Electric suction pump to lift water 1metre.

[epsilonGreedy]

Can a small electric pump suck water up a 1m height differential?

 

I would not be looking for a stellar flow rate, just something slow and steady via a 1" or 1.5" hose. This is for a surface/flood water scenario though the water will be free of lumpy debris or sludge.

[Jeremy Harris]

Yes.  The limiting factor is air pressure, which limits the theoretical maximum head that a pump can suck to about 30ft, although in practice few pumps manage better than about half this on the suction side.  Priming is the only real issue, as a non-positive displacement pump (which many are) won't suck at all unless the suction pipe is full of water.

[epsilonGreedy]

24 minutes ago, JSHarris said:

Yes.  The limiting factor is air pressure, which limits the theoretical maximum head that a pump can suck to about 30ft

 

 

I can still remember my O level physics teacher rigging a clear water hose from the 4th floor teaching lab to illustrate atmospheric pressure.

 

24 minutes ago, JSHarris said:

although in practice few pumps manage better than about half this on the suction side.

 

 

That makes sense because to start the upwards draw of water, pressure must lowered even further than already caused by weight raised column of water.

 

24 minutes ago, JSHarris said:

Priming is the only real issue, as a non-positive displacement pump (which many are) won't suck at all unless the suction pipe is full of water.

 

 

This sounds like a gotcha because with the use I have in mind I will have to push a 1" hose down a 4" rigid access pipe until it reaches a flooded sump of water at the base of my block & beam floor void.

Edited August 27, 2019 by epsilonGreedy

[Temp]

Look for a self priming pump that can handle a negative head and dirty water.

Edited August 27, 2019 by Temp

[Ferdinand]

50 minutes ago, epsilonGreedy said:

 

I can still remember my O level physics teacher rigging a clear water hose from the 4th floor teaching lab to illustrate atmospheric pressure.

 

 

That makes sense because to start the upwards draw of water, pressure must lowered even further than already caused by weight raised column of water.

 

 

This sounds like a gotcha because with the use I have in mind I will have to push a 1" hose down a 4" rigid access pipe until it reaches a flooded sump of water at the base of my block & beam floor void.

 

 Thought you just topped up the exit pipe  with a jug of water from the top, or similar mechanism.

 

In this case do you not just need a side connection where you can connect a hose to initially fill the tube from the top, and an air valve at the very top to let the air out?

 

How precise it all needs to be will depend on how tolerant the whole thing is.

 

F

 

Edited August 27, 2019 by Ferdinand

[Temp]

Some pumps are specified for say 30 seconds dry running eg until they prime themselves. Main problem is when the water is all gone they burn up unless you are there to switch them off.

[Jeremy Harris]

Priming by pouring water down the outlet works OK if the pump has a foot valve on the end of the intake.  Easy enough to fit one, just needs a one-way valve on the intake strainer.  You can then fill the intake pipe up and prime the pump by pouring water down the outlet.

[Temp]

If this is just a one off use then something like this might do the job.

 

https://www.amazon.co.uk/Wolfcraft-2202000-Water-Pump-1-300/dp/B0001P1972?ref_=fsclp_pl_dp_9

 

Needs a drill to power it. Self priming with 3m lift. 

 

If it's going to be used more frequently you want something better controlled by a float valve perhaps.

 

Might also be able to hire one?

Edited August 27, 2019 by Temp

[Ferdinand]

Or there are narrow submersible pumps. But this may already be Plan B.

 

Or Plan C. Plan B may be @epsilonGreedy junior and a hose pipe.

 

Edited August 27, 2019 by Ferdinand

[epsilonGreedy]

36 minutes ago, Temp said:

Look for a self priming pump that can handle a negative head and dirty water.

 

 

I expect the water will be cleanish because I dug a sump in the under floor oversite, lined it with a layer of permeable material, then dropped in an underwater soakaway crate and then wrapped it over the top. There should be a 150 liter pool of filtered water to extract.

 

 

[epsilonGreedy]

34 minutes ago, JSHarris said:

Priming by pouring water down the outlet works OK if the pump has a foot valve on the end of the intake.  Easy enough to fit one, just needs a one-way valve on the intake strainer.  You can then fill the intake pipe up and prime the pump by pouring water down the outlet.

 

 

This sounds promising. I need to take care not to get the temporary hose permanently snagged at the bottom of the sump with extra bits attached at the end of the hose, for example the excess tail of a jubilee clip. There is also a 60 degree bend towards the end of the access pipe where it turns vertically downwards into the sump.

 

I hope a strainer is not required because the whole sump is wrapped in a permeable material to form a 150l strainer.

[epsilonGreedy]

31 minutes ago, Ferdinand said:

Or there are narrow submersible pumps. But this may already be Plan B.

