Assumed Low Water Supply In Borehole

[doglover]

I currently have a small project to carry out on my Mitsu WP-355Q house pump but I would like to start the info gathering process on my bore pump and borehole issues in the meantime. The local village borehole driller uses 2" PVC casing for the boreholes he drills. I have had him drill three boreholes for me. He will no longer come to my house to address any concerns as he seems to think I complain to much about the issues with these boreholes. He is the only local that has any knowledge of pumps (which is very little as he pulled the 'toss the spring from the check valve" stunt on my mitsu house pump)

.

1. In my old house. Lots of water available but always alot of coarse sand coming up with clear water.

2.My present house. Lots of water available but water always has a reddish tinge (appears to be from the red soil in the area) and is unusable for the house. It has since been abandoned as I now water the garden, lawn, etc. from a dugout via a submersable pump.

3.My present house and the borehole I am requesting info on has clear water but it is in short supply (so much for third times a charm!)

Or is it short supply?.... Originally, I ignorantly had my Mitsu WP-355Q pumping directly from borehole to house and garden. I noticed there was not as much flow as from the other boreholes but I was just happy to have clean water. I do believe this 3rd borehole is a few metres deeper than other two and am guessing it to be 11 - 13 metres. So maybe this was the cause. However the 3/4" pvc was used inside of the casing feeding the pump from the hole and I believe it was around 9 metres long. Apologies for the guessing but I would rather not pull out the pvc and gather solid figure, but I will if required. The were some issues with the pump (can't remember what) when I was away for a couple months working. My wife had the 'toss the check valve spring expert' out to solve the problem and he accordingly chucked the spring from the pumps check valve! When I returned home there was pump chugging issues with the water supply which also was forcing dark green algae flakes off the inside of the pvc pipes (my guess as to where it came from). I'm amazed at what Thais can live with minimal complaints.

(I was still clueless about water pumps at the time and now that I am starting the clue in process I can see that the missing spring from the check valve could be the culprit as I would imagine the check valve would still close but not as rapidly with the spring installed. But there was a different type of check valve at the bottom of the pvc in the borehole. A good quality one from brass with accompanying brass screen filter. So was it the pump losing prime? I cannot know for sure as I have since changed the setup.)

I informed a local hardware shop of my thought to be low water supply issue and he recommended the pump in the picture below because of the head required and desire to bring the water up at a slow rate to try to not pump the borehole empty. I now pump from the borehole via this basic EMA Super pump to a water storage tank and then from there to the house with my Mitsu WP-355Q. There are two issues I want to correct on the borehole end from the storage tank.

ISSUE #1 There is still a shortage of water volume being pumped from the borehole to the tank. My neighbour is using the same pump as me except he is using a generic 1/4hp motor and I am using a Mitsubishi 1/3 hp. He gets alot more water than me! I was assured I could pump from the depth I am by the hardware store owner who seemed knowledgeable. I fiddled with different lengths of 3/4" pvc feeding this pump and ended up with a length of about 7 metres providing the highest flow rate (originally went with a 10 metre length assuming a lack water supply in the borehole but the pump didn't have enough head). When the pump initially kicks on via the float switch there is nice full volum stream for about 3 seconds which is always followed by 50% reduction in flow that ebbs and flows somewhat (I believe this to be caused by that lack of any backpressure as the pvc enters near the top of the tank and the water simply falls in and not a pump chugging sort of issue)

ISSUE #2 The motor itself is hand stinging hot! Kudos to the motor as it has been running like this for awhile (about 7 months). The electrical connections are sound (in leau of me scabbing them in temporarily - i'm a procrastinator by nature). But now that my memory is coming to life... There was also an issue with metal on metal scraping between some of the parts of the arm that goes back and forth creating the pumping action. The pump has been filled with oil as required. So this may be the cause of the hot motor (which is not in direct sunshine) yet the metal scraping is not so severe as to impede the pumping action of the pump......so that leads me full circle to the low water supply again...

This is why I just threw my hands up some time ago before I was aware of this forum. I was just gonna run 'er till she burns! But now that there is help available.....

