One of the problems with the house was the hot water. The water heater was located in the garage and the copper hot water pipe went all around the house attached to the steel "I" beam to where the bathrooms and kitchen are. This caused the hot water to take about 15 minutes to get hot as it had to heat up not only the copper pipe but the "I" beam as well. The previous owner had tried to correct this problem by installing a recirculating pump on the water heater tank and having a one way valve at the upstairs bathroom sink that allowed hot water to be pumped through the hot water pipe to the other side of the house and back to the water heater via the cold water pipe. As you can guess this created a problem of the cold water pipe now being filled with hot water. Also this wasted propane as it is continually having to heat the water.
To correct the problem we decided to make a mechanical room located upstairs above the master bathroom and behind the upstairs bathroom.
I abandoned the hot water pipe and installed a PEX manifold in the mechanical room. From the manifold there is a cold water supply to a high efficiency on demand water heater. This water heater feeds the hot side of the manifold which has a single run to each water faucet. The longest run is about 15 feet. Now we have hot water is when we want it now and when we aren't using hot water we aren't using propane.
As a side note the original water heater in the garage quit working after about a month of owning the house. I still needed it to heat the water for the hydronic heating so I replaced it with a on demand water heater and that has cut down the propane use a lot.