Higher lift 12vdc pump??

icarus · January 2012

I am building a off grid cabin for a client and have a problem with the pump. I installed a Shurflo 12vdc conventional pump,that is speced to lift 12'. The pump is located ~5' above the lake level. When first install as a test, the pump primed fine and delivered. When I installed it in the building, the pump would not self prime, and even priming the line through a priming port it often wouldn't pump. I am guessing that the suction line is too long, (~100' of 3/4 pex) I am also wondering if the in the lake check valve is too strong and the pump can't open it.

Does anyone have an idea for a similar style pump that will reliably lift the 5' with the long suction line? If it were me, I would have installed a 9300 submersible, but that is not an option now.

All thoughts welcome,

Tony

waynefromnscanada · January 2012

Re: Higher lift 12vdc pump??

The long suction line, unless it's crushed someplace, should make no difference as long as the overall vertical lift is only 5 feet. Will be different if it has to go up over a hill before it gets to the camp, but other than that, the only difference between a long or short horizontal line would be all the extra air that would have to be sucked out before the water gets to the pump, then once the water does get there, depending on the flow rate, friction losses could be a problem, possibly reducing flow rate, but not a problem with priming. Any chance the foot valve has sunk in a muddy bottom, clogging it? Or gravel/dirt caught in, and holding the foot valve open, allowing the water to drain back after the pump stops?
Other than that, a hole in the pipe or a leaky joiner or connection in the pipe allowing air to be sucked in, or a problem with the pump. Not familiar with your particular pump though. Similar water systems I live with every day. My well is roughly 250 feet down over the hill, with a total vertical lift of about 20 feet. The positive displacement piston pump in the basement sucks the water up that line every time it runs. Primed it 3 years ago when it was first put into service, and never again since.

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

If you wanted to try another Sureflo, this is a a new 5.7 GPM that has 5 diaphragms. they are much more powerful that the older ones. I use a different brand, but they are the same as Aquatec has the patent on them. 100 ft is a long suction line, How far up the line is flooded ?? Do you even need a check valve ?? With a diaphragm pump all you need is a strainer, the pump has a check valve built it..

Extreme™ Smart Sensor™ 5.7
Model Numbers OEM/Aftermarket : 5900-0201, 5900-0211

icarus · January 2012

Re: Higher lift 12vdc pump??

Wayne,, thanks for your advice.

The foot valve is on a rocky bottom, and in fact is suspended off the bottom. There are no fittings between the foot valve and the pump, except for the 3/4 to 1/2 reducer and the female thread adapter. I would suspect sucking air,, but it worked fine for a while, then I drained it for the winter. The owner then tried to prime it once again, called me and I couldn't get it primed again. Even if the check valve is stuck open, it should prime eventually, but it doesn't seem to. I suppose the check valve could be stuck closed.

It wasn't an issue to get fixed before freeze up so I had to let it go. Of course now I can't deal with it until break up, but I am trying to get my ducks in a row. The client expects to come to his camp, flip the switch and have water, and I'm going to look bad if I haven't figured it out!

Tony

PS This is why I prefer submersibles,, except when THEY fail. Mine is currently under 4' of ice, and if it fails,, it's back to buckets!

waynefromnscanada · January 2012

Re: Higher lift 12vdc pump??

I have seen a foot valve stuck shut, but of course it's very rare. Excellent move to have it suspended up off the bottom. If no air leaks, I'd suspect in your case, either a stuck foot valve, or a problem with the pump. Sucks

When we had our cottage, we had an inverter powered standard 120 VAC 1/2 Hp Franklyn powered submersible out in the lake, with it's check valve removed, and replaced with one up in the cottage. I actually set up identical (except grid powered) systems at 3 other cottages for friends around the lake. For winter closeup, we just shut off the switch, opened a couple of valves, one bypassing the check valve, the other allowing air in, and the water drained back to the lake. Thus no water line freeze damage. Come spring we closed the valves, flipped the switch and in less than 10 seconds we had water. Loved it.

BB. · January 2012

Re: Higher lift 12vdc pump??

Ice in the line? Freeze damage to pump diaphragm or valves? Debris in pump valves? Debris in pump suction screen?

Just guessing--I am sure you have looked at these possibilities.

-Bill

icarus · January 2012

Re: Higher lift 12vdc pump??

No ice, I installed in in August,, I just didn't have time to deal with it this fall. Also, brand new installation, and absolutely clear water.

My real question is does anyone know of a similar style pump with just a bit more lift capability.

