The mechanical room would be the central spot for electrical, water, and ventilation.
For the electrical I was installing a 12" x 12" electrical box. All of the cables would terminate here. I pulled back the original cables so I have a direct run to the breaker box in the garage.
On the other side of the room is the water. I installed a PEX manifold that will distribute the water, both hot and cold, to the various faucets. Using a manifold like this means I can shut off any one water line at the source. The manifold receives the cold water and passes it through to the water heater. From the water heater the hot water goes into the manifold and is distributed to the faucets.
One reason I needed to mount the water heater is to properly position the propane line when I run it. Also the water heater needed a vent out of the roof. Because of it's positioning the run is only about 3 feet.
High efficiency on demand water heaters can generate a lot of water as a by-product. In order to deal with this I built a drain into the floor under the water manifold and water heater. I made this out of wood and sealed it using Flex-Seal. This way if there is ever a leak it will be contained and there is someplace for the condensate to drain.
The last item in the mechinical room is the ventaliation fan. I used a variable speed fan ducted to 3 vents in the bathroom. It is mounted half way up the wall and vents out the roof. Because I didn't use a standard bathroom fan I only needed to run power to one place, not 3. Also the fan is more powerful than standard bathroom fans and there is NO noise when it runs.
Because the fan is on a switch that I can control from Home Assistant that means that in the future I can put in a humidity sensor in the bathroom and turn on the fan automatically when heeded.
With everything mounted and ready to go it was time to start the installation of the propane.