Air in water lines
Hi, I have a bleed-back well system so the water can drain from the well supply line back into the well to keep the underground supply line from freezing; in our area of Southcentral Alaska we can get upwards of 10 ft of ground frost. There is a snifter valve (like a tire valve) on the supply line to break the suction so the water can drain back down when the pump's shut off. Originally, we put in a 75 gal pressure tank with a float valve, so the air that builds up in the supply line when the water drains back to the well can be expelled from the pressure tank as the water recharges the supply line. Then the float valve closes, allowing the air to pressurize the water system. 2 yrs ago the original pressure tank sprang a leak. I replaced it with a smaller bladder tank because it would have taken too long to get another tank like the original (I had to leave town the next day). I also added an in-line water filter. At first all worked reasonably well, except when the filter would get dirty, then, for some reason, we'd get air in the line. Lately, though, we've been getting air in the line all the time, even with a clean filter (I don't know what the filter has to do with anything...). The supply line comes out of the bottom of the bladder pressure tank, so I'm not sure why we're getting air in the line; seems like the air would rise to the top of the tank and just have water coming out. I'm worried that my well is going dry, but it's been gurgling along like this for several months without getting worse. A couple of years ago I had to replace the pump but at first I thought the well was going dry, so I lowered a bolt on a string to see where the water level was. Got the damned thing stuck and had to break the string to get it out (minus the bolt) so I don't want to try that trick again. Anybody have an idea of what's going on, and how to fix it? Thank you for help.
Re: Air in water lines
The bladder inside your bladder-tank has a substantial amount of air in it and has no other route of escape other than out the plumbing lines to the house fixtures.
Since you have a bleeder type system on your well, every time the pumps starts.....the air in the line is injected into the pressure tank. The original single compartment galvy tank contolled this via the fact that the air-head and water shared the same compartment (no bladder) and the air-volume control let off the excess air so the tank never became air-logged.
However, this air is now being injected inside the bladder along with the water. The accumulated "extra" air is being forced out the house fixtures as there is no air-water volume control on a bladder type tank to purge it off.
Unfortunately there is no way to easily mount such an air-water volume control on a bladder tank.....and you would be better off in the long haul by installing another galvy tank with this control.
However, you can get rid of this extra air inside the bladder for the time being by turning the pump off and then opening a nearby faucet (or the tank drain valve if one was installed) and completely emptying the tank of all the water(and air) that will come out. Once that's done, close the faucet (or drain valve) and then turn the pump back on. This should remedy the nuisance air in the lines problem....until the "excess" air again accumulates to the point where it is coming out the faucets.
Last edited by goldhiller; 12-30-2008 at 11:36 AM.
Re: Air in water lines
Thanks for the prompt reply; it makes good sense. If I'd have had any sense to begin with I'd have waited to get the proper tank when replacing it. Last night someone told me that an "air admittance/bleeder valve" would allow the air to purge from the well line as the pump was pushing up more water, then shut when water hit it so water wouldn't start shooting out instead of air. Does that sound like it might work until this bladder tank goes out, when I can replace it with the right galvy tank? In the meantime, I'll drain the line of air and water as you suggest.
Thanks again, John