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Author Topic: Which pump to use? RWH  (Read 5153 times)
taliz
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« on: January 06, 2017, 04:42:27 PM »

We have a allotment that has no mains water on at present, but we have just built a retention pond at the fields lowest point collecting groundwater.
Since Early November we have had a steady trickle into it of about 2000litres per day. The pond holds around 6000litres.

We would like a way of pumping the water to tanks on the highest part of the field so we can gravity feed to areas around the site. The top of the tanks are 7m above the water level in the pond and vertically around 70m away.

However, we have no mains power on site either so is there a 24v submersible pump we could run on solar that would be powerful enough? We would not need a fast flow rate as the pond doesn't fill up quick.

Alternatively, should we look at getting a generator to manually switch on a 240v pump when the tanks are low?

Any help is appreciated as i'm a little out of my depth.

\Thanks
« Last Edit: January 06, 2017, 04:43:59 PM by taliz » Logged
offthegridandy
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« Reply #1 on: January 06, 2017, 06:07:23 PM »

Sureflow make a range of 12 volt electric pumps for water systems in caravans.The pipe connectors are 1/2 inch like garden hose. I use one, solar powered for a pumped pond system, the filter being an old coke bottle punched with holes and an old tight over it.  I have an old car battery and a small pv panel connected straight on the battery.  If the sun shines the battery gets charged and then the pump runs.  When the battery is flat and the suns gone it stops.  Very cruel to a quality battery as it gets drained flat but as my battery is scrap I don't care.  A small investment could improve on this set up.  You'd  have to check out the pumps spec but I'm sure  it can cope with a lift of 7 meters.

Pump pressure is nominaly 100PSI.

Easy and cheap and very little for anyone to nick.

Cheerrs.

Andy
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taliz
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« Reply #2 on: January 07, 2017, 05:47:09 PM »

I have just looked at the Sureflo range, they are not submersible so I take it you would simply hang the hose into the pond with some sort of mesh on the end? I can't see a head or rise value in any specs.

Also, just seen this on amazon,
https://www.amazon.co.uk/gp/product/B01M2X7WZI/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=A2B9S5X73ZYYBZ
which seems to fit the bill.  I would peg a float switch in the pond so when the water dropped below a certain level the pump would stop. Would I also put one in the water tank to stop the pump or could i simply fit a ball cock?
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dhaslam
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« Reply #3 on: January 08, 2017, 11:40:02 AM »

If you want to leave the pump in position  a submersible pump would be less conspicuous.  You would need to have a good pump to  move any kind of volume at 7 metres head and  these pumps tend to use hundreds of watts.  If you are using an inverter it needs to have several times the capacity as well as suitable batteries plus solar panels,   The panels can be small  because they  will collect sun over  a long period and you only need to water in sunny conditions.       The panels would be very prone to being stolen or vandalised.     

It might be better just to use a petrol  powered  pump, even small ones have outputs equivalent to  electric pumps of several kilowatts  and would top up  the tanks in  a short time.  You could just take it with you when you go.   
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taliz
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« Reply #4 on: January 11, 2017, 08:23:06 AM »

Hi

Thanks for that, I hadn't considered a petrol pump. However, it seems to be the most viable option. Honda do a small hand held one that would suffice.

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oliver90owner
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« Reply #5 on: January 11, 2017, 09:47:32 AM »

Since Early November we have had a steady trickle into it of about 2000litres per day. 

One question might be 'What will the flow be in June-September?'  Might even dry up completely?

To raise 2000 litres by 7m  requires only 140kJoules.  Not really a lot of power when you consider one kilowatt hour is 3.6MJ (~25 times more). The 70m will have pipe losses dependent on bore, bends, etc.

A 25W positive displacement pump would shift that amount in less than 6 hours (requiring less than 1/3rd efficiency), I would think, provided the system was efficiently set up.  But that would need a clean water feed.

Other questions might be whether you wish to empty the pond once every 3 days or to take 2000l each day.

I have a less than one horse power petrol engined pump that should shift 2000 litres in about 30-40 minutes (its spec is 140l/minute and a max lift of 36 metres).  It weighs about 7kg fuelled up and self primes.  I've not tried it yet but I am hoping it will handle river water at about 100 litres/minute for about a 4-5m lift and 80 metre run for my garden using lay flat delivery hose.
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taliz
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« Reply #6 on: January 13, 2017, 11:17:26 AM »

The plan now is to get a Honda BE BW115HR petrol water pump and to initially fill the tanks over a few days or so and then just to keep topping them up as they run down.

You're right the water may dry up in summer. We'll have to wait and see. We may buy another 6 IBC tanks which would give us an 18000 litre reservoir (incl. the pond). Hopefully that would give us sufficient to see us over any drought.  It's difficult to judge, as it's a brand new allotment site we have no idea what our usage will be over summer.
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oliver90owner
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« Reply #7 on: January 13, 2017, 01:08:56 PM »

You will have a PM, shortly.

RAB
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