Run submerged waterfall pump without water, what will happen

[herbolaryo]

In the manual of the submerged waterfall pump...
It says, don't run motor without water.
If the motor run without water, what will happen to the pump?

 

[Steve]

booom!

 

[breezer]

try it and let us all know

seriously it depends on the pump.

either way it will heat up.

a good pump will have a thermal cut out in it and stop it.
if you have a constant pond leak, fix it, or buy a float switch

 

[herbolaryo]

I asked this because sometimes there are blackout of electricity and it drains all the water out. And when electricity comes back at the unholy hour of the night, the motor may run without water.


If this happens to the motor ,What can happen to the motor?

Can the motor be repaired?

 

[kevindgas]

best to reposition pump lower down so it self primes / doesn't lose water during power cuts
mine is 6" lower than the water level of the pond and never dries out (mind you it is a 15/50 circulating pump) last about 3 years then i wack another one in

 

[herbolaryo]

best to reposition pump lower down so it self primes / doesn't lose water during power cuts
mine is 6" lower than the water level of the pond and never dries out (mind you it is a 15/50 circulating pump) last about 3 years then i wack another one in

It is positioned at the lowest possible. however during initial refill when electricity comes back, the water pouring IN to the pump does not match the suction of the pump. Making it suck some air.

 

[kevindgas]

wouldn't a bigger inlet than outlet solve that?

 

[breezer]

a drawing may help to expalin your situation.

inserting picture info is in forum information

why cant you move the pump (see what i mean about a drawing) or as il also said fit a float switch

 

[nozspark]

Had a problem with a customers MCB that kept tripping, ended up that his pond / waterfall pump was running dry......

The only issue then was talking said customer into filling his pond a bit more and leaving the pumps running 24/7 so as to keep top pond/stream/bottom pond full.

 

[breezer]

hows that work then? (the lay out not why the mcb trips)

a stream runs from the top, so pump should be in the bottom or sump so it can pump to the top

even if it was a stream the pump should be at the bottom

 

[nozspark]

The stream was only about 1/5 mtr wide and 15 mtrs long.

Pump was in bottom pond, when you switch pumps on it obviously pumps water into top pond. Before the water completed the loop the pump was running dry as the owner thought that he could have it on as and when it pleased him. Ended up that the whole pond system needed a good bit more water to run properly..

 

[breezer]

ah, i see, his sump was too small (i over looked the obvious)

 

[nozspark]

I don't think that his sump was too small, I think (didn't check) that it isn't using a submerged pump and that the inlet pipe was not deep enough or damaged and hence only allowing about 1 inch of drop in the water level before it ran dry. (also found that a UV filter was faulty)

As I'm not an expert with ponds and their filtration I told him to get an expert in as I did not want to responsible for the death of his carp/goldfish..

 

[herbolaryo]

The pump is located downstream the falls with a float switch to top off the water when it gets low due to normal evaporation of water.
However, there are unexpected electricity blackout which empties the whole pond. Since the float switch can not keep up , during the time when electricity just came back, it sucks up air.

The pump sucking air only happen during occassional electricity blackout.

The humming noise occurred after that time eventhough I cleaned the filters and the motor "blade" of debri.

So what can be the cause of the hum noise in the pump and how to fix that?

 

[breezer]

I would guess pump is on its way out
probablyits bearings are wearing

float switch should be in the sump not at the top

any chance of some pics

picture posting info is in "forum information"