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Thread: Air Ejector Control

  1. #1
    DIY Junior Member BrianP's Avatar
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    Default Air Ejector Control

    I have a galvanized steel tank which has an air ejector control valve on it. No bladder as the pump makes air. The pressure switch for the pump was set at 30-50. Whenver the pressure got near 30 the air ejector valve opened up and bled off excess air. I understand the valve works on water level. The pump turned on and filled up the tank.

    I just had to replace a leaking check valve between the tank and the supply line. While they were here they also replaced the switch (old one over 20 years old) and new pressure gauge. The new pressure switch is set at 40-60The air injector valve never seems to bled of any air now.

    Questions:

    Since the air ejector works based on water level, I'm assuming the change in pressure switch settings has nothing to do with it not bleeding air? The contactor said that the fact the valve opened up just before the pump switched on most times was just a consequence.

    Since the tank had to be completely emptied to replace the check valve am I correct that when the tank first fills up it has more water than air? If that is correct that would explain why the water level is too high to trigger the air ejector.

    Is it a fair statement than to say that the air injector valve only needs to function when the water level drops below the valve and not everytime the tank refills?

  2. #2
    Moderator valveman's Avatar
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    Quote Originally Posted by BrianP View Post
    Is it a fair statement than to say that the air injector valve only needs to function when the water level drops below the valve and not everytime the tank refills?
    Yes, the air volume control has a float inside the tank. Float drops, air comes out.

    Also the check valve that was replaced is a very important part of the air charge. I hope they replaced it with one that has a Schrader valve, like on a car tire, on the inlet side, and removed the little cap. That is where the air gets in.

  3. #3
    DIY Junior Member BrianP's Avatar
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    No it looks like a standard check valve. They said the pump makes air when it turns on before the water starts flowing and that is sufficient for the tank.

  4. #4
    Moderator valveman's Avatar
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    If that is not a "control check valve" with a hole for a Schrader valve, then it won't let air in. The pump does not make air, it comes in through the Schrader valve when the pump shuts off.

  5. #5
    DIY Junior Member BrianP's Avatar
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    Maybe I'm describing this wrong to you. When the pressure switch turns on after a few seconds you can hear air going into the tank creating a bubbling sound. Water than starts to flow and the bubbling noise stops. Isn't that the air entering the tank? The system I have is very old. The pump itself is at least 30 years old. The contractor said he didn't think there was a check valve on the pump side.

  6. #6
    Moderator valveman's Avatar
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    You are describing it fine. There still has to be a place up top for the air to get in. Otherwise it is like holding your finger over a straw full of water. Unless there is a leak somewhere, the water is held by a vacuum and no air can get in. Not having a check valve is the pump means the air is probably entering at the bleeder orifice, which is not the way it should work, and is way more air than you need.

  7. #7
    Test, Don't Guess! cacher_chick's Avatar
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    Not all systems use a schrader valve. Around here it was common to have 2 bleeders in the drop pipe, one spaced about 18" over the other. This causes a measured amount of air to enter the tank each time the pump starts.

    It's not unheard of for the float valve in the pressure tank to fail. More often than not when the valve fails it leaks water. I use a non-contact thermometer to measure how high the water level is in the pressure tank. (there will be a notable temperature difference between the water and air portions of the tank). The water level should be near the level of port for the float valve when conditions are normal. If the valve is stuck closed the tank will in time fill with air and eventually you will get air out the faucets. You could alternatively measure your draw-down to see if the pump is cycling too often.

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