How does a drain back valve / Bleeder Orifice work on a foot valve water pump system which might have air leaks?

[Greggunningham]

I have cistern which is filled either by truck or pumped from the lake. To connect to the cabin, there is a pipe with a foot valve at the bottom, and a pump with a pressure tank at the bottom of the cabin.

My setup is a bit different since we don't have a basement, and the pump is closer to ground level so there is around a 5 foot (1.5 m) height difference between the foot valve/bottom of the cistern to the pump.

In the current setup the foot valve works perfectly, you prime the pump at the start of the season, and it doesn't lose prime. I want a valve which at I can open without going into the cistern to drain the water at the end of the season.

The problem that I am trying to solve is during winterization of the cabin. We can drain all the lines inside using compressed air, but to drain the suction line (from the pump to the foot valve), we remove the foot valve so it all drains. Is there a better way of doing this?

I looked up how it's done with submersible pumps, and it appears that there is a snifter valve paired with a drain back valve (also called water outlet, "bleeder valve" or "Bleeder Orifice". There are two versions:

Copper (with a ball):

>As a pump turns on and builds water pressure, the orifice is forced closed with a ball. When the pump shuts off, pressure drops and the orifice is opened, allowing water above the orifice to drain out.


There is also a rubber version:

>Provides fast water bleed capacity through its large orifice opening when pump shuts off
>Orifice completely closes when the pump is running and prevents loss of pumping volume


How do these work and would they work in my case?

From the sub pump version, I believe they need a Snifter Valve which allows air into the line.

My understanding, in theory in my case, if my plumbing is air tight, when the water pump stops and the tank is pressurized, not much water would drain back out of the drain back valve.

In practice, when I installed the foot valve with a small gap (I didn't warm the pipe up before putting in the barb), it was leaking and the pump would lose prime every 3 minutes (since air might be entering from a joint in the buried pipe?). I'm afraid if I installed this drain back valve, I would have the same problem potentially as I might have an air leak somewhere.

Are there other alternatives? One idea is a pressure blow off valve right after the foot valve. This way I could add a string line and pull it open to drain.

The other ideas I have seen is connecting a fishing wire to the foot valve so you can pull it open from outside but it seems sketchy. This is explained in this video:

but the idea is he glues the foot valve nut to a washer with a hole which is connected to a fishing line:

The other idea is a ball valve which is spring return ball valve which is normally closed and doesn't have a too tight spring. This also seems unideal as it will be submerged.

 

[LLigetfa]

You cannot use a bleeder with an above ground pump with foot valve. They only work with submersibles.

 

[Sponsor]

 

[Reach4]

You could put a submersible pump into the cistern. A drain back valve is not going to work with a suction pump.

With a suction pump, I could envision a tube/pipe teed to the foot valve. The tube would have a valve accessible from the surface. When doing your winterizing, you would insert air and open the valve.

You would want that tube to be part of your sanitizing procedure, maybe annually.

Another idea would be to tee the foot valve to a pressure relief valve. So when you compress to 75 psi, the relief opens to let out water and/or air.

 

[LLigetfa]

One idea is a pressure blow off valve right after the foot valve. This way I could add a string line and pull it open to drain.

You could use a standard pressure relief valve without a pull string. You just need to supply air pressure that is higher than the pop-off pressure.

 

[Greggunningham]

You could put a submersible pump into the cistern. A drain back valve is not going to work with a suction pump.

Thanks! That seems like a much more expensive option and I have a couple of extra jet pumps sitting around the house. But that's a good solution!

With a suction pump, I could envision a tube/pipe teed to the foot valve. The tube would have a valve accessible from the surface. When doing your winterizing, you would insert air and open the valve.

This is a cool idea! This way once you add compressed air, you can visually see all of the water spray out and the line would be drained.

You would want that tube to be part of your sanitizing procedure, maybe annually.

What did you mean by sanitizing procedure? At the moment, all we do is add cholorine to the water in the cistern once we pump it from the lake, and then run a 50 and 5 micro filter. This year I might add a UV filter.

Another idea would be to tee the foot valve to a pressure relief valve. So when you compress to 75 psi, the relief opens to let out water and/or air.

Interesting. I'm in Canada and most of the pressure relief valves are for air compressors rated at 125 PSI. It also seems like the orifices are tiny (>.25"). Do you have a link to a product sold in the US or Canada which would work here?

 

[Reach4]

1/2 hp 10 hp pumps are not so expensive. The pump would sit horizontally and be in a flow inducer sleeve.

With that tube and valve system, you would open the valve while the pipe is pressurized and let chlorinated water slowly fill the tube and sit there. When the pressure is up and the pump is on, that pipe is pressurized.

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[Valveman]

In your case I think you could use a bleeder orifice. You would just need to install it very close to the foot valve. When the pump is drawing water it will also draw through the bleeder, so you want it below the water so it doesn't suck air. But when you turn off the breaker to the pump and open a faucet, the lack of pressure in the system will still let the bleeder open and it should drain from the open faucet all the way to the water surface in the cistern. Haven't done it. But looks like it would work.