A water heater is a storage tank with temperature controls and either a gas burner or electric heating elements. The tank is lined with porcelain or plastic to prevent rust. Most units also have a sacrificial anode in the tank; it corrodes over time. Any exposed steel won’t rust as long as a working anode is in place. A pressure relief (t&p) valve lets water and steam escape if pressure builds due to overheating. A high-temperature cutoff shuts the heater down if the water temperature exceeds 190°F.
Drain the tank every 6 to 12 months. This maintains optimal efficiency by removing sediment particles that collect at the bottom. To drain the tank, shut off the cold-water inlet valve. Open a hot-water tap somewhere in the house. Attach a hose to the drain- cock, and let the water run into a suitable drain. To refill the tank, reopen the inlet valve; when the water runs clear, close the draincock and the hot-water tap. Test the pressure relief valve every 6 months by depressing its lever to allow some water to escape. If no water is released, have the heater serviced.
Components:
- Cold water in
- Draft hood
- Baffled flue
- Pressure relief valve
- Overflow pipe
- Anode
- Dip tube
- Burner assembly
- Draincock
- Gas water heater
- Hot water out
- Gas line
Note: Details of repair and disassembly may vary, depending on model. If your heater differs markedly from this one, consult the service manual or a plumbing contractor.
Correcting gas heater problems:
Clean pilot orifice. Shut gas cock (see owner’s manual); remove burner assembly by disconnecting its lines at gas control valve. Gently probe orifice at pilot light with a thin copper wire; don’t use needle or paper clip, which may damage orifice. Vacuum out debris.
Check thermocouple for loose connections at control valve, and verify that its bulb tip is held in pilot flame. (The thermocouple signals a shutdown if pilot flame goes out.) Don’t overtighten nuts; screw them on finger-tight, then give only a quarter turn with an open-end wrench.
To replace thermocouple, shut gas cock (see owner’s manual); remove burner assembly; disconnect thermocouple from bracket; and attach new thermocouple. Test for leaks: apply soapy water to joints and open gas cock; bubbles indicate a leak. If OK, light pilot.
=== !!! SAFETY !!! ===
Before repairing a gas or electric water heater, shut off its gas line or electric circuit; then drain the tank. Never attempt to replace a gas control valve or pipes that bring gas to it. Never replace a pressure relief valve. Call a plumber to service or replace these critical safety items.
Poisonous carbon monoxide can leak from a faulty draft hood. With the burner on, hold your hand near the hood. Exhaust should rush into the hood; if it spills out, turn off the heater and have the vents inspected.
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Troubleshooting: Gas water heaters
SYMPTOM: |
POSSIBLE CAUSE: |
SOLUTION: |
No hot water Pilot light wont stay lit Not enough hot water Water too hot Heater leaks Heater noisy Hot water dirty |
Pilot light out Blockage in pilot orifice Loose thermocouple connection(s) Faulty thermocouple Burner shut down Temperature control set too low Burner flame orange, not blue Temperature control set too high Faulty thermostat Blocked flue Pressure relief valve venting water Tank rusted Sediment in tank causes rumbling Faulty burner whistles or pops Sediment in tank |
Relight pilot, following instructions on unit Clean pilot orifice. Tighten thermocouple connections Replace thermocouple. If pilot is lit, press reset button. Check control; reset if necessary. Adjust air shutters, or have serviced. Check control; reset if necessary. Have serviced. Check draft hood (see For your safety), or have serviced. Operate lever; if leak persists and temperature is OK, have valve replaced. Have heater replaced. Drain and flush tank (see text above); then refill. Adjust air shutters, or have burner ports serviced. Drain and flush tank (see text above); then refill.
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[Degree of difficulty: Simple --Average ---Complex]
Electric water heater
Components of Electric water heater:
- Cold water in
- Pressure relief valve
- Upper heating element
- Dip tube
- Lower heating element
- Hot water out
Note: Details of repair and disassembly may vary, depending en model, If year heater differs markedly from this one, consult the service manual or a plumbing contractor.
Troubleshooting: Electric water heaters
SYMPTOM: |
POSSIBLE CAUSE: |
SOLUTION: |
No hot water Not enough hot water Water too hot Heater leaks Heater noisy Hot water dirty
|
High-temperature cutoff tripped Faulty thermostat Faulty heating element(s) Thermostat set too low Faulty thermostat Faulty lower heating element(s) Thermostat set too high Faulty thermostat Faulty high-temperature cutoff Grounded heating element(s) Pressure relief valve venting water Tank rusted Heating element gasket leaking Sediment in tank Heating elements scale-encrusted Sediment in tank |
Push reset button on high-temperature cutoff. Test both thermostats; replace faulty thermostat. Test; replace if faulty. Adjust settings and reset. Test both thermostats; replace faulty thermostat. Test; replace if faulty. Adjust settings and reset. Test both thermostats; replace faulty thermostat. Replace it if overheating occurs Test and replace Operate lever; if leak persists, have plumber check pressure relief valve. Have water heater replaced. Tighten mounting bolts. If leak persists, replace gasket. Shut off power; drain and flush tank until water runs clear, then refill. Replace elements. Drain tank ; flush until water runs clear, then refill. |
[Degree of difficulty: Simple --- Average --- Complex ---Volt-ohm meter required]
Servicing a high-temperature cutoff:
1. To test high-temperature cutoff, first shut off power. Remove top panel cover and push aside insulation. Disconnect leads from heating element terminals. With VOM on RX1, probe terminals on left of reset button, then on right. Look for zero reading each time. If readings are high, replace cutoff unit.
2. To replace cutoff (and thermostat), label and disconnect all wires. Pull unit from bracket. (On some models, cutoff and thermostat can be replaced separately by removing copper bus and gently prying lock tab on other side.) Fit new unit into place and reconnect wires. Press reset button; then restore power.
Servicing the thermostats:
1. To test lower thermostat, shut off power; then let water in the tank cool. Disconnect leads from heating element terminals, and use screwdriver to turn temperature control dial to highest setting. Set VOM on RX1; then probe terminals 1 and 2. Look for zero ohms reading; if higher, replace thermostat (Step 2, left).
2. To test upper thermostat, disconnect leads, turn dial to the highest setting, and probe terminals 1 and 2 as described above; look for zero ohms reading. With VOM still on RX1, probe terminals 1 and 4. Meter should read infinity. If reading is lower, replace thermostat (Step 2).
Tasting and replacing a heating element:
1. Shut off power. Disconnect element leads. Set VOM on RX1 and probe both element terminals. If VOM reads infinity, replace element; any other reading means element is OK. To test for ground, set VOM on RX1000; probe one element screw and mounting bracket. Element is safe if reading is infinity.
2. To replace heating L element, drain tank. Take out mounting bolts to remove heating element (or unscrew a threaded element). Clean any corrosion; then install new gasket and element. Refill tank. Check for leaks at gasket; tighten if necessary. Press reset button.
