Sometimes it seems like the sump pump has it out for people. It will never go bad at 11 am on a Saturday when you are just sitting around. It will go out in the middle of a storm, 11pm on a Sunday. However, changing a sump pump is not as difficult as you would think.
It seems like there are as many choices in sump pumps as there is ham at the deli counter. You should match your pump with the application. How big is your sump pit, what is the vertical height the pump has to push the water, and how many gallons per minute do you expect the unit to pump?
Now you could do all the figuring called for above or just go out and buy a 1/2 hp pump if your vertical lift is 10' or less (measured from the basement floor to the exit through the wall) and your basement footprint is 1500 sq ft or less.
Unplug the pump and secure the cord so it does not fall into the pit. Draw a line with a marker on the bottom pipe right below the check-valve. Loosen the hose clamp/s on the bottom of the check-valve, letting it slide down the pipe. The check-valve only lets water flow in one direction (look for the arrow) and in this instance that would be up. If you loosen the top connection all the water in the pipe above will drain downward and all over you. Slide the pump one way or the other while gently pulling the check-valve towards your body. You may have to insert a screwdriver up between the pipe and the rubber of the check-valve to loosen it before pulling.
Once you have the pipe and valve separated, lift the pump out of the pit and set it on a couple towels so it can drain. Remove the new pump from the box and review the instructions that came with it. Place the new pump next to the existing one and note if the outlet, where the pipe attached is the same height. If it is the same height then you simply unscrew the pipe from the old pump and attach it to the new pump.
If they are different heights you need to make a new pipe. If the difference is less than A�' it will probably still work, providing you will have at least 1' of pipe into the check-valve. Use the mark you placed on the pipe under the valve to measure from. Measure from the floor to the top of the pipe and write the measurement down. Using the same diameter pipe as you have now, attach a new pipe to the new sump pump using the measurement you took off the old pump. I suggest using PVC pipe because it is so easy to work with.
After you have the pipe installed secure the cords to it using wire ties or electrical tape. Slide the hose clamp over the new pipe and let it slide down. Place the pump into the pit, tipping it slightly slide the pipe into the check valve. Slide the hose clamp up and secure the check-valve. Stand back and make sure your pipes are straight, if not slide the pump over a little. Secure the remaining cord and plug it in. If the pump does not turn on and there is water in the pit you can manually turn the pump on by lifting the float if you have that style. If not you will need to fill the pit using some buckets or run a hose into the pit until the water level activates the pump switch. The last thing after checking for leaks is to replace the lid.
Remember to file the papers that came with the pump, and send in any warranty information. You are now protected for many years to come, unless there is a power outage, but that is another article.