How to Install a Pressure Tank for a Morrison Head System

Your pressure tank has ruptured but since you own an old Morrison head on your well, your plumber has tried to convince you to move to the new advanced system. Instead, install the pressure tank yourself correctly. This connection diagram is not for modern well systems.


  1. Image titled Fp7230_707
    Use a pressure tank without a diaphragm. In this example, the Flotec 42 gallon (159.0 L) epoxy lined water tank FP7230 was used. Use such a tank because the air must come out the top of the tank to purge the line which goes above ground at the Morrison head, preventing it from freezing. One cannot set up a precharged tank according to this diagram. N.B. If a precharged tank is used, the system will not work and the Morrison head will freeze. Please refer to the image.
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    Attach the top of the tank to a tee along the incoming horizontal supply water line. This way, the momentum of the travelling water will help it to continue travelling past this tee whose purpose is to allow air from the top of the tank to pass back to the well. To attach the top of the tank to this tee, install elbows, piping, and a recommended union, plumbed as appropriate for the placement of the installed water supply line and the size of the tank to be used. Do not use a check valve to try to sort the air from the water, it is costly and unnecessary. Two 24" pipe wrenches are necessary to remove the plug at the top of the tank, since it is affixed so well.
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    Next, continue the water supply line by attaching a nipple then an elbow and then continue to the bottom of the tank, through a union. At this point, one may tee to a drain valve or a relief valve. For the FP7230, the relief valve should operate at 75psi with a flow rated at the pump's capacity. No relief valve is shown in this image; the relief valve is only necessary if the pump can supply more than 75 psi.
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    In the middle of the tank, mount the air volume control. In this example there is a Johnson Controls' F93B. Air is constantly pumped into the tank by the Morrison head system, and this air volume control bleeds the excess out of the system. Without this control, the system will work but with much air in the outgoing plumbing. The pressure gauge or pump pressure switch may be mounted on this control using 1/4" NPT. Brass or copper fittings may be used here since the F93B is non-conductive.
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    Continue the house plumbing at the other side of the tank at the bottom.
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    There is one remaining hole in the FP7230 which is a 1/4"NPT connection, one may plug it or attach the pressure switch there, such as in this figure.
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    Leak test and operate the system. If there is a blow-down connection for compressed air as in this diagram, leak test can be done using air and soap bubbles.


  • Always buy more fittings at the store than you think you'll need, because unused fittings can be returned
  • Do not attempt this if you are not strong enough, even with the two 24" pipe wrenches it was quite difficult to get the plug off the top of the tank even though I do this every day


  • This is an advanced-level plumbing project
  • Do not use a precharged tank with a Morrison head
  • Use a fresh air volume control because it is the item with the shortest life span of all these parts
  • Always use a dielectric union when going to or from copper piping
  • Check your local code for information on whether type L or type M piping is necessary in your area

Things You'll Need

  • pressure tank, NOT precharged
  • two 24" pipe wrenches, i.e., monkey wrenches, as well as smaller ones for the smaller fittings
  • elbows, tees, nipples, bushings, unions, dielectric unions, plugs, relief valve, drain valve
  • solder, plumbing paste, torch depending on application

Article Info

Categories: Maintenance and Repair