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Plugged hydro line?

Ptom

Solar Enthusiast
Joined
Oct 22, 2022
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121
My Harris hydro (grid tied 24 VDC, 900 watts) has been in operation for 17 years, with no issues. This spring when I put it back in operation, the 3" HDPE fusion welded 1/4 mile long line appears to restricting the flow. Over this weekend I inspected every inch of it (it is not buried, too rocky, and year round/winter use was never intented) and could see no kinks etc. The piping is used in industrial applications, is heavy wall, and is not leaking. But, it's like I'm only getting about 1/4 of the flow I should. It's only inlet is thru a Coanda screen, 1/8" openings, and every year I open up the bottom and let it roar, to clear out any sediment, which is always minor. If there was a way I could send a camera thru it, I'd do it, and there is, but not 1/4 mile. My next try may be just to open it up at the bottom and let it run unobstructed for a few days.
 
I cleared a long drain with a brush ball on the end of a long rope. Using rods I got the rope from one end to the other, attached the ball and another long length of rope. I could the pull from either end and get the brush ball to run the full length change direction and repeat. Got the drain cleared and the removed all ropes and the ball.
 
Its obviously not tree roots or anything like that. But if its run dry for a while, there may be stuff starting to grow in any trapped sediment.
With a 1/8 screen, it can only really be sediment, but there may be plant seeds buried in that sediment.
Open it right up, and let it run for a while.
If that does not clear the blockage, you will need to start measuring pressure drops along the line, with both the available flow, and fully blocked off at the low end.

Running fully open with reduced flow, there will be almost no pressure drop after the blockage point, and expected near full static pressure up ahead of the blockage point , if the remote end is running fully open.

Start in the middle if the pipe run. Then at 1/4 and 3/4 of the length. By a process of elimination you should be able to narrow it down to a quite short section that you can then deal with more easily.
Record all your pressure readings for future reference.
 
I got a sewer jetter, small hose with nozzel to use with pressure washer. Only about 50' long, you'd have to cut and splice to use one.

A roll of smaller poly pipe with lower pressure pump might serve the same purpose.

Conventional sewer snakes are another possibility.

Another is just pumping water through fast, or at higher pressure if completely blocked.

Any of these may work better from the lower end, so things can run out.

There are magnetic wire fishing kits. You could pull the magnet through to locate obstruction.
 
A quarter mile is a long way.
But if you can narrow it down to a short section, I think you might be able to identify a dip in the pipe just by looking.
 
Running fully open with reduced flow, there will be almost no pressure drop after the blockage point, and expected near full static pressure up ahead of the blockage point , if the remote end is running fully open.
I like this test the best, you can drill and tap 1/8" or 1/4 NPT holes in the pipe and screw plugs into them to seal them off. Successive approximation (start at halfway point, see how far water shoots into the air, then do the half of the blocked side, rinse, lather, repeat) should find it for you pretty quickly.
 
I got it solved, simply by opening it up at the bottom (no jets, the 3" line unobstructed ) and letting it run wide open for over 48 hours straight. I think what happened, sure actually, I jumped the gun in getting it back on line, while there was still a large drift directly over a section of the line that doesn't totally drain due to a hump in it caused by the terrain. Some remaining ice slowed the flow possibly, allowing the sediment to build, sediment heavier than usual the rest of the season because of the heavy spring runoff. Once the normal flow is established, any sediment is continually whisked thru the system without any harm. I've seen other hyrdo installs, with very involved catchments that nicely channel the water in a controlled fashion over the intake screen, with provisions made to allow any sediment to settle before entering the pipe. Most of these involve concrete and escavation in or around the streambed, and most don't have the extremes of flow this stream has.
My intake is simply a 8" pipe jammed into the county culvert at the top of my property, with a trap door at the end and a slot cut in the bottom, lowering or raising the end trap door controls how much water hits the screen. On the initial setup, it took maybe 15 minutes to find a place for the screen box, move a few rocks, set the pipe (which rest directly on the screen box) and I was in business! The main benefit, besides it being quick and easy, was that it involved zero disturbance to the streambed, which my state water board discourages, without more permits and inspections and general hassle. The other benefit is it positions the box as high as possible, giving more head pressure, any other arrangement would result in a loss of head by a few feet and that would be intolerable! After 17 years, I think I can say it's crude as heck, but it WORKS. I have never jumped the gun and turned it on with snow still on the ground before, I got sloppy and that late spring heavy snow storm didn't help, next year I'll, like all my earlier years, wait until it's ALL gone before booting it up. I am now back to enjoying the warm fuzzy feeling knowing I'm putting out 33-34 amps at 25.6 volts, into my grid tie account, for the next several months, which still has a surplus of almost 5,000 KWH after getting thru the winter, by late fall it'll be back up to it's usual 8-10,000 KWH, as i also have about 9 KW of PV. Thanks for the various suggestions!
 
I got it solved, simply by opening it up at the bottom (no jets, the 3" line unobstructed ) and letting it run wide open for over 48 hours straight. I think what happened, sure actually, I jumped the gun in getting it back on line, while there was still a large drift directly over a section of the line that doesn't totally drain due to a hump in it caused by the terrain. Some remaining ice slowed the flow possibly, allowing the sediment to build, sediment heavier than usual the rest of the season because of the heavy spring runoff. Once the normal flow is established, any sediment is continually whisked thru the system without any harm. I've seen other hyrdo installs, with very involved catchments that nicely channel the water in a controlled fashion over the intake screen, with provisions made to allow any sediment to settle before entering the pipe. Most of these involve concrete and escavation in or around the streambed, and most don't have the extremes of flow this stream has.
My intake is simply a 8" pipe jammed into the county culvert at the top of my property, with a trap door at the end and a slot cut in the bottom, lowering or raising the end trap door controls how much water hits the screen. On the initial setup, it took maybe 15 minutes to find a place for the screen box, move a few rocks, set the pipe (which rest directly on the screen box) and I was in business! The main benefit, besides it being quick and easy, was that it involved zero disturbance to the streambed, which my state water board discourages, without more permits and inspections and general hassle. The other benefit is it positions the box as high as possible, giving more head pressure, any other arrangement would result in a loss of head by a few feet and that would be intolerable! After 17 years, I think I can say it's crude as heck, but it WORKS. I have never jumped the gun and turned it on with snow still on the ground before, I got sloppy and that late spring heavy snow storm didn't help, next year I'll, like all my earlier years, wait until it's ALL gone before booting it up. I am now back to enjoying the warm fuzzy feeling knowing I'm putting out 33-34 amps at 25.6 volts, into my grid tie account, for the next several months, which still has a surplus of almost 5,000 KWH after getting thru the winter, by late fall it'll be back up to it's usual 8-10,000 KWH, as i also have about 9 KW of PV. Thanks for the various suggestions!

No pictures to share?😟
 
I have a friend who makes a partial living off his YT channel, call him a pro video guy, in a week or two I'll post a link to a video we will be doing, after the trees get fully leafed out. The last one he did about my wood boiler/thermal solar panel seup got over 2 million views! Pretty surprising to both of us, even the ones with his really good looking girlfriend (now wife, oh well) didn't get as many, go figure! I love the numerous comments about how much all the electricity must cost me for the pumps. First off, they draw only around 50-65 watts each, and more importantly, all my power is also free.
 

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