Replacing a water softener is relatively easy since the plumbing and wiring are already in place. All water softeners hook up the same way. The key is to drain the old water softener so that it doesn't flood the area during the exchange. It is also worth saving the loose salt or potassium chloride nuggets or pellets that are in the old salt storage tank. Just make sure you know if the pellets are salt or potassium chloride.
Unplug the power supply to the existing water softener.
Close the water shut-off valve to the house. It is on the main water pipe.
Set the bypass valve. The bypass valve is at the back of the water softener. It is where the copper pipe meets the water softener pipe. If the bypass valve includes inlet and outlet valves, close the inlet and outlet valves and open the bypass valve. If the bypass valve has one stem, close the plunger into the stem.
Remove any good salt or potassium chloride you want to keep from the old unit. Don't bother with any fused lumps.
Remove the holding clips at the water softener inlet and outlet. Separate the water softener from the copper pipes.
Remove the brine well cover and disconnect the tubing at the nozzle. Remove the brine well valve and tip the brine valve to empty any water.
Move the old water softener to a drain and tip it over. Don't worry about damaging the inlet and outlet fittings if you are going to junk the water softener. Tip the bottom of the water softener until the all of the water drains out. Discard the water softener.
Place the new water softener in position. Reconnect the inlet and outlet clips. Trace the water back and verify that the water supply is going into the inlet and the house pipes are fed from the outlet.
Fill the salt/potassium chloride tank with salt or potassium chloride pellets.
Plug in the power supply.
Open the main house water supply.
Restart the water softener with an initializing sanitary start. Sears Kenmore instructions suggest using a bucket to fill the salt storage tank with 3 gallons of water. Pour a couple of tablespoons of unscented household bleach into the brine well. Set the bypass valve to "Service." Press the "On/Off/Hold" button for three seconds to start a recharge. This will sanitize the water softener, fill the tank to the right water level, get air out of the resin tank and flush chlorine from the system. Your water softener may have slightly different button labels or procedures for initial start up, check your manual for details.