Edited January 26, 2011 by doglover

[gotlost]

You may want to check out this thread and have your post moved to this forum.

http://www.thaivisa.com/forum/topic/81390-boreholes/

[StasD]

I use 20 meters borehole and small pump which i brought from Russia. It is put to the bottom of the borehole and that is all. 2 months i got bad dirty water, it was working 24 hours but now everything is ok and I can drink water immediately, do not need to prepare of filter. I checked water in lab but not here, in Russia too

[kokesaat]

We had a number of problems with our well a few years ago....maybe something we did can help you isolate your problem:

No water: check valve remained open because of sediment. We replaced check valve but had same problem. We had someone come and 'blow out' the bottom of the bore hole. Problem solved. Cost was a few thousand baht (much less than 5)

A few years later, no water again: Tiny sediment again clogged the valve. Replaced valve, but new valve clogged soon after. I checked the level of the hole using a thin fishing line with a ping pong ball and light weight attached. When the ball no longer went down, I knew I reached the top of the water. Then I removed the ping pong ball and attached a slightly heavier weight. When it stopped, I knew I reached the bottom of the water. The water in the well is about 4 meters deep, year round. The checkvalve was nearly at the bottom. We clipped off about 3/4 of a meter of pvc, put everything back together, and the problem has been solved for several years now (knocking on wood).

Hope something in here helps you with your problem.

[Artisi]

Think you have more than 2 issues here.

1. why is the pump getting hot? if it's not pumping at full capacity and it has the correct size motor then it shouldn't be running hot unless there is some mechanical fault or the voltage drop to the motor is excessive, is the gearbox overfilled?

2. You need to establish where the water table is when not pumping and again when you are pumping on the well.

3. Your pump is probably only capable of something like 6 to 8 meteres of vertical lift including any losses in the pipework.

4. I would think that a well of this depth is only seeing surface water which has drained downwards so seeing "red-stained" water is not unexpected, plus its hygenic value would be very suspect.

5. with 7 metres of pvc it sounds as if the well is being pumped down to this level and then entaining air whereas when you have a 10 metres it is still immersed in water, the suction lift capabilities are exceeded and a vacuum or partial vacuum is being pulled on the pipe and the flow rate is diminished if not stopped altogether.

Enough to keep you busy for a day or two - once you sort these points out we can look further if there is still any problem.

[Pib]

Yea, you don't want to use the WP-355 for suction from a well as its suction lift capability is only around 9 meters and you seem to be saying your well is deeper than 9 meters. And actually this limited suction lift applies to pretty much all Mitsubishi, Hitachi, Fujika type pumps which are based on the general household design as their suction lift capability is in the 7 to 10 meter range only....they are designed/geared for pumping from above or below ground storage tanks, or water mains; not from wells. You really need a signal or dual jet pump or submersible design pumping system which are geared to wells. Mitsubishi, Hitachi, Fujika, and numerous other manufacturers also have pumps designed for wells. See this web site for more general info about well pumps. http://www.inspectapedia.com/water/Pump_Life.htm

[sezze]

This is correct . Your NPSH or minimal suction pressure is probably too low . The pump is self priming but if you are pushing it to its limits then you will not get any pressure on the pressure side .

2nd , your EMA pump is scraping you say . I guess this pump isn't new or is it ? Check the water and pump for sand or other hard impurities . Is your pipe going down filtered by any way ( small particle filter , used for any suction of sand inside the housing of the pump . Scraping sounds are not good and are definatly seriously damaging the pump . Rinse the pump with clean water . Is it still scraping , get your hands on some technical work . to find out where it is scraping . Is it the arm or is it inside the pump .

[doglover]

We had a number of problems with our well a few years ago....maybe something we did can help you isolate your problem:

No water: check valve remained open because of sediment. We replaced check valve but had same problem. We had someone come and 'blow out' the bottom of the bore hole. Problem solved. Cost was a few thousand baht (much less than 5)

A few years later, no water again: Tiny sediment again clogged the valve. Replaced valve, but new valve clogged soon after. I checked the level of the hole using a thin fishing line with a ping pong ball and light weight attached. When the ball no longer went down, I knew I reached the top of the water. Then I removed the ping pong ball and attached a slightly heavier weight. When it stopped, I knew I reached the bottom of the water. The water in the well is about 4 meters deep, year round. The checkvalve was nearly at the bottom. We clipped off about 3/4 of a meter of pvc, put everything back together, and the problem has been solved for several years now (knocking on wood).

