
discovering that the cpu was throttling back due to excess temperature
(86 deg C Istr) which lead to my involvement in diagnosing the cpu
cooling setup.

Initial examination showed a spot of corrosion lifting the copper
plating off the cheap die cast or aluminium water block come circulator
pump which I thought may have been lifting the block away from full
contact with the cpu heat spreader. There was also some discolouration
suggesting a slow leakage of coolant, presumed to have been slow enough
to have evaporated away harmlessly.

undiscouraged by this, I dressed the spot of corrosion down with a fine
file and we reassembled it to test my remedial work. Needless to say, if
anything, it seemed slightly worse and I eventually realised that either
the pump impeller wasn't actually spinning or else the coolant had leaked
out. It turned out to be the latter, at which point we both decided
against wasting any more time trying to effect a bodge repair by trying
to recharge it with water when the initial leak may well have been
aggravated by the extremely high temperatures it had recently been
subjected to.

I opined to my son that a good quality traditionalfan cooled heatsink
would do an equally (if not more) effective job than that cheap no name
water cooling kit had managed at its peak of performance.

I don't think my son decided on this course of action until he realised
that he'd be spending silly money on fitting another expensive water
cooling kit on a computer that he was only borrowing and did not own.

A few days later, we took delivery of the fan cooled heatsink my son had
ordered from an Ebay trader and I was (once more) roped into fitting the
replacement heatsink assembly and, for a few hours afterwards, I was
treated to the thumps of explosions and various sounds of house to house
combat.

Taking time out to pop upstairs to his bedroom, I was able to witness a
very smooth high framerate rendition of the game in progress which was
all the proof I needed to confirm my opinion regarding a fan cooled
heatsink as being a more than sufficient alternative to the originally
fitted water cooling kit. :-)

I think the problem with this cheap water cooling option was the use of
crap materials and the combining of the pump impeller into the water
block itself in a "Sealed for Life", non-refillable cooling system
intended to be fitted by unskilled labour.

Quality water cooling systems (which require a higher level of
mechanical and plumbing skills than the average home computer enthusiast
would typically possess) use a seperate pump and simple water blocks
fabricated out of solid copper, generally coupled together with
transparent tubing which allows inspection for signs of low coolant level
or pumping problems.

However, as I recall, these are normally filled via the heat exchanger's
header tank which allows visual inspection of fluid level and, I'd
expect, obvious signs of coolant flow - the temperatures normally remain
well below boiling point and don't require to be sealed against pressure
build up as in the case of a car radiator - just sealed simply to reduce
evaporative losses.

The point to note with all of these liquid cooling systems, regardless
of quality and expense, is that magnetically coupled impeller designs are
used universally simply to eliminate reliance on shaft seals which will
eventually start leaking sooner or later - there'll be problems enough
with coolant leakage just with the static seals on pipework couplings
alone (but problems here are more readily dealt with and amenable to home
repair than in the case of a leaking shaft seal on a miniature 12 volt
brushless DC motor driven pump).

--
Johnny B Good

The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Well, yes, but the wires tend to be vulnerable.


A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water.

No, it just needs a step down transformer somewhere.

Most cheap submersible pumps are just mains, no step-down.

--
Chris Green
·

"Dave Plowman (News)" wrote:
In article ,
Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Wonder just how long a pump motor which wasn't waterproof would last when
left outside in all weather? Or were you going to build a special pumping
house for it?

I already have the 'pumping house'. Since a pond circulation system
usually needs such a housing for the external filter and the external
UV treatment a bit of extra space for a pump is neither here nor
there.

--
Chris Green
·

On Saturday, 6 August 2016 00:55:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Wonder just how long a pump motor which wasn't waterproof would last when
left outside in all weather? Or were you going to build a special pumping
house for it?

That's how some pumps are done. Having lived with a few I remember the priming was less than entirely reliable. Submersible garden fountain pumps are of course a cheap approach that works for baby sized pumps.


NT

On 05/08/2016 21:34, Rod Speed wrote:


"Fredxxx" wrote in message
...
On 05/08/2016 18:31, charles wrote:
In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket.

