sump pump check valve question

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Old 12-14-02, 12:02 PM
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sump pump check valve question

to anyone with sump pump expertise:

Here's my situation.

I've got a submersible sump pump with a check valve installed above it in the discharge line. the pump works fine but 2 times, the valve was somehow stuck in the closed position even with the pump pushing water up to it. any idea what could have caused this? the first time, i caught it in time and was able to undo the valve and by pushing a screwdriver up into it, open it (allowing a 4' column of water to come rushing out onto my arm and part of the floor). the second time, i hadn't been down to the basement in a day or two after a heavy rain, and of course, there was an inch and a half of water flooding a good quarter of the basement (ruining a rug and whatever else was on the floor nearby...)

since that episode, i moved the check valve up (from about 4 inches above the floorline to about 4 feet and just before the turn out through the wall). my reason for doing this was that i imagined that the 3-4 foot column of water was too great a downward pressure on the valve, even with the pump pushing upward, keeping it closed. your thoughts on this hypothesis are needed...

in the meantime, it's been raining again 3 of the last 4 days and the water is high in the sump-hole. i keep going down to the basement to check that the valve is allowing water to pass at it's new height. so far so good. when i trip the float switch, the water pumps out, just as it should. i'd like to have a system that gives me a little peace however, not like now where i'm worried everytime i see clouds in the sky.

another idea, do i even need the check valve? the outlet pipe goes into a drywell (no idea how old or what condition it's in) so there's only that length of pipe (3-4 feet @ 1.5" diameter) that's going to backflow into my sump-hole and most of it is doing that now since the check valve is nearly at the top of it anyway... so, what are the drawbacks/dangers/inconveniences of not having a check valve in the system???

sorry this is so lengthy but with the history and all, i just wanted to get it all across. if you've made it this far, thanks. if you've got answers to any of the questions i've posed, thanks all the more...

austinpm1
 
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Old 12-14-02, 12:35 PM
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A sump pump by code requires the check valve, with out it, you will overwork the sump pump, shortening it's life span.

Why not just install a new check valve.
 
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Old 12-14-02, 12:52 PM
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the check valve is only 3 years old. is that normally how long they last? until this fall, we've been in a drought here in NJ for 2 of the last 3 summers so i can probably count on one hand the number of times the pump has even been running under natural rainfall conditions during the valve's life.

any thoughts on my placement of the valve higher in the line? i don't have a problem getting a new valve since i think it was only a 4 dollar part and 10 minute job but i just want to have it in the right place and working in the correct manner so that i don't get anymore surprises like the 1.5 inches of water like last time...

thanks for your time-
austinpm1
 
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Old 12-14-02, 12:57 PM
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The check valve is there to keep the pump from turning on too often, install the new one just above the lid line.
 
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Old 12-14-02, 01:11 PM
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where is the "lid line"?
 
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Old 12-14-02, 01:15 PM
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The floor line.
 
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Old 12-14-02, 01:38 PM
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You should drill a 3/16" hole in the discharge pipe somewhere in the discharge line betwee the pump and check valve, with this hole angled so that it sprays / drains water back into the sump.
The reason for this hole is to allow the discharge pipe to drain itself while the pump is not running and not pulling a vacuum on the check valve. When the pump kicks on, it has a easier time lifting the check valve due to the water rising fairly fast when it engages the check.
You will find several sump pump manufactures require this modification to discharge lines for warrenty coverage.
 
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Old 12-14-02, 01:40 PM
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ok then, this kind of leads me back to one of my original questions...

the pipe above the check valve, if it is a the lid line or floor line, is about 4 feet high and then it makes a 90 degree bend and goes out through the wall. the 4 feet of water that just sits on top of the check valve seems to me to be keeping the valve shut just by the weight of it on top of the rubber flap inside the valve. this is why i moved the valve up to almost the very top of the line, just before the 90 degree turn outside, where only about 3 inches of water remains sitting on top of the valve when it's shut.

so, have you ever heard of a check valve not opening because too much water was pushing down on it from above?

again, this is just my theory that the downward water pressure is greater than the upward water pressure when the pump is running, creating a closed system...

i know its a cheap and easy repair but should i be replacing a check valve every 3 years or less???

austinpm1
 
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Old 12-14-02, 01:56 PM
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>

that makes sense to me. if that gap between the pump and the check is full of water, it pulls down like a straw with your thumb over the end, right?

and if that gap is full of air, the water has a few empty inches to gain momentum as its pushing upward to burst through the closed valve, right?

am i getting it?

austinpm
 
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Old 12-14-02, 06:38 PM
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Just leave the check valve where it is if it is working fine... yes the downward pressure of the water could be what is holding it down, but there is really very little head pressure from a 4' head of water... Your pump should not have trouble pushing past that... the proper place for the check valve is closer to the floor but the only purpose is to keep the pump from cycling, so 4' up isn't going to hurt anything... if it were, say, 20 feet high the pump might pump the basin empty, and then when it cut off, the whole 20' of water would go back into the pump and cause it to come right back on and it would just keep doing that over and over and would wear the pump out unnecessarily,... so at 4' you just aren't making that much of a difference...
 
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Old 12-14-02, 08:29 PM
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no ragnar, you're right. with just the 4' head of water, the pump clears out 7" of water down to 3" of water in the sump-hole and when the 4' of water in the pipe falls back down, i can't even see the level rise from that 3" down in the hole.

since the water does fall back down, is it creating a vacuum pulling down on the valve flap anymore? how do i know that the water is indeed falling back down for sure? and that begs the next question, if i've got only a few inches of water below the check valve as others have said i should with the valve being installed at floor level, then why wouldn't the water fall back down from that height too?
 
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Old 12-14-02, 08:45 PM
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hehe, that was the most confusing line of reasoning i have ever been a party to... however, i would say you have the right idea...

But let's just be clear on something... when the pump kicks on it pumps water through the check valve and up to the elbow and then it gravity drains off from there... The check valve is designed to keep it from cycling as I have said before, secondly if the main sewer backs up, you dont want it getting into the sump pump because it would again create a cycling situation... which is also why the basin should be individually vented all the way up to the attic atleast... Anyway... the water below the check valve generally flows back into the basin as most pumps have a device for allowing the water back into the basin so it doesnt just sit against the pump... some just have the hole in the outlet as someone mentioned that keeps water from sitting in the pipe against the pump... in either case, you dont really get the vacuum that HOLDs the check valve down... that generally wont happen over that short a distance of 2" pipe... (does the water stay in a cup if you turn it upside down just because one side is closed?)... Anyway, so the point is, the check valve DOES serve a purpose, and if your pumping system works better with the check valve higher, then so be it... leave it where it is as long as the pump doesnt constantly cycle... and by the way, even if that pipe were full of water and there was a vacuum holding the check valve flap closed, the forces causing it would be INSTANTLY overridden when the pump kicked on as it would have a significantly higher amount of pressure than the downward pressure of water which would be less than a pound of pressure...
 
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Old 12-14-02, 10:31 PM
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sump pump check valve question

The 4' of water above the check valve will put 1.73 psi of pressure on your check valve. If your pump can't open that, there's a problem with the pump.
Notuboo probably has the answer to your original problem. There should be a hole in the discharge line just below the check valve. If this hole becomes plugged up, the pump will "air lock" and will not pump. The hole acts as an air bleed.
Moving the check valve has alleviated your problem (at least for now) but I would suggest that you leave the check valve in place.
Best regards,
Ron Peeks
R.L. Peeks Pump Sales
www.peekspump.com
 
 

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