Water Heater Leaking and How to Fix it

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How to repair water heater leaking from the drain valve, top and bottom of the tank and pressure relief valve. How to check and find common leakage points. Troubleshooting, causes, prevention and DIY repair tips.

Since the leaking water heater is a very common problem in both gas and electrical heating systems, the first thing you should do before buying one is to consider a location for its installation, so the potential leak won't damage the property.

Tips for fixing a water heater leak

The first sign of the heater leak is a puddle of water at the bottom of the unit. The good thing is if the water is dripping, the bad is if it is spraying or flooding. Two of the most common spots where the water drips from are the pressure relief valve (TPR or T&P valve) located at the top of the unit or drain valve, found at the bottom.

As said, spraying or flooding are bad as there might be a pipe burst, corroded tank, broken valves so water can exit the tank in a short time and make a damage. You can find more info here on how drain valve and
TPR valves work and how to replace if damaged.

Heating units should not be installed in the location where leaky water heater may result in property damage. One of the solutions might be installation of the drain pan, water leak detector and shut off device. Sensors are used to trigger the alarm or to turn off the incoming cold water when leaking problem is detected.

The drain pane should be installed at the same time as the water heater so it can catch potential drip from the pressure relief valve or loose connections. From the drip pane and through the installed pipe, water is removed to the drain.

If the water is found under the tank of the electric unit, you might want to check the gaskets on the heating elements. The insulation needs to be removed in the area of the electric elements to indicate a drip.

Condensation can also be considered as a leak, because of the amount of water and suddenness when it occurs. It usually disappears when the heater becomes warmer. The excessive condensation occurs during the colder months, winter and early spring. It usually affects the gas-powered heaters.

Leakage points

  • When water is heated in gas heaters and due to its hardness, minerals are separated and attached to the hot surface. During heating these surfaces become hotter affecting metal tank. Prevention is a key - flush the tank regularly at least twice a year, or install the softener.

  • When hard water is heated in electric heaters, sediments are forming, so heating elements can become very hot and break, and water heater leaks. Solution is in regular maintenance, softener installation or in installing heating elements resistant to failure due to lime buildup.

  • There is quite amount of vapor in flue gases and it usually condenses on the vent pipe and draft hood on the top of the tank. When combustion products cool, the moisture becomes liquid, known as carbonic acid that attacks the metal. To solve this problem, you can install a heater properly sized so there is no rapid drop in temperature when it is used. Another solution is to install a mixing valve to reduce cold water impact.

  • Plumbing pipes are also condensing, so insulate them also.

  • If plumbing is leaking find the leak and fix it.

  • Anode rod fitting may cause leaky water heater. Inspect the metal anode rod regularly as it prevents internal corrosion. During the time and because of the water action, the sacrificing rod dissolves slowly.

  • Due to the thermal expansion or high pressure in plumbing, the TPR valve tends to leak or open. Excessive pressure in the tank causes failure of joints, welds and gaskets. Adding an expansion tank it limits the pressure to near incoming pressure. TPR valve also limits pressure to factory set max.

  • TPR valve fitting might cause water heater leak - replace or reseal it.

  • If drain valve is slightly open tighten the drain valve.

  • Water is too hot - when stored at 160 F (72 C) is twice as corrosive as when at 140 F (60 C).

  • During the start-up condensation - it takes usually 1-2 h before it disappears.

  • Improperly sealed connections, TPR valve, drain valve, relief valve and thermostat connection.

  • Contaminated air and chemical vapors from household cleaners might come in contact with a burning flame or electric contact, creating various acids that can attack metal tank and corrode. Solution is to provide cleaner, chemical-free room or to purchase a direct vent heater that uses air from outside.

Note: Puddle of water is not always coming from the water heater. You might have leakage from other appliances or plumbing line. Do not replace the heater unless you did a full inspection and took corrective action like tighten treaded connections, replace broken parts. You might be able to fix the leak before scrapping it.

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