Troubleshooting Tips - Water Heaters

Before you call for service …

There are many minor problems that you can easily fix yourself. If your water heater isn't working properly, look for the problem you're experiencing on this chart and see if it's a do-it-yourself job.

Residential Electric Water Heater
Problem Possible Causes What to Do
No Hot Water

Manual switch turned off

Turn to ON

Blown fuse at breaker

Replace or reset

High limit switch tripped

Manually reset ECO button

Upper thermostat defective

Check and replace

Upper element defective

Check and replace

Grounded thermostat

Check and replace

Thermostat out of calibration

Check, tighten and replace

Improper wiring - Shorted or loose wiring  Undersized service wire

Check and replace

Not Enough Hot Water

Thermostat set too low

Increase thermostat setting not to exceed 120 degrees

Defective lower element

Check and replace

Defective lower thermostat or miswired thermostat

Check and replace

Improper wiring

Rewire per wiring diagram

Loose wiring

Check and tighten

Improper heating elements

Check wattage and replace

Scale formation on heating element

Check elements; clean or replace

Thermostat not flush with tank

Position thermostat so back touches the tank

Poor grounding of tank

Check grounding and tighten

Heater is undersized

Resize residence and compare

Damaged dip tube

Check and replace

Water Too Hot

Thermostat setting too high

Lower thermostat setting
  Thermostat out of calibration Check and replace
  Thermostat not flush with tank Position thermostat so back
touches the tank
  Grounded element Check and replace

Slow hot Water

Heating elements too small

Check wattage and replace

Lower thermostat is defective

Check lower thermostat and replace

Noisy heating element

Scale build-up on elements

Remove, clean or replace

High watt density elements in the heater

Install low watt density elements

Excessive relief valve operation

Excessive water pressure

Install proper pressure reducing valve on cold side Check for open or closed system. Replace T&P valve and install thermal expansion tank.

Excessive temperature

Check thermostat; lower setting or replace; check for grounded element.

Rusty or black water

Scale formation on elements

Clean or replace elements

Anode rod dissolved

Check anode rod and replace

Excessive sediment build-up

Try to drain tank; replace tank if sediment build up is excessive

Water heater is leaking

Cold in or hot out joints

Check joint and repair

T&P valve

Check valve and replace Caution: Do not confuse normal T&P operation as a leaking tank. If the puddle dries up, then look for a T&P problem.

Heating elements, anode rod and gaskets

Check, tighten and replace

Inner tank has a pin hole

Replace water heater When diagnosing a leaker – you will notice a puddle of water on the floor, next to the heater, that will not go away.

Smelly water (rotten egg odor)

Bacteria formation inside water tank

Clean tank using chlorine bleach Replace anode rod if deteriorated Add automatic chlorine feeder to cold water inlet side of tank

Milky water

Aerated water

Allow a glass of hot water to set for a few minutes. If the water turns clear, the condition is a natural occurrence

Residential Gas Water Heater
Problem Possible Causes What to Do

No Hot Water

Gas supply turned off

Turn on gas supply

Pilot not lit

See Unable to light pilot and Pilot does not stay lit

Not Enough Hot Water

Thermostat set too low

Adjust thermostat

Burner orifice is clogged

Inspect and clean

Low gas pressure

Check gas supply pressure and manifold pressure

Venting downdraft (or other improper draft)

Check for proper up draft venting. Check for other drafts that could blow out the pilot light.

Clogged flue

Inspect and clean flue way

Defective thermostat

Replace gas control valve

Defective dip tube

Check and replace dip tube

Heater is undersized

Adjust Peak Hour Demand

Unable to light pilot

Gas supply turned off

Turn on gas supply

Gas cock knob dial not positioned correctly

Check lighting instructions. Set control knob

Defective thermocouple

Check and replace thermocouple

Defective safety magnet assembly

Check and replace gas valve

Pilot burner orifice clogged

Clean or replace

Pilot tube pinched or clogged

Clean, repair or replace

Poor thermocouple connection

Check and tighten

Air in gas line

Purge air from gas line

Thermostat’s single use ECO is tripped

Check ECO and replace gas valve

Gas valve defective

Check gas valve

Pilot does not stay lit

Poor thermocouple connection

Tighten connection at gas valve

Thermocouple defective

Check thermocouple and replace

Thermocouple not in pilot flame

Move tip of thermocouple so it is immersed in pilot flame

Defective safety magnet assembly

Check magnet and replace gas valve

Venting downdraft (or other improper draft)

Check for proper up draft venting. Check for other drafts that could blow out the pilot light

Clogged flue

Inspect and clean flue way

Pilot partially clogged

Inspect and clean supply tube and pilot burner

Improper gas pressure

Check and adjust supply side

Main burner will not stay lit

Low gas pressure

Check gas supply pressure

Main burner orifice clogged

Clean or replace

Main burner supply tube clogged or pinched

Clean, repair or replace

Defective magnet assembly

Check and replace gas control valve

Defective thermocouple

Check and replace

Poor thermocouple connection

Inspect and tighten

Defective main valve

Replace gas control valve

Improper venting

Check venting for proper sizing and down drafts

Scale on burner and pilot assemblies

Condensation

Excessive condensation caused by undersized heater, poor venting or continued use

Contaminated atmosphere

Check for contaminant causing chemicals near the heater

Sooting

Combustion air inlets or flueway is restricted

Remove obstruction or debris from heater or flueway

Not enough combustion or ventilation air supplied to room

Improve combustion air or ventilation air supply

Improper gas pressure

Check and adjust

Burner orifice dirty

Inspect and clean

Yellow flame

Scale on top of burner

Shut off heater; allow to cool; clean burner plate

Burner orifice dirty

Inspect and clean

Flue way clogged

Inspect and clean

Improper gas pressure

Check and adjust

Burner flame noisy (whistling)

Improper gas pressure

Check and adjust

Burner orifice dirty

Inspect and clean

Burner flame floats

Improper gas pressure

Check and adjust

Wrong orifice

Install correct orifice

Clogged flue

Inspect and clean flue way

Burner flame too high

Improper gas pressure

Check and adjust

Wrong orifice

Install correct orifice

Water too hot (follow by pilot outage)

Thermostat setting too high

Adjust thermostat to lower setting

Thermostat out of calibration

Check and replace thermostat

Slow hot water recovery

Burner orifice clogged

Check and clean

Excessive drafts

Locate and eliminate drafts

Clogged flue

Clean flue chamber

Improper gas pressure

Check and adjust

Noisy water heater (rumbling and sizzling)

Scale or sediment build up in bottom of tank

Clean tank

Baffles loose

Reset and tighten

Condensation on main burner

Inspect for condensation (normal) and tank leaks

Excessive relief valve operation

Excessive water pressure

Install proper pressure reducing valve on cold side Check for open or closed system. Install expansion tank.

Excessive temperature

Check thermostat; lower setting or replace

Rusty or black water

Anode rod dissolved

Check anode rod and replace

Excessive sediment build-up

Drain tank; replace tank if sediment build up is excessive

Water heater is leaking (Gas water heaters produce condensation that may drip on the floor. Condensation will produce only a few drips or small puddles that evaporate.)

Cold in or hot out joints

Check joint and repair

T&P valve

Check valve and replace Caution: Do not confuse normal T&P operation as a leaking tank. If the puddle dries up, then look for a T&P problem.

Immersion thermostat or anode rod is loose

Check, tighten and replace

Inner tank has a pin hole

Replace water heater (When diagnosing a leaker – you will notice a puddle of water on the floor, next to the heater, that will not go away