Water from a water heater that is too hot or not hot enough may be the result of a broken thermostat or heating element, but it can also be caused by an incorrect setting. The factory temperature for water heaters is 120 degrees Fahrenheit, but this may be too hot or not hot enough for some users.
Inspect the thermostat, which controls hot water heater temperature. If someone has recently changed the setting, that could be the reason behind your lukewarm water woes. However, if the temperature setting is correct, the thermostat itself might be broken. You can have the thermostat replaced fairly inexpensively.
Sediment buildup in the tank
While the water sits in and is heated by your water heater, this debris settles to the bottom of the tank. Many water heater burners are on the bottom of the tank. So, this buildup of debris can make your water heater less effective at heating your water, leading to lukewarm water.
The three most common culprits are sediment build up, a faulty heating element and a broken dip tube.
Check the circuit breaker.
If you have an electric water heater, the first thing to check when experiencing hot water issues is your circuit breaker. A tripped circuit means the current was disrupted. As a safety measure, the circuit breaker flips.
Sediment build up in the tank
Over time, sediment can build up in the bottom of the tank, where the burner usually is. This can lead to slower heating or poor efficiency in your water heater, meaning lukewarm water rather than hot water. The solution for this is to drain the tank and to use a water softener.
Broken Internal Heating Element
Consistently lukewarm water can be caused by a problem with the upper heating elements. If you have a short-lived supply of hot water, it could indicate a problem with the lower heating elements.
Sediment and Scale Buildup Inside the Water Heater
The inside of tank-type heaters can corrode and, eventually, this corrosion settles to the bottom of the tank. However, sometimes the pieces of sediment get drawn into the hot water supply line and will create a blockage which lowers water pressure.
The water heater tank size is too small for your household. Your hot water heater is tankless. Sediment or minerals have built up in your water heating system. Individual parts inside the hot water heater unit are damaged or worn.
Most homeowners should flush their water heaters every 6 months or so, but if you have extremely hard water, you may want to do it more often. Flushing your hot water heater could be necessary as often as every few months depending on the mineral content of your local water supply.
However, if either thermostat fails to turn off, the reset button will trip to prevent the tank from overheating. Other common issues include a burnt-out heating element, a worn-out reset button, or a faulty circuit breaker or wiring.
Your shower mixing valve controls the water temperature of your shower by blending together cold and hot water. Sometimes, though these valves wear out, break, or are positioned incorrectly and that can cause uncomfortable shower temperatures.
Water heaters show several signs of going bad, including lack of hot water, temperature fluctuations, decreased water pressure, strange noises, rotten egg smell, visible leaks, rusty or discolored water, and increased energy bills. If your water heater is over 10 years old, it may be time to consider a replacement.
To test the element, you must measure its resistance. Switch the multimeter settings to measure resistance and place the nodes on the two screws. A functioning heating element should read between 10 and 30 ohms. The heating element is broken if the meter reads 1 or 0.
A thermostat for a hot water cylinder is generally fitted to the body of the tank by a strap or band. This allows some degree of flexibility in the vertical positioning of the thermostat. The typical location is around one third of the way up the cylinder.
Thermostat Replacement
Each heating element has its thermostat; if those don't work, the elements won't either. Hiring a pro to replace a thermostat averages around $150 to $200. The part itself costs up to $20 and is easily replaceable without disturbing other components if you have some DIY experience.
A lack of hot water can be caused by a variety of issues. In electric water heaters, a power loss or heating element failure can cause water to no longer heat in the tank. In gas water heaters, a faulty gas connection, a bad pilot light, or a bad burner can cause no water to heat.
Put one probe from the multimeter on the reset terminal (beside the reset button) and the other probe on the left side terminal, which will be the one with power wires. If the multimeter's reading says 1, then the water heater thermostat most likely needs to be replaced. If it reads 0, it is functioning normally.
As the particles collect on the bottom of the tank, the water heater can't effectively heat your water, resulting in lukewarm water only. To resolve this issue, open the drain valve on your water heater and see if there is sediment. The water will not be clear if there is sediment build-up.
The pilot light on most water heaters can be found at the base of the unit just under the gas control valve. Open the access door or panel to the burner chamber and take a look inside. You should be able to see the pilot light tube. If there's a steady blue flame, your pilot light is operational.