 

Or Plan C. Plan B may be @epsilonGreedy junior and a hose pipe.

 

 

I am still trying to formulate plan A.

 

As it happened we had a summer deluge of 1" of rain the day after the floor blocks were laid but before the grouting sealed up the floor. This was enough to cause my sump to fill. I tested the access pipe by pushing a 1" flexible hose down the 4" pipe and was able to suck the pooled water up maybe 500mm but not draw it above ground level. At this point I realized I need to search for a pump that can deal with what I now know is a "negative head".

[epsilonGreedy]

1 hour ago, Temp said:

If this is just a one off use then something like this might do the job.

 

 

In the early days post build I might test the sump mid winter out of curiosity after that it will, I hope, be a once in 5 years type event.  

Edited August 27, 2019 by epsilonGreedy

[Jeremy Harris]

35 minutes ago, epsilonGreedy said:

 

This sounds promising. I need to take care not to get the temporary hose permanently snagged at the bottom of the sump with extra bits attached at the end of the hose, for example the excess tail of a jubilee clip. There is also a 60 degree bend towards the end of the access pipe where it turns vertically downwards into the sump.

 

I hope a strainer is not required because the whole sump is wrapped in a permeable material to form a 150l strainer.

 

 

I'd never use a jubilee clip for something that might fall off down an inaccessible hole, personally.  Easy enough to use an "O" clip,  more secure than a jubilee clip and a fair bit smaller.  You could probably get away with having the non-return valve part way along the suction hose, depending on how well the pump stays primed. 

 

I'd be inclined to use a strainer, if only because you can't be sure that something may not have gone down the hole and died, only to then get partially sucked into the intake pipe.

[ProDave]

We used to use a lift pump to draw water out of a well for watering the garden.  That pump had to be primed.  It had a non return foot valve incorporating a strainer.  Once primed it seemed reliable, but I am not sure I would want to trust that for a flood defence mechanism, as you don't want it to not work in a flood because it needs priming to start it.  I would just use a submirsible pump, you know that is going to start as long as it is sitting in water.

[epsilonGreedy]

13 minutes ago, ProDave said:

We used to use a lift pump to draw water out of a well for watering the garden.  That pump had to be primed.  It had a non return foot valve incorporating a strainer.  Once primed it seemed reliable

 

 

Good to hear.

 

13 minutes ago, ProDave said:

but I am not sure I would want to trust that for a flood defence mechanism, as you don't want it to not work in a flood because it needs priming to start it.  I would just use a submirsible pump, you know that is going to start as long as it is sitting in water.

 

 

The best location for the floor void sump was under the main sitting room 19ft x 17ft where I would not want a sealed manhole cover to access the sump pump, in fact can such an access point be created in a concrete beam suspended floor structure?

 

My hunch is that over multiple decades a simple 4" access pipe is more maintainable than a powered pump. Because the house is raised I actually ended up with a 400mm high space between beams and oversite subsoil which is almost enough for a crawl space, as a result there could a significant flood in the village and my floor beams would still be standing above any water pooled in the floor void. The main idea of the sump drainage pipe is to accelerate drying after the event.

Edited August 27, 2019 by epsilonGreedy

[Mr Punter]

How will the water get under the floor in the first place?

[andyscotland]

23 minutes ago, epsilonGreedy said:

The best location for the floor void sump was under the main sitting room 19ft x 17ft where I would not want a sealed manhole cover to access the sump pump, in fact can such an access point be created in a concrete beam suspended floor structure?

 

Couldn't you run a horizontal drain from the bottom of the soakaway crate to a sealed chamber outside the house and then use a standard submersible pump to pump that out?

 

That can then kick in automatically on a float switch, easy to maintain/replace, no need to prime, no issues with poking something down a pipe and hoping it comes back up etc?

 

I assume the geography of your site rules out just gravity draining the soakaway to run off away from the house, or to your main surface water disposal.

[scottishjohn]

3 hours ago, epsilonGreedy said:

Can a small electric pump suck water up a 1m height differential?

 

I would not be looking for a stellar flow rate, just something slow and steady via a 1" or 1.5" hose. This is for a surface/flood water scenario though the water will be free of lumpy debris or sludge.

 auto bilge pump

[epsilonGreedy]

8 minutes ago, Mr Punter said:

How will the water get under the floor in the first place?

 

 

1. Surface water pooling in heavy periods of rain around the site that then finds its way through the soil to the void.
2. Ponding risk in one part of my site that can reach back to the original foundation trenches where the water can then wriggle through the footing blockwork into the void.
3. Exceptional 1 in 30 year surface flash flood risk that could lead to a flow of water across the site and around the foundation walls below dpc.