here’s what I came up with today.
buried a 1″ black poly water line – about 400′ long, with one coupling in it – from a house to an outbuilding about a month ago. Today I hooked it up to the pressurized line in the basement and connected it to a sink in the outbuilding. Turned on the water. After cleaning a bit of initial flow crud out of the faucet I am left with a situation where when I open the faucet, there is a surge of regular pressure water, then the flow drops off to a a small but steady trickle. If I shut it off, wait for a few seconds, turn it on again, another surge dropping back to the trickle. If I keep it off longer, the surge gets longer, but that’s about it. there is also a hose bib in the outbuilding and it shows the same behavior, so it’s not the faucet itself.
my interpretation is that there is either a kink in the line (from backfilling is all I can think, though that seems unlikely as we shovelled dirt on the line before the backhoe backfilled), or there is some sort of clog of dirt or ? that got in the line.
tomorrow I am heading back to try and sort this out, and I have a not-good feeling about it. All I can think to do is to disconnect and look down into the elbow that comes up out of the concrete in the outbuilding and see if there might be some obstruction in there and then possibly try to blow it out in each direction with high pressure air.
anyone got any other ideas about what could cause this or what might be done to try to remedy it?
Roy
Replies
What size is the supply line in the basement? Sounds like there's not enough volume to keep the plastic line full.
Whenever you are asked if you can do a job, tell'em "Certainly, I can!" Then get busy and find out how to do it. T. Roosevelt
The 1" poly is teed off a 1" galvanized pipe manifold that delivers to 2 other buildings, including one much further away and higher on the hill. The manifold is right next to the pressure tank. Since the other branches off the manifold are all still working OK I am presuming the problem lies in the branch I just hooked up.Roy
I guess the next time you put in a long run of pipe you will test before you backfill?<G>
Did you disconnect the new pipe at the final junction downstream before any valves or fittings? And it still did not deliver a good volume and pressure?
I would start the investigation at the first connection to the system. Disconnect the run at the new tee and see if there is an obstruction in the tee. If you have a valve after the tee inspect that for obstruction. Maybe the valve isn't open all the way.
Dig up the line at the midpoint coupling. Open the coupling and check for obstruction. See if the water will flow properly at least to that point. If not, you may have narrowed the search down to the first half of the run. Try some back-flushing from that point. Hopefully the line is not kinked or crushed. Repeat if necessary with the second half of the run. Good Luck.
Pressure loss due to friction. 400 feet is a long way for a pipe that size. Here's a Google search for some resources.
http://www.google.com/search?hl=en&ie=ISO-8859-1&q=%22pressure+loss%22+friction
Plastic pipe is very smooth; i wouldn't expect much pressure drop through 400 ft of plastic.
What is the elevation difference between the two ends of the pipe?
I run that size 750'. Turns out the vast majority of my 50 psi loss is due to elevation. PAHS Designer/Builder- Bury it!
no appreciable elevation difference, if anything it's a few feet lower, so that shouldn't be the issue. today I will disconnect at the first juncture I can get to on the downstream end - which is the up leg of an elbow where it comes out of a slab - and see if I can find any crud and also see if how the flow is. beyond that there's not much to create problems.if that doesn't yield anything I will try to blow it out backwards with a compressor.I cringe to think of digging up the middle coupling, though I'm guessing that would be the next step, as it's 6' down with a drain line passing over it in the vicinity.Roy
Does it have a separate shutoff valve at the manafold?If so I would check that. It could either have a bad (loose) washer or a something floating in the line behind the valve.Or even if it does not have a shut off, the the connection on the manafold is at the bottom or in some other position that a blockage would always go to that same tap.
Edited 11/18/2004 12:13 pm ET by Bill Hartmann
Maybe you just have a lot of air in the system.
no, it wasn't air. ... and the good news is that I found an accessible elbow that I had forgotten about where the line came up next to a floor drain sump in the outbuilding. I pulled the elbow off (barbed fitting with hose clamps), shined a flashlight down the pipe, went & got my needlenose pliers and pulled out a stick just smaller than the pipe and about 10" long!My guess is that it was part of a stick jammed in the far end of the pipe to defend it from dirt, etc. when it was laid as part of the slab pour rough-in. (I wasn't around for that). When I saw that stick in there, it was one of those shining moments where a great weight of impending doom lifts in a second. The rest of the day was cake.Thanks for the thoughts and suggestions.Roy
O frabjous day! Callooh! Callay!
prezackly!
The last 2 posts- is that from Pogo?400' is a long way to go with 1" pipe. The inside of the plastic may be smooth to you, but friction causes turbulance in the water flow and restricts volume. Just like air in ducts. You want laminar flow and if the pipe is too small, roughness at the joints or has tight bends, your volume will suffer.
"I cut this piece four times and it's still too short."
I think the first was from the Jabberwocky? "Caloo Calay - it's frabjes day?"Les Barrett Quality Construction
Unc Dunc sounded pretty pogoid to me and - being a huge pogophile - my response was intended that way.... now there's a topic for appreciation & praise !!Roy
Can't wait till the holidays so I can sing "Deck us all with Boston Charlie".
"I cut this piece four times and it's still too short."
Have you ever considered that when you have a actual inside pipe size of 1" and then you insert a coupling or elbow into it that now, this so-called 1" pipe is now 'choked ' down to approx 5/8", depending on the thickness of these fittings.??
Think about it.
yeah, I do wonder about choking the flow down at internal fittings. it seems to make a fair difference in PEX supply lines which I regularly run and which deliver less water than the equivalent copper size, even though it is "smoother" with less fittings.On the other hand, you look at water coming through faucets and other end-of-run fixtures and it sometimes comes through seriously tiny cross-sections at various points. Yet a fair bit of water is delivered. I'd love to better understand the relative effects of all these factors.In this case there is very ample water delivery to this building through the 1" poly line, though I can't say the same thing for another building that is tied into this well and is maybe 50' higher and 750' away. That one will probably get it's own well soon.Roy