Water supply set-up questions

SystemSystem Posts: 2,511 admin
I have a small cottage which sits 130 ft back from the lake.
My set-up is: The foot valve to the pump is Ø1” poly pipe 22 feet long on a 10 foot elevation. From the pump (set at 40/60-psi) to an 8 gallon bladder pressure tank to the cottage kitchen tap is 120 ft on a 21 foot elevation through a 2” dia polypipe, reduced to ½” for the tap hook-up. I use a 3.5gpm Shurflo 12 volt water pump with it’s own 11 watt Unisolar panel charging two 45 Ah Marathon AGM batteries and a SunGuard charge controller.
When I first installed everything 2 years ago, I only had a 5/8” garden hose for the 120 ft run and had GREAT pressure and flow rate – it could fill a 5 gallon bucket in 1 minute 13 seconds as the pressure tank emptied and then I got acceptable pressure from the pump only output but (understandably) not the gpm flow rate – it took almost 2.5 minutes to fill that same 5 gallon bucket. When I installed the 2” polypipe my pressure dropped and the gpm was WORSE!! It now takes almost 4 minutes to fill that same bucket. My thinking was a larger delivery pipe would have less friction and so more flow/pressure…….. instead it’s worse – is this because the weight of the extra water in a 2” pipe versus the 5/8” garden hose ?? What is going on here ? What am I not understanding ? What would be the optimal pipe sizes to be using to get great pressure AND gpm flow rate?


  • pcguy2upcguy2u Solar Expert Posts: 139 ✭✭✭
    Re: Water supply set-up questions

    I believe your logic on the 2" pipe is correct and that there is a coincidence that is masking the real problem. I would be looking at some other aspect of the installation - something else is causing the problem.

  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    I am not clear on a couple of things.

    First, where is the pump? At lakeshore, or at the building? In other words are you sucking water pushing it the 120'?

    Second, where is the foot valve?

    As to pipe size and pressure, the size of the pipe has no bearing on the pressure at the bottom end of the pipe. The only thing that matters is how high the top end is. For example, 30' of head into a 2" pipe will produce the same pressure as the same 30' into a 1/2" pipe. (Yes over some distance there would be a drop in the smaller pipe due to friction losses but for the sake of this conversation we will call them the same) If memory serves it is about .4psi/foot so 30' would be ~12psi.

    Once the pressure tank is charged, the discharge rate out of the tank should only be regulated by the size of the pipe on the discharge side, and how far open a valve is. One thought is have you checked the pressure of the bladder in the tank itself. Generally the bladder pressure should be ~2psi under the minimum set pressure. (Having said that, I have mine set down to the minimum threshold that my demand water heater will turn on. This way I get a lot more volume out of the tank before it runs out of enough water for a shower. This allows me to turn off the pump at night if I choose and still have plenty of water). If the outlet pressure is dropping off maybe it is a restriction in the outlet piping/valves?

    Please describe your system a bit more,

  • System2System2 Posts: 6,290 admin
    Re: Water supply set-up questions

    The foot valve is 9" long and Ø1.5" and at the FOOT of the entire system (in the water - nine feet deep - held 1 foot off the lake bottom so it doesn't suck mud etc).
    Attached to the foot valve, on a Ø1" polypipe, twenty-two feet away, at the lakeshore and 1 foot elevation from the water level is the Shurflo pump.
    The pump sits directly on top of an 8 gallon bladder tank and is plumbed IN (suction side)with the same Ø1" pipe and OUT (tank/pressure side) with Ø1.5" braided flex-pressure hose.
    The bladder tank has a TEE for water in Ø1.5" & out at Ø2" for the main run up to the cottage, PUSHING the water the 120' distance including a 21 foot elevation.
    The pump controller is set for 40psi ON and 60psi off....... the bladder tank is compressed air charged (when the tank is empty of water) at 36 psi (4psi below pump cut-in pressure).
    At the cottage end there is a reducer changing the diameter back down to 1/2" for the copper plumbing.
    All the plumbing is now installed for the kitchen and bathroom sinks, toilet, and most important - the SHOWER !!!!
    I have thought, measured, researched and calculated all this out and still can't figure out why I have this problem - unless I can get the flow up to a reasonable rate (2gpm ??) I won't be able to install my Bosch instant water heater.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,963 ✭✭✭
    Re: Water supply set-up questions

    I'd guess its nothing to do with the plumming and you have seriously discharge your batterys. 11 watt panel isn't much for 1000 w/hr of batterys. At best it might keep the self-discharge from killing the batterys but it would take probably 200 hours with no load to fully charge the batterys in full sun.

