Transfer pump

[pool250]

Trying to pump out groundwater after heavy rain.
Have moved pump out of excavation above pool and attached quite a long suction side hose but now having probs.
Is there a limit as to the length of suction side hose and height of pump?. when hose was short and pump down in excavation, pump was working but I need to have the pump out of the pool area. Is this just a matter of insufficient priming water in the suction hose or too long a hose/too high a pump?
thanks

 

[bk406]

You have to look at the pump size. The insert that came with it should tell you what it will pull in terms of height.

 

[duraleigh]

too long a hose/too high a pump?

Almost surely that is the issue.

 

[pool250]

You have to look at the pump size. The insert that came with it should tell you what it will pull in terms of height.

It says 7 metres suction height max. I have an 11 metre hose on there but the actual height difference is only 1.5 metres.

What would be the max length of pipe (1.5") with a height of 1.5m?

 

[JasonLion]

It may be a question of getting the pump to prime correctly. If the suction hose starts out full of air the pump will have a very hard time getting going. If you can fill the suction hose with water, keep the suction end blocked off, lower the section end into the water at the bottom and then turn the pump on and release the seal on the pipe at about the same moment it might well get going from there.

 

[pool250]

I cut the pipe to the shortest length possible, primed with a hose and got the thing going.
Only problem now is when the water level drops, the hose gets air into it and pumps intermittently. Will fit a valve which will stop air getting in; the only trouble with that is it keeps getting blocked with twigs etc. Tried putting a sock etc over the end, but they kept getting blocked.
Fortunately I found there is a non return valve on the suction side of the pump so the prime water cant get out.

 

[pool250]

Appears its not air but the pump running faster than the water can get to it now that the level is quite low.
Fitted a valve on the out hose to restrict flow and put the pump on low revs: seems to have done the trick. Sweet spot between water flowing to
sump and pumping speed.