Hope something in here helps you with your problem.

Yes that does help. Have never heard of "blowing out" the bottom of the borehole so that is good to become aware of that possibility. And checking the water levels as you mentioned is what I had in mind. I was just being lazy and hoping one of the resident experts would just hand me the answer from the info in my long winded opening post.

As another poster suggested. Checking the water level in the bore while pump is running would also answer the question as to wether or not the water level in the bore can keep up to amount being pumped out.

And thanks for the link Pib. I will check it out.

The other posters link to the borehole thread is an awesome ongoing read. Thanks all.

[doglover]

Update.... At present time it is not a low water supply issue. I should have just got off my butt before and checked the water levels. With the pump having been off for a few hours the water was high in the bore at 2M below gnd lvl. The foot valve of the 3\4" pvc riser is 7 M down. I could not get past this point with my potato peeler on a string to check the bore depth but my memory says it is 13M. When I turned on the bore pump the water level slowly dropped and stabilized just past 4M down. After turning off the pump and waiting 5 minutes the water level made it back up to 2.4M. I wish I would have checked this before the rice paddies were flooded a few weeks back. Would have been interesting to see the levels with the surrounding land dry.

My pump is still underperforming with a weak flow rate and the motor running hot after only 5 minutes in use. The metal on metal grinding has ground itself clear so there is no resistance there anymore. This was on an external pump arm and not sand or any other debris inside the pump. The pumps oil level is topped up. Tomorrow I will check the voltage while in operation. So this is ongoing, just wanted to mention that the water level in the borehole is plentiful and not guilty as charged.

[sezze]

Since this is a cilinder pump and not a centrifugal one then there is something you can check . Iside the pump there is a valve for pressure side and 1 for suction side of the pump . On these kind of pumps i recon this is just a ball thing which falls back in its fitting and thus closing the water flowing back to the wrong side . Is it possible to test these 2 , or at least inspect them . If by any chance the pressure side valve is not working correct ( as not opening completely , due to failure or dirt ) then this pump still wants to pump but cannot . This is resulting in overpowering the motor/pump ( your high temp on the motor and the scraping sound of the motor pressing on the cilinder to get it away ) . If it is the valve on the suction side , i expect a very low pressure but not really a high temp of motor .

[doglover]

Since this is a cilinder pump and not a centrifugal one then there is something you can check . Iside the pump there is a valve for pressure side and 1 for suction side of the pump . On these kind of pumps i recon this is just a ball thing which falls back in its fitting and thus closing the water flowing back to the wrong side . Is it possible to test these 2 , or at least inspect them . If by any chance the pressure side valve is not working correct ( as not opening completely , due to failure or dirt ) then this pump still wants to pump but cannot . This is resulting in overpowering the motor/pump ( your high temp on the motor and the scraping sound of the motor pressing on the cilinder to get it away ) . If it is the valve on the suction side , i expect a very low pressure but not really a high temp of motor .

Good call sezze. Pulled the pump and started to dismantle. There are two check valves on the pressure side and 2 more on the suction side. They consist of a rubber disc under an aluminum ring and held in place by a spring. One of the springs on the suction side was broken in the middle and all the parts were at the bottom floor at the far end of the cylinder. I thought this would be the source of the knocking but it still exists and sounds to be on the oiled side of the pump. So this should be the issue with the poor flow being that with one check valve dislodged only one half of the cylinder stroke would be operating properly..........or so I thought. After re-installing the pump I flicked the switch on in anticipation expecting a blast of water... only to see the same weak flow. Right from the beginning as well, there is no period of pressure followed by the weak flow. Even with 5 metres of static head water in the 2" casing. So it is not from a lack of well water and also not from pumping up from too far of a depth as the bottom of the drop pipe is only down 7 metres.