    What is the battery voltage at? Since you are looking at a instant water heater ( I assume you then have electric ?) throw a battery charger on the batterys and when fully charged redo the flow tests
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    SG is probably correct.

    Having said that, having a bunch of experience pumping water from the lake, AND with demand water heaters here is my observation.

    Try not to rely on the pump to pump the volume for the water heater. If you only have an 8 gallon tank, you only have an effective volume of ~4 gallons, before the pump must turn on. Consider adding a bigger tank, either at the lakeshore, or in the building. The pump won't care as you are pumping into pressure regardless.

    As for solar pumping, if you can size your system to only have to pump during the day, but provide enough volume for 24 hours you will be further ahead. I shut the breaker off to my pump in the evening, knowing that there is plenty of water to get through the evening and the next morning. It is much easier to use the sun directly, rather than discharging the battery and then recharging. So for example, my pump draws ~10 amps. In full sun, the load is taken fully by the panels, but it I pump at night, 100% has to come from the batteries, requiring the same 10 amps out of the battery, PLUS the inefficiencies of the charging equipment, and the fact that you can only get back ~80% into the batteries. (In other words, it will take~120% to pump from the batteries rather than from the sun if this makes sense.)

    Do a calculation and figure out how much water you really use in a day, and how long it takes to pump it to the needed pressure, then size you PV and batteries to make this work. If you haven't purchased your water heater yet, you might consider a Paloma "legacy" series water heater. These heaters are as efficient as the Bosch, but they are way more tolerant of lower pressure/lower volume.

    Remember that a pressure tank of any given volume will only deliver ~ 1/2 of it's volume. Also consider lowering the bladder pressure to ~15-20psi regardless of the pump switch pressure. Do this test. Leave the bladder psi where it is, pump it full. Time and measure the volume until it runs out. Then lower the pressure as suggested. I think you will find that you get more volume with the lower pressure. In this case, the pump will turn on as set at say 40psi, but the volume will continue quite well (for a bit) while the pump begins to contribute AND the tank still contributes. You are tricking the system to deliver a bit more water. A bladder tank set to any pressure will deliver that pressure until the tank gets below the bladder pressure, and then the water will stop very suddenly. If you have the bladder pressure lower, it will push out water until the pressure gets to the set pressure and then it will stop. ( I realize I'm not writing this very well, but I think I got the point!)

    Good luck and keep us posted.


    PS The 21' of elevation will drop the pressure ~8 psi. The 120' horizontally will only drop it as a result of friction loss, ~1psi? Bigger pipe will reduce it to almost zero. If you are pushing up a 2' line it should be fine. Looking at your set up a bit more, an 8 gallon tank is way too small, AND, not looking at the specs for the pump, but to expect it to pump 2-3gpm against 40 psi is a bit much as well. For example, the sure flow 2088 will pump 4 gpm at 0 pressure, but only 3 gpm into 30 psi. Pump it into 60psi and the output will decrease further. Consider setting the on off pressure 30-50 instead of 40-60psi. That will make it pump faster.

    Also, consider installing a pressure gauge in the house (It just has to tee into any line) so that you can monitor the pressure and see how low it is getting. You can also consider pumping water with a generator supplied charger on the system. If you have a big enough tank, a few minutes of running the generator will keep the batteries in form if need be. I don't know what other grid or generator power you have or are going to have.
  • mike95490mike95490 Solar Expert Posts: 9,037 ✭✭✭✭✭
    Re: Water supply set-up questions

    Check the air charge in the bladder ?

    With a small pipe, the flow velocity is high enough to move air bubbles thru the system. with a larger pipe, you may have a "pocket" of air trapped in the pipe.

