Rebuilding a water heater is often a way of extending the life of a tired electric water heater with parts that only cost about $100, and a couple of hours of your time. A sign that your water heater could use rebuilding is frequently running out of hot water when you always had enough before and your usage patterns haven’t changed.
A water heater that appears to be in decent condition without a lot of corrosion at the connections or, leaking is an ideal candidate for rebuilding. Changing out the thermostats and elements will restore the ability to produce a full tank of hot water for your use. Changing out a T&P valve will ensure that the water heater operates safely without building up dangerous temperatures and pressures within the water heater. Changing out the anode rod will help prevent the steel tank from corroding and leaking which would make you have to replace the water heater. If you want, you can opt to troubleshoot the water heater and replace only the components that have actually failed or, have worn or, been consumed. Generally when I’m rebuilding a water heater i replace it all rather than risk returning to replace something later. Of course you are dealing with an old tank still that appears to be in good shape but there is always a possibility the tank could start leaking tomorrow.
How To Drain The Water Heater
The first step when rebuilding the water heater is to empty the tank. Draining the tank is only necessary if you are changing the elements. The T&P valve and anode rod are located at or, near the top of the tank so a partial draining is all that is needed when working on those items. The first thing you need to do in order to drain the tank is to shut off the electrical power to the water heater. If you can run a garden hose from the drain at the base of the tank to a point that is lower than the water heater drain to drain the water you will not need a pump. Even if the hose goes higher than water heater drain as long as the hose end where the water comes out is lower the water heater will drain by siphoning. If the water heater is lower than the drainage point like in a basement installation you will need a pump that hooks up using garden hose connections to drain the water heater. I start the draining process by opening the drain valve allowing water to flow out using the water pressure in the water heater. Once the flow through the hose has been established I shut off the water feeding the water heater and open a hot faucet allowing air to enter the tank so it will continue to drain. Once the tank has drained down below the T&P valve connection I usually prop the T&P open as well. Once the tank has emptied and water stops coming out of the drain you are ready to rebuild the tank.
How To Change Thermostats
The thermostats are located under the two access panels on the side of the water heater. Always ensure that electrical power has been shut off to the water heater before removing the access panels. Electric water heaters in a home are typically powered with 240-volts which poses an electrocution hazard if the panel is removed while power is still applied to the water heater.
Using a screwdriver take the wires off the old upper thermostat keeping track of which ones supply the power from the power panel, supply power from the upper thermostat to the upper element, and supply power to the lower thermostat and element. Once the wires have been disconnected lift the tabs holding the thermostat in place and slide the thermostat up and out of the water heater. Slide the new thermostat into place under the locking tabs. The new thermostat may have slight variations in the terminals used so follow the instructions included with the new thermostat for wire placement on the new thermostat. Make sure that you tighten the terminal screws, loose connections can generate heat and cause the thermostat to burn out.
Once the upper thermostat has been replaced, move down to the lower thermostat and replace that as well. The lower thermostat is a lot easier with only two connections to make up. Make sure that both thermostats maintain physical contact with the tank because the temperature is detected by the thermostat conducting heat from physical contact with the tank. If the metal plate on the back of the thermostat is not touching the metal tank the water will not be heated to the correct temperature and dangerous overheating of the water can occur. Make sure the thermostat is set to a safe temperature in accordance with the plumbing code used in your area.
How To Change The Elements
The elements are also located under the same access panel as the thermostats just below the thermostats. They have two screw terminals for the power connections and in most cases the elements are a 1½” socket size hex head that screws into the tank. Most water heaters use 4500-watt elements and you should get replacement elements that match the ones your water heater uses. There are some water heaters that use lower wattage elements and some places sell 5000-watt elements, but you should not change the element wattage when replacing them. The circuit breaker and wires may not be able to handle the larger power requirements on higher wattage elements and lower power elements will reduce the recovery rate of your water heater.
One thing that you should consider is upgrading the quality of the element you install, at least on the lower element that typically does most of the work and can become buried in mineral sediment causing it to burn out. Elements made out of Incoloy which resists corrosion, are available, as well as low-watt density or, ultra low-watt density elements, which run cooler resisting burnout, yet still deliver the same amount of heat into the water. The lower wattage density elements still have the same wattage but the elements are longer and run cooler resisting burnout. Some ultra low-watt density element manufacturers actually claim their elements will not burn out from sediment buildup and can even be dry fired without burning out.
An inexpensive stamped steel socket is typically sold for replacing water heater elements but I have found they are difficult to use and often slip of the element. I prefer to use a 1½” six point socket and a breaker bar for replacing elements. Disconnect the wires from the element, and then use the socket to unscrew the element from the water heater, and pull it out of the hole. While the lower element is removed you should go in through the hole to remove the sediment from the bottom of the tank. I usually use my wet dry vac and a piece of 1” tubing on the end of the hose to get inside the tank, and get the sediment out. Take the new element and insert it into the tank then get the threads started and tighten with the socket. The weight of the element makes starting the threads difficult, you will have to press the element firmly into the hole to keep it straight when starting the threads. Once the element is tightened connect the wires to the screws and replace the plastic safety cover that goes over the thermostat and elements. Then replace the access covers and secure them.
How To Change The T&P Valve
When replacing the T&P valve on your water heater you should be certain to get a properly sized T&P valve for your water heater. In most residential electric water heaters a Watts 100XL T&P valve will suffice but you need to make sure the T&P you install is adequate. The drain line from the T&P valve will have to be unscrewed from the T&P valve so the T&P can be unscrewed from the tank. In some cases the drain line will have to be cut then rejoined after the T&P is replaced. If the T&P has 2 flat surfaces for a wrench then a large adjustable wrench can be used for removal. If it doesn’t have 2 flat surfaces then use a large pipe wrench for removal. Make sure if the T&P valve is located on the top of the water heater that you have the water heater braced to prevent it from spinning and damaging the pipe and wire connections. Put Teflon tape on the threads then apply Teflon paste over the tape to ensure a leak free connection and thread it into the water heater and tighten making sure the discharge lines up properly and reconnect the discharge pipe.
How to Change The Anode Rod
The anode rod is a sacrificial metal that is consumed typically in about 4 years although it varies with differing water conditions. The anode prevents the steel tank from corroding and replacing the anode when needed can greatly extend the life of your water heater. The anodes supplied as original equipment in water heaters are magnesium although certain water conditions may cause sulfur odors in which case an aluminum or, aluminum-zinc-tin anode should be used. Where there are clearance problems on top of the water heater a segmented or, flexible anode rod can be used. The anode will typically be attached to a plug, which screws into the top of the tank or attached to the bottom of the outlet nipple. On the plug type anode I use a cordless impact wrench and socket to remove and install them. If you use a socket and breaker bar or, are removing the hot outlet nipple using a pipe wrench make sure you brace the water heater to prevent it from spinning and damaging the pipes and electrical connection. Of course if the anode is on the hot outlet the pipe will have to be cut and rejoined as well. When putting the anode back in wrap Teflon tape on the threads and apply Teflon paste over the tape then thread the anode in and tighten.
Refilling The Water Heater
After rebuilding a water heater I close the hot faucet and turn on the water while the tank is full of air allowing the tank to pressurize while the drain is still open allowing the incoming water to blast against the bottom washing any remaining sediment out of the tank. Once the draining water is clear I close the drain and reopen the hot faucet to allow the air out and the tank to fill. Once the water is coming out of the faucet with no air I close the faucet and turn the power back on to start the tank heating.