Something I noticed yesterday before pulling the pump is there are alot of air bubbles mixed in with this weak flow. The exact same scenario after replacing the check valve spring as well. This is not coming from a leak in the drop pipe above the static head either. With the installed pump sitting idle for a couple hours I removed the cap on black fitting at the top of the drop pipe used for priming and zero water loss. Any ideas anyone?

[hawaiiman]

Sounds like you've uncovered the problem. So it's gotta be sucking air at or past the priming point. Vacuum leaks are far harder to find than pressure leaks. I have no idea why pvc sold in Thailand seems to have all strait thread rather than pipe thread, but it's real hard to seal where the pipe fitting screws into the pump. I tried piling up a lot of tef. tape as the Thais do, but limited success. I finally solved it by just coating the outside of the suspect fittings with a heavy coating of pvc glue. Ugly..but it worked! chok dee

[doglover]

Sounds like you've uncovered the problem. So it's gotta be sucking air at or past the priming point. Vacuum leaks are far harder to find than pressure leaks. I have no idea why pvc sold in Thailand seems to have all strait thread rather than pipe thread, but it's real hard to seal where the pipe fitting screws into the pump. I tried piling up a lot of tef. tape as the Thais do, but limited success. I finally solved it by just coating the outside of the suspect fittings with a heavy coating of pvc glue. Ugly..but it worked! chok dee

Sezze helped me to uncover part of the problem. Something interesting (and frustrating) about what I found after post #11 that I did not report.... After replacing a new spring for the check valve that had worked itself loose and re-installing the check valve as I had mentioned the flow was still inadequate. So I took off the cylinder top housing for an inspection to check that all was well. On the closer re-inspection I spotted something I missed before. As I mentioned in post #11 there are 4 check valves consisting of a rubber washer, an aluminum backing for support, a spring and a bolt. 3 of the aluminum pieces had holes sized just slightly bigger than the bolt used to secure it in place. And one odd ball that looked exactly the same but the hole was about 25% bigger than the other 3. This was not on my end as all I did was replace the spring. Being that the hole was oversized it allowed water to by pass the check and cause pressure loss. Also I believe this is why the bolt worked itself loose in the first place. I bought 4 new rubber washers, aluminum backings and springs and installed them. I figured I had surely rectified the situation and am sure glad I didn't invite my wife to the "flick the switch ceremony". There seemed to be improved flow but still not up to snuff as my neighbour has the same pump and I have seen what it is capable of.

I think it boils down to the fact that I bought the 'lemon' of the group from the local shop. I can hear there is just too much mechanical resistance during operation but I am not sure where it is coming from. I believe this is why the motor is overheating and flow rate is inadequate (voltage drop during the day when it usually operates is sound). The Mitsubishi motor has been a real trooper with all the abuse though. Actually I am surpised the overload set at 125% of FLA allows the motor to keep running. Maybe I bought a copy that doesn't even actually have any guts. I'll have to buy an amp probe one of these days to see what is really happening. On to priming the pump....

Sezze mentioned that this pump is self-priming and so did the shop where I purchased it (one does still have to prime the drop pipe however). But I couldn't help but wonder why does it have those 2 big brass looking bolts in the top of the cylinder housing where one reads, 'EMA' (see photos in OP). I thought the air bubbles were coming from the trapped air at the top of the housing. So with the pump off I primed the drop pipe, the feeder pipe to the storage tank and primed the pump cylinder housing through the bolt holes. Re-installed the bolts and flicked the switch. No air bubbles!.... but now I had a strong chugging effect and flow was still inadequate. So, I have since allowed air back into the housing and decided that I have no idea what these bolts are for as you wouldn't be able to prime the drop pipe through the bolt hole as the check valves will not allow it.

So thanks for the offer hawaiiman. Maybe there is some sort of small hole somewhere at the top of the drop pipe where there is not enough water pressure for water to leak out but allows air to suck in during operation? If it wasn't for the sound of mechanical resistance in the pump I would bark up that tree. When I get around to buying a new pump body and swap the motor over I will dismantle the 'lemon' and see if I can find the issue. At least I'll have some spare parts kicking around.....