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Frozen Water Heater Troubleshooting And Repair Guide




Is my water heater frozen? It’s a cold winter morning, and you have woken up to discover no hot water coming from any faucets in your home.

You can’t be blamed in most cases for thinking the water heater has frozen but it probably hasn’t. In most cases just a pipe leading in or out of the water heater will be the problem and not the heater itself. The heater will have heat supplied either by its burner or, elements, which will prevent the tank from freezing. Even if the water heater stopped heating it would take quite a while for the insulated tank to cool down enough to freeze. It might happen after a long power outage or, if the house was vacated in the winter and the utilities were shut off without the home being properly winterized.

While either the pipe going in or, out of the water heater may freeze, especially if it is exposed to a cold draft many times the lines containing heated water may freeze before lines right along side them carrying cold water. This phenomenon is known as the “Mpemba Effect” which was discovered by a Tanzanian high school student Erasto Mpemba in 1963.


When troubleshooting a frozen water heater you will need to trace the pipes in and out of the water heater until you locate the area where it has frozen. Once you locate the frozen area apply heat carefully using a space heater, hair dryer or, heat gun, with a faucet open until the water starts to run again. When water freezes it expands which depending on where it freezes and in what order it freezes can exert a force in the area of 40,000-psi which can split virtually any material used in plumbing if it cannot expand enough to absorb that force without breaking. It is critical that you take action at the first sign of a frozen pipe to have a chance at avoiding damage.

Some of the things you should do when attempting to thaw frozen pipes is to turn up the heat. Many people may have thermostats set at a reduced setting to save energy, or, may have unused rooms turned down low to save energy. When you have frozen pipes it is time to turn up the heat in an effort to get the pipes warm and thawed. Open up areas where pipes run so the heat can get to them. If you have pipes in storerooms, closets, and cabinets, open the doors so the heat can get in there. If you have metal pipes you may be able to find a plumber that has an electric pipe-thawing machine. Electric pipe-thawing machines send a low voltage, high amperage electric current through the metal pipe, which can rapidly thaw the pipe. You don’t even need to know where it is frozen, all you need to do is clamp the cables on the pipe with the frozen spot between the clamps.

Once the pipes have been thawed and the water is flowing again you need to check carefully to make sure that none of the pipes have burst from the freezing and are now leaking. The pipes will not leak while they are frozen but as soon as they thaw will immediately leak if they have burst. Make sure that you know where to shut the water off to stop the flow beforehand.


After successfully thawing the pipes you will want to ensure that the pipes will not freeze again. The best solution really depends on the specifics of where the pipe froze. Sometimes blocking the path of the draft, and insulating will prevent future problems. Other times insulating the pipes will delay the effects of cold from reaching the pipes long enough that they will not freeze. Often electric heat tape such as Frostex can be installed which will keep the pipe warm enough to prevent freezing again.

A frozen water heater is something you want to avoid at any cost but it will only happen in a sustained outage with no heat and no energy supplied to the water heater. If you are experiencing an outage and a sufficient amount of time has gone by that the water heater is in danger of freezing you should shut of the electric and or, gas to the water heater and drain the water heater to prevent the tank from rupturing from the expansion of the water freezing. You should be able to drain the tank by shutting off the water supply to the water heater, opening the drain valve at the bottom of the tank, and then opening a hot faucet or the T&P valve to allow air to enter the tank so the water can flow out of the tank. This down and dirty draining of the water heater will save the water heater but you probably still face damage to the pipes from the effects of freezing. Having the water shut off to the home and opening everything up will possibly save some things from the effects of freezing. In an outage caused by a blizzard or, ice storm there is little chance of a proper winterization being done.

When a property is going to be vacated through the winter season and the utilities are being cut off the best option is to make sure that the property is winterized before the cold season or, as soon as it is vacated before the utilities are cut off. Weatherizing is not a precise science with a home that has not been designed for weatherizing such as a seasonal home. Even weatherized there still may be freeze damage but it should be less then it would be if weatherizing were not done. If you have allowed a frozen water heater to occur the best thing you can do is disconnect the water heater and get it outside before it thaws. This will prevent the ice from thawing in the home and leaking out of a ruptured water heater. There is no way a water heater can freeze and be used to produce hot water again.