    Maybe try going back to the smaller pipe if you still have it around. 11watts is not much

    And like SG says, check the charge in the battery.
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  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    To add to SG'S comment

    Your panel puts out less than 1 amp under ideal conditions. 1 amp is barely enough to keep the batteries float charged, assuming perfect conditions.

    Your pump will draw ~5-10 amp depending on pressure. if you use the pump say 1 hour/day that means 10 amp hours down every day, in a system that can only put in 5-6amp/hours/day. You need more panels regardless if you are going to use this system more than once a month or so.

  • System2System2 Posts: 6,290 admin
    Re: Water supply set-up questions

    Have lots of experience (over 40 years) with this type of domestic water supply system, but not the Sureflow pump itself.
    Some observations:
    a) Pressure on air side of bladder tank can ONLY be properly adjusted with NO water in the tank. (As soon as water goes in, the pressure equalizes and if you adjust it then, you'll throw it way off from where it should be) And the pressure should be 2 PSI below the cut in pressure of the pump switch. Significantly lower air pressure results in the bladder getting stretched and if low enough, will result in early bladder failure (rupture). You should also drain the water from the tank and recheck the air pressure every couple of years, as it will gradually leak out, it finds ways after a couple of years.
    b) The PV is definitely on the small size, very likely too small. I too suspect that could well be the problem. That said, consider how long the pump will have to run to fill that big long new pipe from the tank to the cottage. The battery could well have gotten run down with the extra pump time filling it, especially if it wasn't full up to start with. Personally, I wouldn't use a pipe that large, as the water would move so slowly through it, that by the time it gets to your faucet, it could be a couple of days old in the pipe. Depending on how much water you use.
    c) Water hammer, probably not a problem with a pipe that big, but definitely with a smaller pipe that long, I would install another bladder tank, not necessarily as large, in the cottage, to eliminate water hammer and also instantly give full flow when a faucet is suddenly opened, without having to wait for the 120 foot long freight train of water to get moving. I would have used a 1/2 inch poly pipe and spent the money on a second tank. But that's me, with my experience.
    d) Just make sure the foot valve didn't get partly blocked with old leaves, water weed, an old plastic bag, or whatever, as soon as you can. Otherwise, everything points to a "pump problem", which very likely will be low voltage from the batteries, not allowing the pump to run up to full ability.
    Cheers and good luck.
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    I agree with most of what my friend Wayne says. I had not heard that about rubber bladder tanks. My current installation, (with the lower pressure is quite new) I have never lost any air in a bladder tank, but I have always bought good ones. (No aspersions Wayne, just my observations)
    Unbladdered (is that a word!) tanks can and do lose all their air.

    As for the pipe size. I don't think that it really makes much difference. I have always been advised to upsize pipes in situations like this. I'm sure there are ME's out there who could shed some light. I know that my submersible shureflo suggests a pipe size no bigger than 3/4".

    I agree that a second tank would help. I really don't think that water hammer should be a real issue.

    Keep us posted

  • System2System2 Posts: 6,290 admin
    Re: Water supply set-up questions

    The bladder tanks have a special food grade Neoprene bladder, which keeps the air from contact with the water, but like even the best tire left stored for years in a corner somewhere, in time, the air finds ways to significantly reduce volume. I always like to check every couple of years and top it up if necessary, instead of waiting for 5 years, by which time the air volume has reduced significantly. It usually is not noticed without checking it, unless one notices the "drawdown" of the tank is reduced, resulting in the pump operating more often than it used to, and running for a shorter time, or the bladder has ruptured, which quickly reduces the drawdown capacity. They can go 10 or more years, seemingly working fine, if one doesn't notice the symptoms. During my 15 years as a problem solver with a Canadian plumbing supplier, I've dealt with many hundreds of systems and have yet to see a bladder tank of any size or make, that doesn't in time loose air volume.
    The old non air separator tanks lost their air due to the air being dissolved in the water, and the higher the operating pressure, the faster it happened.
    As to the water hammer, you're right, with a poly pipe that big, for this system there would be no water hammer, the flow velocity is too low. However, if a 1/2 inch 120 foot long poly had been used, as I would have used for this small, relatively low consumption system, it would have been a problem.
    Cheers and all the best
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: Water supply set-up questions

    The first thing that jumps out at me was the solar panel size and the pump isn’t getting enough voltage.

