my house is on a gravity fed system from a creek and i just tried to splice into the tube but instead of water shooting out of the new pipe, its sucking air hard. my original line is 1.25 inches and i attached a 1.25 T- joint to it with some pipe and then turned it with a 90 degree attachment 4 inches later and then reduced it to 1" and then 3/4." the old pipe has great water pressure and the new pipe is cocked at a slight angle so that is sits slightly below the old pipe. any ideas on how to get water flow into the new pipe?
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Alaska
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Re: gravity water system sucking air
Sat, July 5, 2008 - 6:15 AMYou can't have a 90 off of the main pipe . the water moving down draws air from the second line. this is the very old school way to get a vacume. you have to use a 'Y' connector, or an upside down "Y ", I should say.
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Re: gravity water system sucking air
Sat, July 5, 2008 - 6:28 AMDan is correct. You have created what is called a Venturi effect.
At any rate I'd not tap into the line like that . I'd prefer to let the water accumulate in a plenum before tapping off any water.
A plenum would allow you to accumulate a body of fluid in a larger tank which will equalize the pressure any given line gets when it's opened up.
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Re: gravity water system sucking air
Sat, July 5, 2008 - 9:50 PMthanks for responding so quickly. a plenum is not possible. i'm using black poly pipe so the only kind of joint they offer is the T. Unfortunately, there are no Y's unless I can use those white pvc joints. do you know if you can mix pvc joints with poly tubing? or do you know of any type of valve that would only let water flow out and not let air suck in? thanks for all help. -
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Re: gravity water system sucking air
Sun, July 6, 2008 - 6:19 AMThere are check valves, but that won't fix the problem.the water won't be "pushed" into the branch.
You can combine pvc and poly with the right glue. However there may be a slight size varence, preventing a good seal.
there are poly "y's" out there, check in the lawn watering systems, section of the big box hardware stores.
You can switch the T around. so that it looks like an upside down T , rather than a sideways T, same as you would use the Y. with the water comming in the top and going out 90 deg. in either direction. You may however get less water presure do to the turbulance it the point that the water slams int the 90 deg turn.
Another alt. is to use a multi valve adapter made to screw on to the outside spiket. They make Y's and 4 ways. Each branch has a shut off valve. this would involve fitting water hose type screw on ends, not a big deal. I would go with the 4 way for future expansion possabilities. Like being able to just screw on a standard water hose. Big / Odd Lots, has a good supply of hose fittings both plastic and brass, for a long term use, go with the brass.
If you want to maintain better pressure whils using multi lines , you can add a larger section of pipe just above the joint ( at least 4 ') this gives you a plenum of sorts by alowing a greater volume of water to collect above the restriction, thus providing greater pressure. Sort of like Obama's election $$$$ vs. Mccains $ -
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Re: gravity water system sucking air
Sun, July 6, 2008 - 10:10 AMInteresting.
Expanding on Dan's 4" pipe idea with a few more details.
This idea is dependent on your ability to attach pvc via screw on "hose type" fittings to pvc (should be able to find the fittings online if no where else).
Get a section of 4" pipe (maybe schedule 80 pvc?).
This may not be cheap, but I think it will give you a "plenum of sorts". Purchasing it will mean getting a full length, whatever that comes in - maybe 10' (maybe you can hook up with a shop that works with this stuff and get a scrap piece for $5). Cut it to whatever length works for you - maybe as little as a couple feet (but why not take advantage of the full length). Glue a bushing at each end (not sure what these cost, but I'm sure they are not cheap either). At the top, fit the busing with a pvc pipe that is the right size for the connection you will use to screw on your poly. Place a Y into the bottom bushing (glue or screw) and attach to your two poly lines with screw-on hose type connections.
Apply plenty of teflon tape to threads.
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