How to Replace an Element

TECHNICAL SERVICE DEPARTMENT
Technical Service Bulletin
1-800-432-8373
How to Replace an Electrical Heating Element
Technical Competence, Product Confidence
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If you are not comfortable working with electricity, do not attempt this procedure. Call your plumbing
professional. If you are working on a Marathon Water Heater, the water in the tank must be cool
before you drain the unit. Failure to cool the water may result in the polybutylene inner tank to
collapse or deform. After shutting off the electric circuit breaker, allow the water to run from a hot
water faucet till cool. You will also need to use a 1 7/8 inch socket to remove the elements.
Be sure to use the same element flange, gasket type, wattage, and voltage as on the element being
replaced.
1. Before servicing the water heater, DISCONNECT or TURN OFF
the main electric power breaker
feeding the water heater. This is normally located in the electric service panel.
2. Remove the cover panel and insulation to expose the heating element. Remove the plastic protective
cover over the thermostat and heating element.
3. Before servicing the heating element, verify with a voltmeter, that voltage/power has been
disconnected to the water heater. Measure for voltage at the top two screws of the thermostat. There
should not be any power.
4. Shut off cold water supply to the heater. Lift and open temperature and pressure relief valve to vent
pressure. Open a nearby hot water faucet. Connect a garden hose to the drain valve at the bottom of the
heater and open the drain valve. Drain water to a point below the element that you are replacing.
5. Disconnect the two wire leads to the heating element. You do not need to tag the leads before removal
from the screw terminals.
6. Remove element using 1-1/2" socket for screw-in type, or 3/8" socket for four-bolt type.
7. Ensure surfaces of new coupling flange and new element flanges are clean. With a new heating element
gasket in place, install the heating element. Snug it down tight.
8. Reconnect the two wire leads. It does not matter which color wire goes on which screw terminal.
9. Close the temperature and pressure relief valve. Open the shut off valve at the cold water inlet line.
You will hear the heater start to fill. Shut off the faucet (that you opened in step 4) only after getting a
constant flow of water, without air, from the faucet. Failure to properly fill tank can result in element
damage.
10. Double check to be sure your wire connections are correct and they are firm and tight. Check for leaks
around the heating element. Tighten more if needed.
11. Replace the plastic protective cover to the thermostat and heating element.
12. Re-establish the electric power to the water heater. Cycle test the water heater to be certain of proper
operation.
13. Replace the insulation and cover panel.