Gas Water Heater Not Maintaining Temperature

It’s the 21st century, and we want our hot water to stay hot and the cold tap water to be cool. Unfortunately, that is not always possible, even with the latest water heating technology. 

Your gas water heater might fail to maintain temperature, in case your unit is undersized, the gas burner is faulty, and the dip tube is damaged. New gas valves, shower cartridges, and pressure-balancing valves should be able to fix the problem.

Why Does My Gas Hot Water Keep Going Cold?

This might happen, if you have an undersized unit or if there is something wrong with the gas supply.

Such a problem is especially common in instant gas hot water systems. Here’s what might be the issue in such a case:

  • An undersized gas bottle
  • A faulty restrictor or showerhead – these components can affect the tap’s ability to register as ‘a tap with hot water’
  • A faulty gas meter diaphragm 

Read: Why Gas Hot Water Heater Is Not Heating? – Troubleshooting Guide

Why Does My Gas Water Heater Not Stay Hot?

Check other gas appliances in the house to figure out, if there is a problem with the gas supply.

After that, touch the temperature-pressure relief valve on the water heater and the outlet pipe (it’s usually located above the unit).

If the components feel warm, then it looks like the water heater is working perfectly fine, but the hot water is getting blocked somewhere in the system. If either the valve or the outlet pipe is cold, then there is an issue with the actual water heater.

In the majority of cases, you will be dealing with a pilot light that keeps going out. This can be because of a faulty gas valve or thermocouple or no gas supply.

Read: Gas Water Heater Thermocouple Possible Issues

Why Is My Water Not Consistently Hot?

  • The water heater’s tank size is insufficient
  • The demand on your unit is too high
  • The gas burner is dirty or faulty
  • You have old gas valves that are unable to keep the water temperatures consistent

Why Does My Hot Water Temperature Fluctuate?

If you are sure that the tank is of the right size and that the demand for hot water in your house has not increased, then you can try checking the gas burner.

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The flame at the burner should be blue. If it’s yellow, then the flame will fail to heat up the water effectively.

Ideally, you would want to call a professional who is going to clean the burner or replace the component if it’s corroded or cracked.

To go the extra mile, you can get a thermostatic mixing valve. This element is going to blend the hot and cold water; it is also able to sense the water temperature and control it (unlike the older valves that lack a temperature balancing feature). 

Hot Water Heater Sometimes Hot Sometimes Warm

A malfunctioning thermostat might be responsible for any kind of water temperature problem. Try adjusting the setting on the thermostat and if the water heater fails to respond, then you might have to replace the thermostat.

Sediment build-up and a damaged dip tube can also lead to temperature fluctuations. 

Gas Hot Water Goes Hot Then Cold

One of the most common reasons for hot water suddenly going cold is a broken dip tube.

A dip tube sits inside the tank; it connects to the cold-water pipe and runs down the tank. The main job of this component is to push the cold water closer to the base of the tank so that it can get heated. 

If the dip tube is damaged, the cold water will end up at the top of the tank, where it will get mixed with the hot water. As a result, you will start receiving cold water.

In such a case, the only solution is to replace the dip tube and flush the tank

Read: Is Furnace And Water Heater The Same?

Why Does My Water Get Cold So Fast?

If the hot water from your gas water heater goes cold too quickly, then it might be because:

  • The unit is too small for the demand
  • There is sediment build-up in the tank
  • The dip tube is broken
  • The thermostat is faulty
  • The pilot light is going out
  • Your water heater is too old

Hot Water in the Morning but Not at Night

The chances are that the water in your heater gets warmed up during the night and then when you start using it throughout the day, the liquid doesn’t have enough time to heat up again.

Other possible reasons might include:

  1. A leak
  2. A dripping tap
  3. A faulty pressure valve

Read: Why Water Heater Is Leaking?

Propane Water Heater Not Hot Enough

The first thing that you should do is check the thermostat settings. You might have to adjust the temperature, but be careful as water over 120 F can cause scalding.

Also, do check if your tank is large enough for your household. Take the number of people living in the house into consideration and the appliances that need water to function (like a dishwasher, for example).

Finally, make sure that your propane water heater is receiving adequate airflow – the flame needs oxygen to continue burning. The air vents shouldn’t be clogged – you might have to disconnect the pipes on the water heater to check that.

Why Is My Hot Water Extremely Hot?

  • The thermostat is set too high or is broken
  • Sediment build-up (such a mineral layer can cause overheating)
  • The pressure relief valve is blocked and the pressure inside the tank is too high

Why Is My Shower Not Regulating Temperature?

If the water temperature in the shower changes when you flush the toilet or, for example, start the dishwasher, then there might be an issue with your pressure-balancing valve (or you simply don’t have one).

The main job of the valve is to regulate pressure changes, making sure that the water pressure doesn’t run low.

You can also replace the shower cartridge. The element has special holes that regulate the temperature and the water flow; as a result, you will have more precise control over the water that your shower is delivering.

Gas Water Heater Not Maintaining Temperature – What Should I Do?

  1. Adjust the thermostat on the water heater – someone might have bumped into the device by accident.
  2. If the water heater is not responding to the temperature changes, then you might have to replace the thermostat. 
  3. Inspect the unit for leaks – tighten the connections and replace the valves that are leaking.
  4. Flush the water heater, if it has sediment build-up.
  5. You may have to replace the temperature-pressure valve or there can be an issue with the gas control or burner assembly, but you might want to leave that to a professional. 

How Do I Make My Gas Hot Water Heater Hotter?

Simply adjust the temperature settings.

Gas water heaters usually have a single knob that controls the amount of heat that will be directed to the unit. To increase the temperature, turn the knob counterclockwise.

Does Turning Up Water Heater Make Hot Water Last Longer?

The hotter the water, the less of it you are going to need to make cold water warm. In a nutshell, you’ll be using a smaller percentage of hot water for the same water flow.

This, in its turn, will make the hot water in your tank last longer.

Read: The Best Temperature For The Water Heater And Why?

How Long Should a 40 Gallon Water Heater Stay Hot?

If your tank is well-insulated, the water in it should be able to stay hot for a day or two (if you are not using it).

In case your water heater is working correctly, a 40-gallon tank could be providing hot water continuously for around 45-60 minutes.

Gas Water Heater Thermostat Troubleshooting

In the majority of cases, there would be something wrong with your thermostat if the temperature of the water is unstable.

In case the water heater is not adequately responding to the thermostat temperature changes, the chances are high that the device is not calibrated correctly.

Thermostats have two types of calibration:

  1. The actual water temperature (the difference between the water temperature and the thermostat setting should not be greater than +-5 degrees).
  2. The differential of the temperature of the water before the heater turns on (the difference of the temperature of the water at the top and the bottom of the tank; if it’s over 20%, then the thermostat would have to be replaced).

What Is the Most Efficient Temperature for a Hot Water Heater?

Experts recommend setting the temperature to 120 F. Anything below will allow bacteria to develop in the tank, anything above increases the risk of scalding.