Thread: water pumping problem

Does this need to be a pressure sensitive pump, ie it switches on when a tap is opened or is this a transfer pump, only switched on when needed?

If it only needs to pump when switched on, then a submersible pump would do the trick.

I have 2 of these in my septic system and they are switched on by a controller. One pumps out the cleaned water through the sprinkler system, one gets switched on at regular intervals to aerate the sewage water.

They acn be expensive, ie the Davey for recirculation cost me $450 to replace, but Aldi has one on sale atm with identical specs for $79 (bought one as a spare at that price!).

If it needs to be pressure sensitive I don't know how that works as my pressure pump is at the bottom outside of my water tanks and has a 2.4mtr head.

This may be seem like a silly question, but are you sure the pickup pipe is actually submerged under water? Also are you sure that the check valve (non return valve) is working (i.e. not blocked, hence not allowing water into the pickup).
The reason I ask is that:

1. You can prime the pickup with water, which I assume doesn't run out anywhere i.e. the check valve must be working (at least in one direction) as the pickup stays primed.

2. You can turn the pump on and the prime water is pumped, but then nothing. I would assume from this that the pump can lift all the water in the pickup and then either create a vacuum ... or it's sucking air through the the check valve.

One other thing that came to mind ... is the end of the check valve/pickup pushed against the bottom of the tank, stopping water being drawn up?

What about putting food colouring in with the prime water, that way you can check if it actually getting anything from the tank as well?

Other issue to cosider is the suction (lift) rating of the pump. They normally have a suction or lift rating, and a head rating. Suction or lift is the distance that they can lift water from tank water level to pump, head is the distance they can push water from the pump to the end use.

If the lift rating is inadequate, the pump will not suck water from the tank to its inlet.

The other consideration is to keep the suction line as short as possible and avoid any above ground changes of level as these can help create airlocks.

Gosh you chaps are really on the ball , I have only just posted the question
Now I have had this working in the past before I put in the T piece for the priming. Not sure though how I did it. I already have the pump so although the submersible is an option the pump I have will have to do as its almost new. I did check the one way valve, seems OK even took it off to test, I had to have pressure fittings as the flow is so strong, that's another problem, how to reduce the pressure.
Fortuneately this water is only for the garden and does not need to work when the tap is turned on but only when the pump switch is turned on.
O well will keep trying
thanks to all
Robert

PS the blocking of the pipe may be the problem, there is a filter on the end though.

Can you please send us a diagram of the entire system, showing how it is actually connected? Please show the valves and filters, everything, including relative heights to ground level.

That may clarify the situation

regards,
Jill

the hose you fitted to prime is not at the top. you need to make sure the pump is full of water - if there is no valve where the pick-up attaches to the pump then the hose into the tank cannot have any air in it either.

the best place for your priming hose would be the highest point on the pipe to allow air to escape as you fill with water. at the moment you have water in the tank section, water from the bleed hose to the pump and air from the bleed hose to the top of the tank then inside the tank for the same distance, you need to get rid of this air.

The height the pump is "lifting" the water is from the water level in the tank to the pump height. The distance the pipe is below the water surface and up over the tank edge down to the pump is irrelevant but you cannot have any air in this section at all.

Get rid of the air and the pump will pump the water.

Another look at the photo and it may be sideways if that is the case then i think your joins are possibly allowing the pump to suck air

Cheers

Hey There,

This might be a dumb question, Is there Water in the tank??

Question # 2 Has the System been Working and then Modified?? if so Take out the Modification and see if it still works, if not, then the Impellor in the pump might have some shyt in it, those little pumps have a Centrafugal impellor and even a couple of blades of grass can make them not work. Just adding my two bobs worth.

HazzaB

Attachment 121470

Hi Mr Calm
Thanks for the reply just needs a little explaining for this dumb cove.
Attached is rough sketch of configuration, if you could modify the drawing showing what it should be, I would be ever so grateful

thanks
Robert

Thanks Jill for your interest, attached is a very rough sketch of the setup, suggestions would be most welcome

thanks
Robert


QUOTE=JillB;1060318]Can you please send us a diagram of the entire system, showing how it is actually connected? Please show the valves and filters, everything, including relative heights to ground level.

That may clarify the situation

regards,
Jill[/QUOTE]

I'm no plumber (that probably explains why I'm poor!) but I would guess that the length of primer pipe is your problem.

Once you fill it with water and prime the system, the pump starts working and promptly sucks the water out of there and if there is even the tiniest air leak it will suck air.

I would either remove the primer pipe and T piece altogether, or failing that have the shortest pipe possible.

On my fire pump at the dam, I prime the Honda fire pump on the pressure side (ie outlet) and have a valve for that so I can close the system as soon as it is primed and pumping.

Here i have rotated the picture and it is now the same as the drawing above.

Attachment 121478

Check there is not a "rubber flap" on the outlet of the pump - over winter these can stick shut.

fill the pipe with water using your new primer pipe - it should fill to the top and remain full if it is going down then the is a leak somewhere or the "foot valve" is not holding.

Turn the pump on let it run for a considerable time - put hand on pump to check it is not getting hot - allow the water to pump away and give pump time to suck up the water from the tank. Maybe 5 minutes.

How far below the pump is the water level in the tank?? (height pump is trying to lift) if this is more than 1.5 metres a small pump like that may struggle "first up"

All joins need to be tight and sealed on the suction side - any little bit of air will stop it working. - the pump cavatates and pumps nothing.

Hope that helps

Originally Posted by Calm

The height the pump is "lifting" the water is from the water level in the tank to the pump height. The distance the pipe is below the water surface and up over the tank edge down to the pump is irrelevant but you cannot have any air in this section at all.

I raised the issue of lift height and rating in my first reply. While Calm's comment about lift is correct, the actual water level is dynamic (i.e varies as water is added to or drawn from the tank), ultimately the pump has to able to draw the full height of the suction line to obtain maximum utilisation of the water stored in the tank. This was reflected in my original comment.

Originally Posted by malb

I raised the issue of lift height and rating in my first reply. While Calm's comment about lift is correct, the actual water level is dynamic (i.e varies as water is added to or drawn from the tank), ultimately the pump has to able to draw the full height of the suction line to obtain maximum utilisation of the water stored in the tank. This was reflected in my original comment.

You are right but to get the pump to pump now you only need to worry about the present water level, That is where the pump is presently NOT pumping from.

Cheers