# Air Volume Control



## elrodalonzo (Nov 15, 2011)

I have a shallow well (12 ft) with a GE 1/3 hp shallow well pump hooked to a 42 gallon epoxy lined (bladderless I think) water tank.  It gets full of water and I have to almost completely drain it and then refill it frequently or else the pump comes on with any demand for water. What kind on AVC do I need and how do I hook it up?  My tank has the inlet on the bottom, half way up is an old inoperative AVC, above that is a Schrader valve and on the top of the tank is a plug.  I see Granger makes an AVC with a float on it but I don't know where to put it on the tank or how to hook it to the pump.  Also should I put a gauge somewhere on the tank?  There's an old rusty gauge in the line before the tank and it reads 25lbs.  Any help on this matter would be appreciated.  Thanks.


----------



## joecaption (Nov 16, 2011)

That's one very shallow well, I'd be more inclined to be looking at the suction line from the pump all the way down into the well. It there even one pin hole in it, or loose connection there will be air in that line.
Also are you 100 % sure the foot valve down in the well is always below water and also not sitting on the bottom?
If you were to buy a bladder tank the pump would stop coming on every time you draw water.


----------



## elrodalonzo (Nov 16, 2011)

It's a hand driven well and I had trouble years ago with the copper pipe that went inside the 1 1/2 inch well casing.  It developed a small hole and we lost prime.  We just hooked the suction line to the top of the well casing and it's worked fine since then.  Is the mistake I made buying a bladderless tank?  Maybe I should just drain it down and pump some air pressure in it.  If so how much? Should I put a gauge on the top? thanks.


----------



## joecaption (Nov 16, 2011)

I personaly and my plumber agee's I would have used a bladder or diaphram tank instead of just a storage tank. It's common to see a pump come mounted to a storage tank which is fine but every time the taps opened it turns the pump on and will wear out the pump and contacts far sooner.
Your tank is suppost to have some air at the top of it to act as a cushion to stop water hammer but to often I've seen them become water logged.
He's some info on how they work.
http://www.watersystemscouncil.org/VAiWebDocs/WSCDocs/9884303Sizing_a_Pressure_Tank_FINAL.pdf
If it was a bladder or diphram pump there would have been a gauge on the tank and an air valve to add air. It's set to within 2 to 5 PSI of what the pump pressure is. I would not add air to your tank. You can however drain the tank and refill it which shoud give you the air space back.


----------



## Blue Jay (Nov 16, 2011)

Air volume controls are fine when they work and yes you can add air thru the schrader valve, that is what it is there for. Been a long time since I have had a bladderless tank, so working on memory here with the water at a low level inflate the tank to 5lbs less than the pressure switch cut in point (even the bladder tanks have this precharge in them). Don't see a need to put a gauge on the tank itself as your existing gauge will work fine but if it is real old might want to replace it so you are sure of pressure you are working with.

  Also I would put the suck line back inside the casing as the way you have it hooked you are drawing a vacume on it and could pull contamination into the water.


----------



## elrodalonzo (Nov 16, 2011)

Thanks Blue Jay,
  I think I'll draw down some water in the tank and pump some air in there.  My pump is quite old so when that dies someday I think I'll put on a new pump and get a tank with a bladder in it.  As far as running the draw line back down the casing I'm a little afraid to undo it now I had fits getting things primed and working last time.  We don't really use the water for drinking anyway since it's so shallow and in our basement.  We live in an old river valley and these hand driven wells are a very common set up here. Thanks for your help.


----------



## comalapaul (Jul 10, 2013)

I have been installing water pressure systems here in Mexico. When the tank sits on the water source, I put an auxiliary tank in the source line. When the tank reaches the maximum pressure and the pressure control switch shuts the pump off, the aux. tank drains back into the source. Your check valve will prevent the water in your pressure tank from retuning to the source.(you will need a small hole in the pipe just ahead of the submersible pump.) The aux. tank supplies an excess of air, and the float valve (Wayne 15901-WYN1) will bleed off the excess air at the one third level of the tank. (measure 1/3 down from the top) I use 1000 liter tanks purchased from the scrape yard. A 5000 liter tank (plastic) is suitable for a family of 6. Extract the water for your pressure system from this tank.


----------



## Speedbump (Jul 11, 2013)

Air controls are a thing of the past.  I have a couple dozen of them collecting dust at my shop.  They work best if the pump pulls hard on the well, because the vacuum has to pull a diaphragm back against a spring.  No vacuum to speak of, no air.

I agree with everyone else, a bladder tank is the best thing.  And there are good ones and bad ones.  With your galvanized tank, you can hook a compressor to the schrader valve and push the water out of the tank.  Once air spits out of the faucet, (this is done with the pump motor off) close it and put about 20 lbs of just air pressure in the tank.  Now turn the pump back on.  You will see an amazing difference in the time it takes to come back on again.  This can be done when necessary.   The whole reason for this is to prevent the motor from cycling any more than necessary.  Cycling a motor wears them out.


----------