Tony

vtmaps · January 2012

Re: Higher lift 12vdc pump??

icarus wrote: »

I am also wondering if the in the lake check valve is too strong and the pump can't open it.

I doubt the check valve is the problem here (since it worked for a while), but in general I prefer to use a swing check valve in a situation like this. Swing checks have much less resistance to flow than regular (spring type) check valves.
--vtMaps

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

The most powerful I know of is the post # 3. I am guessing that when you said it was primed that means the pump had some water ran through it. A diaphragm pump needs to be wet to get any suction. I have installed a new one a time or two and didn't and the are slow to prime that way. I never put a check/foot valve on them, they are not necessary. One more problem and then the lie is not self draining. Yes, they have to be air tite or you have a problem.

waynefromnscanada · January 2012

Re: Higher lift 12vdc pump??

Agree that in your situation, a check valve not really necessary, just a screen to keep out bugs and leaches etc. Also agree re having the internals of the pump wet with water. Even a positive displacement piston pump won't prime unless the valves etc are good and wet, and kept so until it's successfully primed.
Yes, leaches! One time my sister was getting ready to wash her hair, had the water valved just perfectly for the job, and suddenly the water slowed right up, - - - then - -- - -PLOP! Out came a frigging leach and down the drain it went! It had made it through the piston pump in one piece! After that I replaced the missing screen on the foot valve!

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

I wonder if you could inject some water on the suction side without any air leaking in if it would increase the suction lift. If the pump is has suction there should be pressure building on the out flow. The way I set them up, I have a bypass where the pump will run in a loop from the tank, The tank is filled from city water that is run into a tee that pump also feeds. If I open the fill valve to the tank the pump runs in a loop from the tank, back into the tank fill line.

icarus · January 2012

Re: Higher lift 12vdc pump??

Black cherry,

Sorry I missed your post #3 as we over lapped. What is the model number of the 5 diaphragm shuffle?

Tony

Ps. I believe I have a swing valve and screen,, but I confess I don't really remember. I'd did include a priming tee in the line so that I can pour a bucket or two of water down the line to fill it. I will try the bigger pump, and eliminate the foot valve and see how that works.

My thinking about the for valve was to keep the line from draining back, even though the pump has a check valve in it so that the pump won't drains the P-Tan. 100 feet is a long run, and the potential to introduce air seems reasonable.

Tony

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

This the pump that NAWS should have or get. These are really nice pumps, 5,7 gallons @ 65 psi is a whole lot of water. They'll run a whole house with no trouble. I replaced many Centrifugal pumps with them. When you look at the pumping curve, they are much better and 12 V @ 10 amps to boot. As soon as you pick one up, you'll know what I mean, they weigh about 10 lbs.

http://www.shurflo.com/rv-products/rv-pumps/extreme-series-water-pumps/extreme-series-smart-sensor-57/default.html

These are the ones I use. They are about the same, Johnson Pump has one also. These are all variable speed pumps with a soft start.

http://www.google.com/products/catalog?q=aquatec+pumps&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&tbm=shop&cid=14254538880798628797&sa=X&ei=5DsDT7eGNtKatwfir-3QBg&ved=0CHUQ8wIwBQ

icarus · January 2012

Re: Higher lift 12vdc pump??

Very good,, thanks, What they don't list in the specs is the lift capability, that is what I am most concerned with.

I will look into it.

T

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

Here is data on the Aquatec, they should be about the same. It says 9 feet. I know it will prime higher because I have one at about 12 feet. You should be able to Google around and find the Sureflo , if that the one your interested in.

http://www.aquatec.com/sg_userfiles/Variable_Speed_Pumps_Data.pdf

mike95490 · January 2012

Re: Higher lift 12vdc pump??

what are the chances a critter chewed on the line, and it has an air leak ? Try a wet/dry shop vac at the pump outlet, the internal valves should open (diaphragm right ?) and the shop vac should be able to suck 5', or st least help you fiind a pinhole in the line. PEX is not sunlight resistant, and when warm, may not be stiff enough to resist suction collapse, pinching itself shut.

icarus · January 2012

Re: Higher lift 12vdc pump??

Just to be clear (probably not,, but I'll try!) I did the installation on a new building in August, field tested it and it worked fine, and then drained it. We were shutting down the project for the season, and the owner tried to reprime it a day later and he and I could not get it primed to save our lives. I don't think that there was enough time in a day for the pipe to either be eaten, nor eroded against the lake shore or anything.

