Help with a bleedback system

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Hi Guys im trying to completely understand my sytem, i have a wellmate pentair HP system which has the avc in it. its a bleed back system. when i had my plumber install it several years ago he put it in with a shrader valve on the top. for refrence here is the installation instructions.
heres my issue the insructions say that you should have a plug installed or a snifter valve installed on the top of the avc. im wondering if my plumber had done it completely wrong and thats why im having issues with my tank. they informed me that they need to bring th pressure up to 12 psi then add the water however in the instructions they say the opposite i should add water to the tank first and when the barbed npt fitting stops pushing out air i should fill the tank to the cut off psi manually after. secondly since its a bleed back system i have a snifter before my check valve so the water can bleed back obviously, however messing with it today i noticed that while the valve does allow air to go back into the well pipe to the house it is not letting it completely bleed back as when i press on the snifter stem after it has stoped sucking air it will suck air again for like 2 minutes. why would my valve not be completely drainging the pipe back. please help this is killing me to try to wrap my head around it.


DIYer, not in the trades
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NW Ontario, Canada
There are several components required for it to work correctly. First off, the snifter is different from a conventional tire valve in that it has a weaker spring that requires less suction for it to open. You might need to replace it with one that opens more easily. How much pipe is between the snifter and bleeder determines how much air gets pushed to the HP tank on each pump cycle.

Second, you need a bleeder that will open even with some pressure against it. The pressure may vary depending on the elevation difference between the snifter and the bleeder. Some systems are designed with two bleeders, one higher than the other which acts like a snifter letting air in. Do note that the bleeder is held open by a spring which is opposite to a snifter which is held closed by a spring. On a system with two bleeders, since the bleeder is held open by spring pressure, the top bleeder will let some air out and maybe spit out some water before the flow overpowers the spring to close it.

Lastly, there has to be an AVC to remove excess air which I assume your HP tank has. The AVC needs to be able to vent so you cannot put a snifter on it. Do note that the AVC bleeds off air very slowly and that it might not be able to bleed a large volume of air fast enough.

P.S. some drainback systems use other means than a bleeder to drain the pipe. These might be a hole drilled in the pipe or the poppet in the check valve, or might simply remove the poppet entirely. There are considerations and drawbacks which each method.
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