Plumber says I need a non-bladder well tank? Why? I want a bladder tank.

Dear Clean Water Man:

My old galvanized well tank has finally worn out and has leaks.  I want a new bladder type tank, but my plumber says that it needs to be replaced with a non bladder tank with something called an Air Volume Control.  I have researched and everyone says the bladder type tanks are better.  Could you stop by and give me a price on a new bladder tank?

Lee, Redding, CT


Dear Lee:

You have an exceptional plumber.  I came out and inspected the old well tank and did some checking, and your plumber is correct, you do need a NON-bladder type well tank.

When your home was built, it was built on ledge or bedrock.  When the well line (the horizontal pipe that connects your well to your house) was installed, the surrounding bedrock made it difficult to bury it below the frost line.  In lovely New England, this could cause the well line to freeze in winter, so a bleed back system was installed.  The bleed back system consists of a specially designed check valve that has a threaded hole on the well side and a threaded hole on the tank side.  The check is in between the holes.  The check allows the water to flow from the well but not back to the well.  Here are the Flowmatic check valves I use, now made of lead free brass.

On the well side (the back end of the arrow) we install a snifter valve. 

 These pictures are not to scale.  On the tank side, we install a plug.  Back at the well, there is a small flapper valve on the pump pipe (the vertical pipe that goes from the pump to the pitless adapter) near the top of your well.  After the pump has cycled and filled the well tank and the pressure switch on your system turns the pump off, the snifter and the small flapper valve work with each other to allow air into the well line and allow the water out.  This helps prevent a freezing well line.

So now we get to the point of why you need the non-bladder tank.  When the pump cycles again, the little flapper valve near the top of the well closes and the air that has entered the line is forced into the home and into the well tank, the current well tank, and the new one your plumber will be installing and this air is why an air volume control is needed.

 

This is the USG Air Volume Control I use.  Notice the white plastic float.  When the float falls due excess air built up in the tank, it opens yet another tiny valve that allows that air to escape.  When the water level rises and lifts the float, this little valve closes, keeping water from spilling on the floor.   If this set up is attempted with a bladder tank, there is no way to vent the air out and it builds up to a point where it comes out in spurts and makes the plumbing act in violent strange ways, like air exploding into the toilet tanks or out of faucet spouts.

Not every old fashioned non-bladder tank was installed for this reason.  There are many old galvanized tanks, some older than fifty years, still functioning.  There was a time when things were built to last.  Woe to the plumber that has to change out a tank that has lasted fifty or more years because it was made with heavy gauge steel and has a half century of crud built up in the bottom and has an enormous mass.  Someone will be going home with a sore back that day.





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