Every hot water heater I've seen has a regulating knob somewhere. Look for it,possibly under a cover.
Thermostat
If you are using water and not steam there should be a temperature controller mounted in the side of the boiler, that is where the start and stop point of the boiler is controlled.
There has to be a way to turn down the temperature somewhere on your water heater. There is either a dial on a manual control or up and down arrows on an eletronic one.
By locating the thermostat and turning it down
turn breaker off. unhook thermostat wire to furnace turn breaker on. worth a try; if it works you will have to turn off breaker to shut it down.
Replace it or turn your Hot Water tank temperature down
tune up your furnace, turn down the water heater and don't leave lights on when you exit a room.
Salt lowers the boiling temperature of the water allowing to turn down the heat source
For children, 120 f is recommended.
Yes you can do that. I had an oil fired furnace that also heated the hot water in a coil inside the furnace. I got an electric hot water heater and had a plumber disconnect the coil in the furnace and hook up the electric hot water heater. No problems after four years.
The unique feature of water in response to temperature changes is known as the anomalous expansion of water. When heated, ice and water first contract till the temperature exceeds 4 degrees Celsius at which point expansion starts.
water