Here, where i live, we have a water shortage.
Also, saving on energy is important, when there are a lot of people living in one house. Taking a bath, when 9 others want to bath too, lets electricity bills rocket to the moon.
So, here is a short intractable for instant hot water for as long as you shower and built entirely from old household appliances.
Step 1: Collect the Parts
i fix appliances for a living, so it was readily available in my house.
You will need the outer drum of a Washing machine.(any kind and size,as long as it can hold water)
A pressure switch with rubber diaphragm. Its usually around 40mm in diameter. From a dishwasher.
An inline heating element from a dishwasher.
A cheap ball valve to regulate the level of water in the drum.
Some pvc pipe and fittings to lay out the plumbing.
Dishwasher pumpmotor(optional for more pressure)
Some plumbing knowledge and electrical knowledge.
WARNING. BE CAREFUL WHEN WORKING WITH WATER AND ELECTRICITY IN THE SAME PLACE. YOU WILL SHOCK.
Step 2: Assembly Is Easy
start by knowing where you want to put the unit. Usually outside the bathroom, close to the existing plumbing.
Build a stand that will keep the tank(drum) securely. As high as you want, to ensure a strong flow of water.
The pressure switch should be as close to the drum as possible. I used a t- connection by the drum outlet. The T - side to the side so the switch activates when the water pressure releases the diaphragm.
Step 3: Connect the Plumbing
Routing the plumbing depends on how the area looks like where youre building the shower, but make sure of the order. From the drum, add the pressure switch, element, pump motor(optional).
Make sure that you install the element as close to the entrance to the wall where you connect to house plumbing and make it lay diagonally. This makes it heat up the water better than a straight downward flow.
So, looking at your setup, you should have something like this order: Drum.pressure switch.element.pump.connection to house plumbing.
Step 4: Connect the Wiring.
start by connecting the element and pump motor in series. Then from the motor, break the live by connecting it to the pressure switch. Once the weight of the water releases of the diaphragm, when you open the tap, it will activate pump and element.
When tap closes, the power goes out and the drum Will fill up to where you set the ball valve.
So, there you started saving electricity, using less water and having a refreshing shower. And all from old appliances. My build cost me about $40 when converted from ZAR.
I have trouble adding photos of actual project, but the images you see, are of the important things.
Im also planning to cut out the house water supply to the shower and adding it to my current build of a rain water harvesting tank.
Ps, you're welcome to add your own improvements. As long as you save save save.