    Second was a plugged or partially blocked intake for the pump in the lake. For 30 years we pumped water out of the bay to water the lawn and gardens and when the flow started to slow down it was time to change and clean the intake filter.

    And lastly was some smaller 12vdc pumps actually pump slower with less load or pressure on the output side. They like to have a good head to push against to get good flow. Maybe by going to a larger pipe your loosing that resistance to keep the pump at a higher pressure (although I would think the pressure tank right after it would do the same thing?) Honestly if you can go back to a garden hose try it and see if that is the problem?

    Just my crazy ideas.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • System2System2 Posts: 6,290 admin
    Re: Water supply set-up questions

    I did more digging and logging.......

    Battery pack read 14.16 at noon Saturday and read 13.82 at 8:45pm as the sun went down last night. First thing Sunday morning (7.20am) the voltage was 13.47. The pump has run through the night.
    The solar panel sits atop a 14 foot tall, 2”dia. pole anchored 5-6 feet deep – right at the beach, on a 40° angle, facing compass due South, attached with #12 low voltage outdoor wiring to the charge controller which is mounted to the inside of the ‘doghouse’ that the batteries, pump, bladder tank etc sit in. From the panel to the charge controller to the batteries the maximum wiring run is 15ft. From the batteries through the on/off switch to the pump is 3.5ft.
    Because of such a small panel I never had a charge controller before but found that the batteries had an ‘oily’ wet spot around the vents around 2pm and occasional ‘bubbles’ & the voltage was up as high as 16.04 so I put the charge controller on and don’t see the venting issue anymore.
    I thought that a small panel on for 7 days a week charging would suffice - I am only at the cottage Friday night until Sunday afternoon – and the pump is on for minimal run times. I fill that 5 gallon bucket maybe 10 times a day- there are only 2 of us.
    I have no electricity at the cottage– my (already purchased) Bosch instant water heater is propane powered and the literature says it runs by a battery spark ignition.
    Tuesday I re-attached the 5/8” garden hose for outside only delivery and here are results of test pumps.(digital watches for times and analog water pressure gauge so they may not be “exact”) – but I DO have a Fluke DVM model #179 so the voltages are accurate!
    Foot valve totally cleaned. Batteries at 14.12, water pressure at 55psi – pump hasn’t run for at least 1.5 hours…… full sunny day – NO clouds, 76°, 10.30am.
    Tap on-pressure & flow great!– 5 gallon bucket 2/3 full in 38 seconds….bladder tank empties, pump starts, voltage immediately drops to 13.52 and water pressure fluctuates 35-40psi…. bucket full in total of 52 seconds – emptied bucket ( tap still running) and re-filled with pump only pressurized water – 2min 11 seconds….. tap off….. pump runs 2 minutes 18 seconds more and stops….. voltage goes up immediately to 13.96, water pressure at ~60 psi.
    Re-set & re-test at 10.50am …. battery at 13.97, water at ~60 psi. Tap on – bucket 2/3 full in 40 seconds, pump on & voltage to 13.50, pressure at 35-40 psi, bucket full in total of 50 seconds – dumped bucket & refilled in 2minutes 20seconds. Tap off & pump runs 2 minutes 8 seconds more & stops…… voltage right up to 13.89 and water pressure 55psi.
    Re-test at 11.10am ….. battery at 13.92, water at ~60psi….. tap on great flow & pressure - bucket 2/3 full in 37 seconds, pump comes on – voltage drops to 13.29, pressure at 35-40psi – bucket full in 56 seconds, dumped and refilled in 2 min 39sec. Tap off & pump runs 2 min 28 seconds & stops – voltage instantly goes up to 13.76 & water pressure at 60psi.
    At 12.35pm the voltage is up to 13.86.
    Changed to 2” delivery polypipe and let it fill with water.
    Some clouds, 80°, 12.55pm start test.
    Batteries at 13.88, water at 55psi……. tap on – bucket 2/3 full in 1min 18sec…pump on – voltage drops to 13.27 & pressure at 15~20 psi…. bucket fills complete in 2min 38sec, dumped out (tap still running) and refilled in 3min 6 seconds. Tap off & pump runs 2 min 11 sec. & stops – voltage up to 13.60 & water at 55psi.
    Re-test at 1.15pm… battery at 13.69, water at 55psi…tap on – bucket 2/3 full in 1min 10 sec… pump on & voltage down to 13.12 & pressure at 15~20psi… bucket fills in 2min 42 sec, dumped and refilled in 3min 17 seconds. Tap off & pump runs 2 min 19 sec & stops – voltage goes to 13.51 & water ~55psi
    Once again ….. 1.40pm – battery at 13.51 water at ~55psi… tap on – bucket 2/3 full in 1 min 19 sec… pump comes on & voltage drops to 13.04 & pressure 15~20psi… bucket fills in 2min 45 sec, dumped & refilled in 3min 19 sec. Tap off & pump runs 2 min28 sec & stops – voltage goes up to 13.4 & water is at 60psi.
    It’s 2pm & getting cloudy and I am wet and discouraged & SWMBO says enough !! she won’t help anymore & she wants water late tonight whether I bring up buckets or the tap works…….. I changed back to the 5/8 hose and hooked it to the indoor copper ½” plumbing and try the kitchen & bathroom taps – they work nice separately but not so good at the same time.