This thread was about motors running directly in water, with no
waterproof jacket.

Like hell it is. It is actually about submersible pumps.

No it was a follow on from the statement "I'm sure there are other
reasons too like not such an issue if the
casing halves leak".

wrote in message
...
On Saturday, 6 August 2016 00:55:48 UTC+1, Dave Plowman (News) wrote:
In article ,
Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Wonder just how long a pump motor which wasn't waterproof
would last when left outside in all weather? Or were you going
to build a special pumping house for it?

That's how some pumps are done. Having lived with a few I remember
the priming was less than entirely reliable. Submersible garden fountain
pumps are of course a cheap approach that works for baby sized pumps.

Not just baby sized pumps, works fine for massive great bore pumps too.

"Fredxxx" wrote in message
...
On 05/08/2016 21:34, Rod Speed wrote:


"Fredxxx" wrote in message
...
On 05/08/2016 18:31, charles wrote:
In article ,
Fredxxx wrote:
On 05/08/2016 18:08, The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Perhaps you could find an example where you'll find a motor that will
run whilst immersed in water. I haven't found one yet.

Pond pumps run underwater - enclosed in a waterproof jacket.

This thread was about motors running directly in water, with no
waterproof jacket.

Like hell it is. It is actually about submersible pumps.

No it was a follow on from the statement "I'm sure there are other reasons
too like not such an issue if the casing halves leak".

Even sillier than you usually manage.

In article ,
Chris Green wrote:
"Dave Plowman (News)" wrote:
In article ,
Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water. A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water. A pump outside
the pond doesn't have this requirement, all it needs is a shaft from
the 'electrical' end into the 'pump' end.

Wonder just how long a pump motor which wasn't waterproof would last
when left outside in all weather? Or were you going to build a special
pumping house for it?

I already have the 'pumping house'. Since a pond circulation system
usually needs such a housing for the external filter and the external
UV treatment a bit of extra space for a pump is neither here nor
there.

Right - I'm not a pond person. Is there not an all in one unit available
which does what you want?

And as I said before, you'd need two pumps (or two in one) if fitting
above the water level, as the common impeller type won't lift water very
far.

I recently replaced the socket for a pal's pump. It had been damaged when
fitting some decking. The submerged pump was still OK and is more than 20
years old. But not run 24/7.

--
*If we weren't meant to eat animals, why are they made of meat?

Dave Plowman London SW
To e-mail, change noise into sound.

On 06/08/16 09:58, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 17:48, Chris Green wrote:
The Natural Philosopher wrote:
On 05/08/16 14:44, www.GymRatZ.co.uk wrote:
On 28/07/2016 12:27, Chris Green wrote:
Why is it that pond pumps are always submersible ones?


The short answer is why wouldn't they be?

Because electrical things in general don't mix well with water.

electric motors run just fine underwater.

Well, yes, but the wires tend to be vulnerable.


yeah. I know. Sharks eat them


Simply doesn't happen with overhead cables left out in te rain.


A
submersible pump, especially a mains one, needs to have good, durable
separation of all its electrical bits from the water.

No, it just needs a step down transformer somewhere.

Most cheap submersible pumps are just mains, no step-down.


Then they use the other methodology. contactless mechanical couplings


--
"Anyone who believes that the laws of physics are mere social
conventions is invited to try transgressing those conventions from the
windows of my apartment. (I live on the twenty-first floor.) "

Alan Sokal

On Saturday, 6 August 2016 12:01:10 UTC+1, Dave Plowman (News) wrote:
In article ,

I already have the 'pumping house'. Since a pond circulation system
usually needs such a housing for the external filter and the external
UV treatment a bit of extra space for a pump is neither here nor
there.

Right - I'm not a pond person. Is there not an all in one unit available
which does what you want?

And as I said before, you'd need two pumps (or two in one) if fitting
above the water level, as the common impeller type won't lift water very
far.

the priming pump can be litle mroe than a bicycle pump. Our first one only needed priming occasionally.


NT