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Troubleshooting Water Heaters


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Residential Electric Troubleshooting Table
Nature of Trouble: Possible Cause: What/How to Service:
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
  1. Shorted or loose wiring
  2. 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 Troubleshooting Table
Nature of Trouble: Possible Cause: What/How to Service:
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.)

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Frequently Asked Questions

Q. "I see that you sell tankless instantaneous gas and electric water heaters. I even found that you sell large commercial as well as small and undercounter water heaters but I do not see any regular residential water heaters. Have I missed them or don't you sell them?"
A.We do not sell "standard" water heaters because they are a product that is sold at home centers (many are priced near cost). When you add shipping costs (they are heavy and bulky), it simply doesn't make it feasible/practical/economical to sell them on the Internet. We are good at what we do, and we wish to be very competitively priced. With regular "standard" residential water heaters it simply isn't practical from our viewpoint.

Q. "What does 'Grounded Element' mean?"
A.A broken element that is possibly touching the inside of the tank completing the electrical circuit.



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