    What next ??? :confused:
    I don't think the batteries are the problem - they ARE used AGM's but still hold good charge -the voltage doesn't seem to drop off too bad under load and comes back in time.
    I do have access to a second pressure tank - but it's a 30 gallon NO bladder tank..... I could put it under the cottage ..... maybe ???
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    So if I am summarizing you correctly, at the first part of the day it puts out something in the neighborhood of 7gpm? A nice amount for a small system.
    Later in the day, using the 2" line, the results are much less?

    A pure test to see if it the battery is to fill the tank to full PSI, drain it until the pressure switch calls for water and time/volume that. That number should hve nothing to do with battery/PV condition as the pump isn't even running.

    Reading your test results it sounds like there is something wrong with the 2" line. The P-tank is at the shore right? So the P-tank feed either the hose or the 2" line right? If that is the case I think you can draw that conclusion. Is is possible that there is a leak underground? Does the pressure drop to zero over time? Is it possible that it is somehow airlocked? I'm grasping at straws here!
    Is it possible that there is some obstruction in the line that you may have missed on install?

    Fluid engineers might have a better answer, perhaps, as suggested the 2" line is too big. That would run counter to my experiance but what the hell, the sheer volume of what I don't know,,,,,,I'll keep thinking.


    PS My intuition says the everything would be happier up at the building. (Don't forget that P-tanks can be anywhere. If freezing is a problem, consider a rack off the floor in some unused space, or attic space or something.
  • BrockBrock Solar Expert Posts: 633 ✭✭✭✭
    Re: Water supply set-up questions

    After this info I am going to go with my 3rd choice first now, that is the 2 inch line lets to much water flow which drops the pressure at the pump below some level and the pump doesn't pump as effectively. I know it sounds crazy, but about 2/3rd of the 12v pumps I have seen pump more GPM's against 25+ psi then if you open flow them. (Done a lot of boat work and pump on them)

    My second guess would be a blockage in the 2 inch line, if you had a pressure gauge at the pump and the house you would know for sure.

    Where is the pressure gauge? Right at the pump before or after the pressure tank or up at the house? If the pressure gauge is at the pump or even at the pump end and it is dropping to 15-20 psi, then the 2 inch line is clear and letting to much water though to keep the pump happy.

    In any case it really doesn’t sound like it’s your panel, charger or battery, they seem to have good numbers and hold up well with the pump running.
    3kw solar PV, 8 L16's, xw 5548, Honda eu2000i, iota DLS-54-13, Leaf EV, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • icarusicarus Solar Expert Posts: 5,400 ✭✭✭✭
    Re: Water supply set-up questions

    Even with a partial blockage in the line, a pressure gauge would read about the same on either end. Brock may be on to something. I haven't had any experience with such a large line on a 12vdc shureflo.

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