doing extensive remodeling of a small (1400 sq ft) house. I want to move the electric water heater to an old shower cove. Getting the wiring there will be easy (its about 5 feet away and all the walls are currently open).
I would use the old shower cold water pipe to supply the water heater and use the old shower hot water pipe to supply the rest of the house from the water heater. Those connections would be simple to do.
I realize the 1/2" shower lines are smaller than recommended for a water heater, however at the old water heater site the 3/4" output line is immediately reduced to 1/2" BEFORE any branches – so the entire house is currently being served by 1/2' trunk lines. The street supply to the water heater in its current location is 3/4', so that would be a significant change in the new location.
It seems to me that, physics being a constant, if the output trunk is 1/2", then having a 3/4" supply to the water heater doesn't matter, since the water can't come in faster than its going out. Therefore, there should be no change to the pressure or flow rate throughout the house with the water heater relocated to the old shower.
Finally, the new (old shower) location will have a floor drain (concrete slab, single story house) so that's a plus for the relocation of the water heater.
My question : is there anything I'm missing about connecting the old shower pipes to a water heater?
I will throw in here that putting in an electric tankless heater in the current water heater's location is an option, but I am not thrilled with that plan – tankless electric water heaters seem to be less powerful than their gas fired cousins.
Best Answer
You can move the water heater to just about anywhere that would be convenient. However, it is not a good idea to reduce the size down from 3/4" to 1/2" directly off of the tank. You will likely run into issues with water pressure.
In branch plumbing, it is best to keep the size of the pipe at its maximum until it branches off to a specific fixture. Most fixtures, with the exception of a toilet takes 1/2". A toilet is actually reduced to 5/8" by the time it gets to the fill valve. 5/8" is an odd size in plumbing, so most plumbers typically run 1/2" anyway.
You should try to extend the 3/4" pipe as far as you can go, and then tee off of it using multiple 3/4 x 3/4 x 1/2 tees. When you tee off, try to make that run directly to a fixture without teeing off again. This will greatly help keep the water pressure balanced. If all of the plumbing is 1/2", then the fixtures will compete against each other for water because there is not enough volume of water coming through the pipe.