To my chagrin, I had to leave it in August, and couldn't get back to it before freeze up,, so I couldn't solve it. I am just trying to get a handle on it, so that when I get to it,, I know which way to go. I am guessing the 5 chamber Shurflo would do the trick, if previous posters experience is correct. I have a note into both Shurflo as well as NAWS to see if they think the other pump would be a better alternative.

Once again,, thanks for all the help,

Tony

icarus · January 2012

Re: Higher lift 12vdc pump??

So,, I got a reply from Shurflo, the first was:

100 foot of 3/4 pex is way too long for the suction side - it needs to be within a few feet of the water source as our pumps - push better than they pull!

When asked what pump they had that might do it was this:

According to Application Engineering we don't have anything, but you might check with Depco Pumps at 800-445-1656.

Good luck,

So that leads me back to square one. So here is the design parameters. Total lift,, ~8', (into 50 psi) length of 3/4" suction line,,~100'.
12 volt power source. This is a summer only application, very part time.

The obvious solution would be to move the pump the 100' to the water. The two problems there is A: it then becomes a service issue in that it has to be installed and removed at the beginning and end of the season, and my client is not particularly handy. The second problem B: is the considerable voltage drop in the 100' of 12 volt wire. A linear current booster would help,, but I don't like that idea very much.

So,, any ideas of a comparatively inexpensive 12 vdc pump that might suit the bill? In retrospect I would have speced the 9300 submersible had I know this was going to be an issue, but that has issues as well. One question is, if I install a impeller type pump, and prime the line full at the pump, will it draw better than the diaphragm type Shurflo pump?

Tony

westbranch · January 2012

Re: Higher lift 12vdc pump??

Tony, does the 'other' location have 12 or 24 Volts?
if 24 what about a stepdown to 12 v close to the pump?

e

icarus · January 2012

Re: Higher lift 12vdc pump??

Eric, the only power source is a 12 volt deep cycle, which exists only to power the pump. The house is genny supplied, but with limited tank volume the 12 vdc is the easy solution. The battery is recharged with a charger when ever the genny runs. The pump will only have to deliver ~100 gallons per day.

I suppose I could relocate the pump to the far end of the house which would shorten the suction line to ~ 60' but I still have to lift the 5-8'.

Tony

Blackcherry04 · January 2012

Re: Higher lift 12vdc pump??

I wonder why i worked when you tested it. Something had to change. I re-did 2 sump pumps last summer and put check valves in them. There were regular valves with a flapper. I tested both in a 5 gallon bucket and they worked perfectly. I installed one and had the other set up as a drop-in replacement. We had a big rain last month and water was coming up in the stairwell, I ran and checked the sump and the pump was running , but not pumping. I am thinking the Impeller was bad, I switch pumps, same thing, wouldn't pump. I now thinking the line was plugged, I check it, nope, it's clear. So now I am saying, has to be the check valve or the impeller, Impeller was fine. I took one apart and yanked the flapper out of the check valve and put it back in and it worked perfectly.

The only thing that changed was the temperature of the water. The flapper was EDM soft rubber, but that's the only cause I could figure out. Both of those pumps had worked for a couple years without a check valve. I thought they would last longer with one and not run as often. The head is only about 5 ft., that didn't change.

icarus · January 2012

Re: Higher lift 12vdc pump??

I too am guessing it is the check valve,, but I need the system to be near 100% reliable so I am still looking for alternatives. At least I have several months to work it out.

T

firerescue712 · January 2012

Re: Higher lift 12vdc pump??

Here is something we do in the fire service. At our suction strainers, there is an input for a pressurized hose. Water is pumped from the fire truck to this strainer. It boosts the water flow and also helps to maintain a draft (suction). The main setback is the necessity to have water available to pump between the pump and the strainer before the intake hose has its air purged. If your pump is a positive displacement pump, the pressure from the weight of the water in the line might be too great on the intake side when the pump is not running. This might cause a strain on the internal seals of the pump. This could lead to a loss of prime. Why not add a quarter turn valve a few feet from the intake side of the pump on the suction hose. At least this could be turned off when the pump will not be used for a while, thus keeping the hose primed up to the valve. Just offering suggestions.

icarus · January 2012

Re: Higher lift 12vdc pump??

Not a bad idea,, I could use a normally closed 12 vdc solenoid valve somewhere on the suction side,,,

Still looking for a easy pump solution,

T

Higher lift 12vdc pump??

Comments

Categories