OT: Draining a water pressure tank without a shutoff valve

I've posted this to alt.home.repair, but in case that doesn't work out, I h ope maybe some of you might know.
I'm changing out the water pressure tank, but I don't have a shut off valve from tank to well to drain the tank. If I turn off the breaker to the well pump, will this effectively shut off the water so I can drain the tank and replace it? Help much appreciated.
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On Sat, 2 Aug 2014 11:11:21 -0700 (PDT), Michael

Assuming it's not an artesian well, sure. You'll want to drain the system, below the pressure tank before making too big of a mess. While you're doing this, be sure to add the appropriate valves so you don't have to mess with it again. Use good ball valves (stainless?).
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On 8/2/2014 2:11 PM, Michael wrote:

This was a task that as a child that I got to do regularly as we had to craw under the house to do it.
I assume this is your system: There is a pipe from the well to the pump. The pump puts the water into a storage tank, where pressure is maintained to provide water to the outlets in the house without the pump activating every time a valve is opened.
While it is nice to have a valve on the pressure tank to release the pressure at the tank, you can also relive the pressure by opening a valve in the house and let it run until no water comes out. When the water stops running the pressure on the tank should be near zero.
There should be a valve low in the tank to drain the water from the tank if not you may be able to siphon it using a drain lower than the pressure tank.
If there is no pressure valve, or drain valve on the tank, you may have to drain as much as will come out when you open a valve in the house to remove the pressure. You will then have to remove the tank partially filled wit water. (I would definitely make sure both are on on the new tank.)
You do not want the water of in the tank to drain back into the well, that is a safety design to prevent the well from becoming contaminated. There is a back flush valve between the pump and the well that will prevent the water going back into the well. There may be a double back flush valve, or one only at the foot of the pipe deep within the well.
I can not believe that a pressure system does not have a pressure relief valve, I believe that is another safety issue.
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On Saturday, August 2, 2014 1:11:21 PM UTC-5, Michael wrote:

ll pump, will this effectively shut off the water so I can drain the tank a nd replace it? Help much appreciated.
Many thanks for the replies!
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On Sat, 2 Aug 2014 12:13:42 -0700 (PDT), Michael

Yes, but if you need water elsewhere then take the line feeding the tank, freeze it with CO2 and sweat in a shutoff ball calve so you can work with ease. A utility tool rental company should have a line freezer for rent.
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