Pumped Well Enquiry...

Hi All,

For my sins I now live in Ireland and have to wire up my sisters new well system.

Being a newbie on this sort of job, I need some advice.

The pump is 64m down the bore-hole, which is 200m from the house. The pump feeds into an adjustable pressure vessel and then to filters etc.

At present the pressure vessel is at the top of the bore-hole. However, I would prefer to move the vessel to the house which is 20 m above the bore-hole as well as 200m away.

So now to the questions...

1 hydraulically speaking, will the pressure vessel work up at the house.

2 it has two adjustments inside which i think are a cut out and cut in. Does anyone know how to set it up?

Cheers

Alan

I've done several like this.

At present, with the pressure vessel 20 M below the house, then the water pressure you actually get out of the taps will be lower than the pressure in the vessel.

Moving the vessel close to the house means you won't get a reduction in pressure, so you will need to reduce the set pressure of the pressure switch. Usually there are two adjustments, switch off pressure, and hysteresis. The hysteresis setting should not need adjusting, just reduce the switch off pressure to what you want to come out of the taps.

A few more points to make the system safe (based on my finding a very unsafe system installed on a farm near me)

Do make sure the expansion vessel is regularly serviced. That means checking the pressure in the air bladder.

Do make sure there is an over pressure blow off valve and this is checked regularly. I was horrified to find the one on the farm near me had no over pressure blow off, and a stuck relay switching the pump had led to the tank pressurising to 13 bar, well beyond it's 10 bar rating. It's a wonder nothing went horribly wrong with that one.

As Dave says you shouldn't need to adjust the hysteresis (sometimes called the differential) which is the thinner of the two springs so only adjust the nut on the thick spring to achieve a decent tap pressure and make sure that the pump switches off when no water is being drawn.

whats wrong with some of this



and this

Cheers guys....

So I can move the pressure vessel up to the house then....

When I put my thumb over the pipe, it tripped the vessel switch. Adjustment down there does not seem to do much as the pressure is 50 lbs with the pipe open at the house. That must be the weight of the water down the hill then..

As an aside, the well pump is marked at 0.37kw and appears to be fit for the job... It fills a 10 litre bucket in 45 seconds. The only worrying thing is that I checked the running current and it comes in at 2.8 amps. I don't know the power factor but am sure some of the amps is 'slop'

I said to my sis we will play it by ear and if the pump croaks we will get something a bit more powerful....

Think about it. the pump MUST have enough pressure, as it pumps the tank up to a high enough pressure for it to reach the house.

when you move the tank higher, the pressure the pump can generate will be lower, but so will the pressure needed in the tank to give the correct working pressure in the house.

0.37KW sounds like a small borehole pump. It will probably specify it's maximum head somewhere as well.

Success! Well i think so!

I have took the pressure vessel and moved it up to the house...which is about 85 m above the submerged pump and 25m above the surface of the well water.

As I said, when the pipe was full and the vessel was down at the well head we had 45lbs/in. I have set the house sited vessel to cut off at 45 lbs/in so there will be about 90lbs at the well head. The differential cuts in at 25 lbs/in so happy days. The overload tripped out a couple of times so I turned the o/l up to its 4A maximum. It is still drawing about 2.8- 3A by the way, which is a little high, not withstanding the unknown power factor.

As my sister says, we have no choice. If it smokes the pump, we will replace the thing with something bigger. Me? I have a funny feeling it will live on due to the fact is is submerged....

Best wishes

Alan

Hi Pro Dave,

The pump was marked with 'H- 27-72m' Was that the head maximum and if so, why two?

Alan

Doc, where abouts did you actually move to?

Im just nosey, if you prefer not to say, no worries.

the doctor said:

Success! Well i think so!

I have took the pressure vessel and moved it up to the house...which is about 85 m above the submerged pump and 25m above the surface of the well water.

As I said, when the pipe was full and the vessel was down at the well head we had 45lbs/in. I have set the house sited vessel to cut off at 45 lbs/in so there will be about 90lbs at the well head. The differential cuts in at 25 lbs/in so happy days. The overload tripped out a couple of times so I turned the o/l up to its 4A maximum. It is still drawing about 2.8- 3A by the way, which is a little high, not withstanding the unknown power factor.

As my sister says, we have no choice. If it smokes the pump, we will replace the thing with something bigger. Me? I have a funny feeling it will live on due to the fact is is submerged....

Best wishes

Alan

Click to expand...

Glad to hear it's working. The head of your system may be a little higher than the 72 meters it's designed to pump so this may shorten its life span. The other thing that causes failure is short on/off cycling times (especially with single phase pumps) but if your reservoir tank is big enough and the internal bladder is fine then it shouldn't be a problem. If at some stage you do replace the pump maybe look at getting one that's capable of 100m max head.

Marvo said:

Glad to hear it's working. The head of your system may be a little higher than the 72 meters it's designed to pump so this may shorten its life span. The other thing that causes failure is short on/off cycling times (especially with single phase pumps) but if your reservoir tank is big enough and the internal bladder is fine then it shouldn't be a problem. If at some stage you do replace the pump maybe look at getting one that's capable of 100m max head.

Click to expand...

I read it as the head was 25 metres and the 85 metres was the horizontal distance. If so the pump will be fine. If it really is 110M total head, then I agree the pump will be struggling.

hi All....

Thanks for the replies...

Where am I? In a little town in County Monaghan called Newbliss but have an offer in for a house in a slightly bigger town called Belturbet in County Cavan..

right- the numbers!

The well is 69m deep but the water is 5m down so the water is 64m deep. We have the pump at 4m from the bottom so there is 60m of water on top of it. The house is about 20m higher again but 200m to walk. That makes the head about 25m then?

Having walked up that hill enough times I sympathise with the little pump and the work it does. I wish I had taken a current reading, when we ran it in a barrel in the front street.... The current is high in my opinion

The flow figure? I wish I had noted all the numbers, but it appears to be able to pump a cubic metre in about 75 minutes.... quite amazing. Even more amazing is that you cant hold your thumb over the end when it pumping. You stop the water for a couple of seconds then it starts to blow your thumb off!

Alan

I think I might have misunderstood the arrangement you have. Now you've explained it I'm even more confused I'm afraid but English is only my second language so maybe that's also part of the problem.

So you have a well that's 69m deep but the water level in the well is only 5 meters down from the top of the well.

If I'm right so far, why don't you pump the water with a standard jet type centrifugal pump on the surface? A standard surface pump can self prime if it's less than 9m above the water level. With some minor modifications a centrif surface pump can even work if it's 16-17ish meters above water level. Why is the existing pump 64 meters below ground level and 59 meters under the water level?

With the arrangement you have is not easy to calculate the head pressure the pump is working under, it won't necessarily be only 0.5 Bar to ground level plus another 2 Bar to the house height plus pipework losses. There is a good chance however that the pump is running very much under it's minimum required head pressure as per your figures in a previous post which means premature impellor damage may occur. Lack of head pressure could also be causing a higher than normal running current.

Edit,In your opening post you said you had a borehole....which you're now calling a well. Pleas can you describe exactly what the hole in the ground looks like and how it was made?