Water Heater Not Making Enough Hot Water

A hand turning up a tankless water heater temperature

BanksPhotos/Getty Images

Like any other appliance in your home, your water heater can cause problems ranging from a lack of hot water to noise, odors, and leaks. One of the major issues you might run into is not having enough water. Here are some factors to keep in mind when repairing this issue.

Not Enough Hot Water

There are several reasons for not having enough hot water; it could be due to equipment problems with the water heater itself, or it could be some change in the environment. Let's start with the simple possibilities first.

  • If you have recently upgraded your tub to a larger one, or if it is a spa type tub, a larger demand on the water heater will cause the water temperature to drop.
  • If you have recently changed your showerheads to a higher flow model, that would also cause you to run out of hot water faster.
  • If your faucet is a long distance from the water heater, the water traveling a long way to the faucet head you may experience a drop in the volume of hot water.

Outside Factors

There are also some factors from outside your home that could cause your hot water volume to be reduced. The most common cause would be the outside air temperature. If your local area is experiencing an unusual bout of cold weather, the water coming into the water heater will take longer to heat. As a result, you may feel that you are not getting the same volume of hot water. If the water pressure into your home has changed, the cold water coming into your water heater may not be enough to force the hot water through your pipes at the same rate.

Thermostat Issues

One of the equipment issues could be a thermostat that is set too low for the size of the water heater itself. The most common setting for the temperature on the water heater is between 120 – 140 degrees Fahrenheit. If your thermostat were set lower, you would notice a lower volume of hot water. You may also have a water heater tank size that is too small for the demand. If you have a larger home with multiple bathrooms, you may need to increase the size of the water heater you are using.

You may also have a faulty thermostat; if that were the case, you would notice a lower volume of hot water. The thermostat is usually set at the factory and is not meant to be adjusted, but sometimes it needs to be changed. If you find that this is necessary, access the thermostat, which is typically hidden behind an access panel, and adjust the temperature as needed.

The thermostat could also be faulty, in which case it may need to be replaced. You may want to contact a plumber instead of attempting to replace it yourself. However, if you choose to replace it, these are the steps to follow:

  1. To replace the heating element, turn the power off at your circuit breaker and remove the cover plates to expose the element.
  2. Verify that the power is off by testing the electrical connections with a non-contact voltage detector.
  3. Drain the water from the tank.
  4. Use a heating element wrench and a long Phillips head screwdriver to unscrew and
  5. remove the old element.
  6. Install the new one and tighten it with the wrench.

Internal Problems

There may also be issues with the water heater internally, such as a bad dip tube. The dip tube is used to force the incoming cold water to the bottom of the tank to be heated. The cold water being heated forces the hot water up to the top of the water heater and into the hot water supply pipes. If the dip tube becomes disconnected or broken, the water in the tank would become diluted and appear as though you are getting less hot water out of the water heater.

Water Heater Replacement

If you choose to replace the water heater with one that is more appropriate for your needs, the basic instructions are as follows:

  1. Shut off the water supply to the water heater, also shut off the electrical power, if you have an electric water heater, or the gas supply if you have a gas water heater.
  2. Drain the water out of the water heater tank by opening the valve at the bottom of the tank near the floor. It may be helpful to attach a garden hose to the drain valve and run it to a nearby drain to avoid a big mess. Once the tank is empty, you can disconnect the gas line, flue pipe and water lines for a gas water heater, or the power wires and water lines for an electric water heater.
  3. Once the area is prepared, you can set the new unit in place, and begin reconnection of the water lines, the gas or electric supply and the flue pipe for the gas water heater. Make certain in the case of a gas water heater that you check your gas line joints with soap bubbles for gas leaks.
  4. Turn the gas/power on, and begin refilling the water tank. For the gas water heater, you must also remember to light the pilot light. You also want to make sure that the thermostat is set to the temperature that you want, the most common setting is 120 degrees Fahrenheit. At this point, your new water heater should be set to go.