Normally open check valve?

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pcthiker

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I have a pipe from my dehumidifier joining a 3/4" pipe that is usually dry but can have flow when it rains. I am trying to prevent backflow from the main pipe up to the dehumidifier when the water in the main pipe gets going. Doing a little research I went looking for a normally open check valve since I wont get any pressure from the dehumidifier for 3/4" pvc pipe, but I can't seem to find it. Is there another product or other phrases I should be searching for? THanks in advance for any suggestions!
 
Just raise up the dehumidifier on some wood or patio blocks.

Water does not run uphill.
 
Thanks for the thought. That was my initial logic. The water has to go up a 36" to reach the dehumidifier but seems to do so.
 
If the water is “flowing” uphill, then there is a blockage or restriction downstream in the shared drain.

It is really being “pushed” uphill.

In that case, the normal flow by gravity is blocked, or can’t keep up with the influx during rain.

What is the source of the rain drainage water?

Is it a sump pump discharge?

Any kind of pumped discharge can of course flow uphill, and it will seek the easiest route.

You need to describe this whole system end to end, in much more detail.
 
First question I have, is: Why does the line you are draining to have water when it rains?

Second, Can you post some pictures? Most of the check valves without springs are slanting disc valves, but they typically need to mount horizontally. And, the ones with springs need a couple of psi to open. Which would be about five feet of water column.

I’m pretty sure that you could install an air relief, air admittance valve and that would work, but be spendy. This should work: Plastic Air Release Valves
 
I have a pipe from my dehumidifier joining a 3/4" pipe that is usually dry but can have flow when it rains. I am trying to prevent backflow from the main pipe up to the dehumidifier when the water in the main pipe gets going. Doing a little research I went looking for a normally open check valve since I wont get any pressure from the dehumidifier for 3/4" pvc pipe, but I can't seem to find it. Is there another product or other phrases I should be searching for? THanks in advance for any suggestions!
it is illegal to join 2 indirect drains they must be run [instlled] independently
 
If you are joining a dehumidifier drain, to a house drain system, it must be done with an air gap. Just search for "air gap" on Amazon, and you'll find suitable ones. I took the drains from the a/c, furnace, and dehumidifier and put them all into an air gap and trap before putting into the house drain system.

That being said, if you have some kind of flow that backs up in your pipe, then you may have other issues.
 
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