Doesn’t the water get dangerously hot (for the pump) after circulating for a while?
Great idea by the way.
Nope, I use a shurhold for days on end making water in a static system. Gets warm, but shurholds can run dry even. Not recommended, but no problems when running dry on regular occasions.
I had a same problem and basically returned my original Shurflo pump which didn’t have an internal bypass and bought another Shurflo pump with the same specs (1.4gpm 60psi) but also has an internal bypass. Problem solved and lesson learned.
I could have built an external bypass system using the original pump, but opted to switch to a pump with an internal bypass which is a much cleaner approach. Funny thing is that the pump with the internal bypass was $10 cheaper than the pump without the bypass. Go figure. It also cost me the shipping cost both ways ($10 each way) to return the original pump. But might have cost the same in parts to build an external bypass setup anyway.
I use this pump in 3 different applications:
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I produce filtered water and store it in 6 gallon water containers (bought from Walmart) and use the pump to draw water from these containers to feed my wfp pole. I put a ball valve on the output of the pump to control the flow. Seems to work well as long as it’s a pump with an internal bypass.
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I use the pump to draw filtered water from my water containers to flush out impurities from the RO membrane at the end of the job to keep the RO membrane clean.
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When the flushed water coming out of the RO membrane in 2 above gets to be around the same TDS level that normally comes out of the RO permeate output, I start storing this water in a container instead of letting it go down the drain. Once my waste water stabilizes to under 10ppm, I use the pump to run this “waste” water (albeit fairly clean at RO permeate TDS level) through the DI cartridge of my Wash-iT to purify it down to 0ppm again. No sense in letting this “waste” water go to waste.
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The pump is cycling because of a pressure drop - - this can either be a small leak (Fix it) or your hose is expanding (this is more comon in warm weather).
Personally, I found the easiest way to fix this is to simply turn the cut-off pressure down a bit. These pumps have a small adjuster in the pump head (the black plastic part) you just turn it anti-clockwise to reduce the cut-out pressure. Most 100psi pumps are adjustable down to 60psi.
Before anyone goes nuts & says 60psi isn’t enough - IT IS!! 1psi of water pressure will push water vertically upwards about 2’ (Google it if you don’t believe me), so a 60psi pump will go 120’ high. Take off a little for hydrostatic friction, and you’re still comfortably above the highest WFP work you’ll ever have. Adjusting the cut-out pressure does not affect the pump speed or flow rate.
The benefits are less pump cycling, less leaks, less pressure on connectors, less problems with hoses ballooning (especially with hot water), less strain on the pump so probably longer pump life, and even marginally longer life on your WFP battery!
Hm, I thought it was the other way around. Usually the pump turns off when back pressure from the outlet is built up to greater than the setting on the pressure switch (either due to turning off a valve or a pinched hose or simply a long small inside diameter hose with too much internal resistance) .
Turning the adjuster counterclockwise would decrease the setting on the pressure switch, so the pump will turn off sooner at a lower pressure build-up. Turning the adjuster clockwise increases the setting on the switch to turn off at a higher pressure build-up. [B][I][U]Here’s a link[/U][/I][/B] of a youtube video and you can see at around 1:30 minute mark, the guy turn down the pressure switch setting (counterclockwise) and the pump starts cycling on/off, and he turns up the pressure switch (clockwise) and the pump would stop cycling.
However, if your pump is rated at 60psi and the pressure switch is set at 60psi, then turning up the adjuster further is not going to help because you can’t get it to pump more than its rating anyway. Well sometimes you can if the pump is designed with some margin in there and can run a little higher than 60 psi, but you know what I mean.
Trust me - tried & tested solution - lower pressure = less cycling. 
Hey guys, I’ve just built a pump box with a 100psi 1.8gpm shurflo pump. No bypass. I’ve lowered the cutoff adjustment as much as possible and when I kill the water by pinching the hose the pump stops, but cycles about every 3 to 5 seconds. Any tips on how to make this go away? If I put in a bypass like the one in the picture will I still be able to on-demand turn on/off the pump or will it just keep on flowing through the bypass? I have to keep the on-demand-ability to conserve water and battery life.
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Hi Ben, my pump is a Shurflo 60psi 1.4gpm with an internal bypass. When I stop the flow, the pump will turn off. When there’s some back pressure but I don’t stop the flow completely, then the pump continues to run.
Before that I had a pump with the same spec except no internal bypass, and I had the same cycling on/off issue like you have. I did try to lower the cutoff point on the pressure switch like Njones suggested above, but it didn’t help solve the cycling problem. Increasing it helped a little bit, but it didn’t solve it completely either. Increasing the cutoff point just slowed down my cycling frequency but it still happened. The only thing that helped solve the problem completely was with a bypass. In my case, I returned the old pump and bought a new one that has an internal bypass from the same vendor.
Thanks a lot for the response! If you’re having success with a bypass I’ll try that before returning it. I don’t see why an external bypass or internal one would make a difference as long as they still turn off when I close the valve, although I don’t know a ton about this. Appreciate it.
Does anyone with an external bypass have trouble with turning the pump on and off when killing the water?
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My problem is fixed. Very simple solution. Didn’t need any bypass. Just a wcr garden hose to push fitting to pole hose. The 100psi pump would actually push a tiny bit of water out of the garden hose quick connect and that caused cycling. With a solid connection cycling went away. Works perfectly now.
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Glad to hear. The garden hose to 5/16 push fitting is what I use, too. Didn’t realize that you were using quick connect stuff. I can see how that can throttle the water flow.
But now if you get too much water flow to your liking and start using a valve to dial back the amount of water to reduce waste, you may start running into the cycling again. This is where the bypass is useful. Or a better (but more expensive) way to control the water flow is with a flow controller hooked up to the pump.
The application where my previous non-bypass 60 psi pump was cycling was only when I tried to pump pure water through the RO membrane to flush out impurities, or when I pump semi pure (40ppm TDS) water through the DI cartridge, meaning there’s back pressure trying to push water through these filters. Otherwise, I had no cycling issue when pumping directly to a 5/16 hose that goes to the brush.
For now I’ve got a $10 analog control with a dial from Amazon and it works great. I made the whole trolley for less than $250. A digital one will be a future upgrade. Thanks for the pointers!
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Wow $10 for an analog controller sure beats a $160 digital controller any day!
Would you mind sharing the link to that analog flow controller from Amazon?
Video! Video! Video!
Joshua Adriance
Pure Water Window Cleaning
514.867.8324
www.pwwc.ca
My bad, it was $13, I don’t have the best memory sometimes. There are even cheaper ones, but this one has the wired extension for the rotary pot so you can better place it, instead of having the whole board with the rotary fixed on it. It even came with an extra rotary pot. Its got a built in fuse too. Works amazing. You can adjust flow from a drip to shooting like 15’. Doesn’t have all the fancy features of the digital one, but no complaints for the price. The rotary does not have an off position, so I have a switch too. I should do a video soon when I have some time.
http://www.amazon.com/gp/product/B00CW82ZPG/ref=oh_details_o00_s01_i00?ie=UTF8&psc=1
