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Gas Water Heater Problems: Troubleshooting Gas Water Heaters

Gas Water Heater Problems: Troubleshooting Gas Water Heaters

Though gas water heaters are generally dependable, they may develop some problems over time. Read on for some helpful tips on troubleshooting some common problems in gas water heaters.
Saurabha Palekar
Last Updated: Apr 23, 2018
Gas water heaters are a better option than electric water heaters, primarily because of their reduced usage cost. Although natural gas - along with other fossil fuels - has become a very precious commodity, the relatively infrequent and low usage of gas in water heaters means they score above their electric rivals.

Gas water heaters may not work properly because of several reasons. Although qualified technicians are best suited for the job, several repairs can easily be done on your own.

Fixing common problems in gas water heaters is actually quite easy. More often than not, it's just putting everything where it should be.

If that does not work, at times replacing the faulty component is the solution. Diagnosing the problem is usually quite easy, too. Due to the mechanical nature of gas water heaters, the symptoms are clearly evident even when they are not major issues.

Do not ignore any signs of unusual function of the water heater. If not remedied in time, small problems can blow up into something much more serious.
Gas Water Heaters Troubleshooting Guide
Common Problems
Heater does not heat the water
Probably the most fundamental and obvious complaint about a water heater, this has an equally fundamental solution. If the water heater is not producing hot water, it can be due to a malfunction in the
  • Thermostat: The thermostat in water heaters is a thermoelectric device known as thermocouple, and is made up of a strip of two metals. It checks the temperature of the flame from a pilot burner, and shuts off the gas supply if the temperature is not sufficient to ignite it. A faulty thermocouple could cause the gas supply remaining shut off despite the heaters being in perfect condition.
  • Pilot burner: The flame from the pilot burner is directed onto the thermocouple, thus enabling it to gauge the temperature of the flame. Insufficient heat from the pilot burner could cause the thermostat to keep the gas supply shut off.

If the pilot burner and the thermostat are positioned in a way such that the flame does not reach the thermostat at full intensity, reposition the assembly accordingly. Ensure that both of these components are free from sediment or grime. If it is obvious which component is at fault (for example, if the pilot burner does not light at all), replace it. Otherwise, get a pro to make his diagnosis. Some heaters have closed thermostat chambers. If you have a heater with one of these, don't try to repair them yourself, and call a pro right away.
Heater works inefficiently
Incomplete burning operation and improper ventilation cause problems in air combustion, which can hinder the heater's function. Various depositions in the heater, usually due to hard water or dust, affect the heating capacity of the heater. Removing these depositions can solve the problem. If the heater still doesn't work, your pilot burner-thermocouple pairing may be at fault.

Ensure that the thermostat is set at the correct temperature, and not a few degrees colder than usual.

Check if the heater is equipped to heat the amount of water you need. If it is under-equipped, it may result in the water being lukewarm. If so, reduce the water flow.

Check if the gas supply is blocked in some way. Gas water heaters need optimum supply of gas at all times. If the gas line is blocked, remove the blockage. If there is even the tiniest gas leakage, replace the gas line immediately.

Check that the hot and cold water lines are not crossing at some point. If so, get a plumber to properly separate them.
Heater produces noise while heating
Deposition and consequent accumulation of insoluble scale in the tank can result in a popping noise when the heater is in operation. Flushing the tank should take care of the problem. If some noise is coming from a tank-less heater, call a pro immediately.
Water from the heater stinks
Some water heaters use magnesium rod for heating the water. When these rods react to the bacteria present in the water, they produce hydrogen sulfide, which has a characteristic smell of rotten eggs. Clean the tank with chlorine bleach (preferably flush afterwards). If the problem persists, change the rods to zinc.
Leakage from the heater tank
This is a terminal problem, and can only be solved by replacing the heater. But if you are baulked by the price, do consult a pro before making the decision to trash it, but don't go for some quick-fix.
Heater produces rust-colored water
Corrosion due to electrochemical reactions inside the tank can result in rusty-colored water. In some cases, it also indicates that the anode heating rod needs to be changed. Like in the case of the 'rotten eggs smell', change the anode rods to ones made of zinc.
Leakage from the pressure release valve
High temperatures of water can cause this problem. It can be resolved by turning down the thermostat. At times, it also indicates valve failure; in that case, you need to replace the valve.
Pilot light of the heater does not stay lit
Ensure that the pilot burner is covered properly, since a gust of wind can extinguish it.

In many cases, this problem is thermocouple related. This problem may arise if the thermocouple in the thermostat assembly is displaced due to some reason. It can be solved by adjusting its position, or replacing it.
CAUTION: Do NOT keep a heater running while making ANY repairs. Disconnect the gas supply if possible. If you smell gas at any time except momentarily when removing the gas line, make sure the gas supply is properly turned off. If the smell persists, call your gas utility at once.

Replace and repair the parts of the water heater with caution. Make sure that the pilot control valve of the heater is turned off before you start repairing. Secure the water supply to the heater and drain the heater. Always refer to the user manual for troubleshooting tips, it can solve the problem more often than not. If you think the problem is too difficult to handle, or some operation too risky, it probably is. Consult a pro in such cases.
Although gas water heaters are common devices, accidents involving gas can go horribly wrong in a moment. Do not ignore early signs of a problem. Be safe!