There are other skills plumbers need aside from being able to work with water. One of the most common things that a bathtub replace on is fixing water lines.
The wax ring is used to seal the drain outlet on the bottom of the toilet to the drain opening in the floor. When a toilet is installed, the ring is placed onto the drain... the toilet is dropped onto the ring... and the toilet bolts (also known as closet bolts) are tightened enough to lock the toilet in place. If that wax gasket ring starts to fail or isn't seated properly? Sewer gasses can sneak out from under your toilet causing your bathroom to have that suspicious smell. It can also cause water line repair to escape, sometimes invisibly, with each flush potentially damaging the floor hidden under the toilet.
There may be more pipes in your home than you think. Your home gets all the water it needs, either from a municipal water connection or from a well, through one central pipe, which branches out and distributes water to all the other places in your home that need it. These pipes run under your floors and sometimes through your walls. Most of the time, they take care of themselves and you never need to think about them.
Once you have disconnected the tank remove it from your work space. Do a thorough measurement of the remaining pipe for reference when you go to the hardware store. I will be honest with you, you might need to make a few trips back to the store. Once you get the new tank, slide it into place to line up the plumbing.
The first step in the replacement project is to turn off the water line repair to the toilet and flush any water that may be in the tank. If you forget this step, you will have a giant mess to clean up! You should now disconnect that water line.
For a newly installed icemaker, you will need up to 24 hours to let the machine function and cool down. A newly installed icemaker may not work until the ice mold temperature has dropped to about 15F - 16F degrees. If you have just added a water line to the refrigerator, it may take up to about an hour and a half for the machine to start working. Also, a newly installed water line may have air in the line. It can sometimes take a few ice making cycles to clear the line of air.
The plumber you hire does not normally do heating but will do hot water heating or in floor heating in the house. Some places you can use the water heater for both domestic hot water and for in floor heating if the heating is a secondary heat. Check with your local plumbing codes on this to be clear.