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Lower heating element not working. 

If the lower heating element (or, more 

rarely, the lower thermostat) is not 

working, you will have some hot water 

but not as much as before. Because the 

lower element does most of the work, 

the lower element usually wears out 

before the upper element. Replace the 

lower element and/or thermostat if 

necessary (see page 25-27). 

Temperature Too High

If the water temperature is too hot:

•  Install or adjust the Thermostatic 

Mixing Valves (see manufacturer’s 

instructions), or

•  Adjust the thermostat(s) on the water 

heater (see Step 10 in the Installation 

section of this manual). 

A nonfunctioning thermostat or a 

shorted heating element can cause 

extremely hot water. If the Temperature 

and Pressure Relief Valve (T&P Valve) 

releases large amounts of very hot 

water, it is likely due to a shorted 

heating element, or more rarely a 

nonfunctioning thermostat, or the 

thermostat does not fit snuggly against 

the tank.  Very high water temperatures 

can also cause the Energy Cut Off (ECO) 

to trip (see page 22). Turn power off 

until this problem is fixed.

Low Water Pressure

Check both the cold and hot water at a 

sink to determine if the lower pressure 

is only on the hot water side. If both 

hot and cold faucets have low pressure, 

call your local water utility. If the low 

pressure is only on the hot water side, 

the primary causes of this are:

•  Melted heat traps or dip tube. 

Soldering copper pipes while they are 

connected to the water heater can 

melt the heat traps inside the hot and 

cold water connections or the dip tube 

(cold water side). Melted heat traps or 

a melted dip tube can restrict the flow 

of hot water. If that’s the case, replace 

the heat traps or dip tube. 

•  Partially closed supply valve. Open 

the water heater’s supply valve fully.

Drips from T&P Relief 

Valve Discharge Pipe

A small amount of water dripping from 

the Temperature and Pressure (T&P) 

Relief Valve usually means the water 

pressure is too high or you need a 

properly sized and pressurized Thermal 

Expansion Tank. Refer to Step 1 in the 

Installation section of this manual for 

more information. A large amount 

of hot water coming from the T&P 

discharge pipe may be due to the tank 

overheating.

WARNING! Do not cap or plug the 

T&P relief valve or discharge pipe, and 

do not operate the water heater 

without a functioning T&P Relief Valve 

- this could cause an explosion.

Water pressure too high. 

High water 

pressure can cause the T&P Relief Valve 

to drip. Install a Pressure Reducing 

Valve (PRV) on the main cold water 

supply line. Adjust the PRV to between 

50-60 psi (345-414 kPa).

Thermal Expansion Tank.

 Install a 

Thermal Expansion Tank. If a Thermal 

Expansion Tank is already installed and 

the T&P Relief Valve discharge pipe 

drips, the Thermal Expansion Tank may 

be pressurized to the wrong pressure or 

the internal bladder may be defective. 

Refer to the instructions that came with 

the Thermal Expansion Tank for more 

information. 

Debris.

 In rare cases, debris can stick 

inside the T&P Relief Valve preventing 

the valve from seating fully. In that case, 

the T&P Relief Valve discharge pipe will 

drip. You may be able to clear debris 

from the T&P Relief Valve by manually 

operating the valve, allowing small 

quantities of water to flush out the 

debris. See the label on the T&P Relief 

Valve for instructions. 

If the water pressure is between 

50-60 psi (345-414 kPa), a Thermal 

Expansion Tank is installed and properly 

pressurized, and the valve has been 

cleared of any debris, and it still drips, 

the valve may be broken—have a 

qualified person replace the T&P relief 

valve.

Water Odor

Harmless bacteria normally present 

in tap water can multiply in water 

heaters and give off a “rotten egg” 

smell. Although eliminating the bacteria 

that causes “smelly water” with a 

Chlorination system is the only sure 

treatment, in some cases, the standard 

anode rod that came with your water 

heater can be replaced with a special 

zinc anode rod which may help reduce 

or eliminate the odor. Contact a 

qualified person.

NOTE:

 To protect the tank, an anode 

rod must be installed in the water 

heater at all times or the warranty is 

void. 

In cases where the “rotten egg” smell 

is pronounced, you can raise the tank 

temperature to 140°F (60°C) in order to 

reduce bacteria growth in the tank.

WARNING! Because higher 

temperatures increase the risk of 

scalding, if you set the thermostat(s) 

higher than 120°F (49°C), Thermostatic 

Mixing Valves are particularly 

important (see page 4).

Commercial Electric Water Heater Use and Care Guide • 23

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Summary of Contents for DEJC-50

Page 1: ...T Read this manual and the labels on the water heater before you install operate or service it If you have difficulty following the directions or aren t sure you can safely and properly do any of this...

Page 2: ...ermostat access Lower Element and Thermostat access T P relief valve Water shut off Electrical junction box Expansion tank Drain pan discharge pipe Drain pan Drain valve T P discharge pipe Cold water...

Page 3: ...ANGER indicates hazardous situation that if not avoided will result in death or serious injury WARNING WARNING indicates a hazardous situation that if not avoided could result in death or serious inju...

Page 4: ...lly mix hot and cold water to limit the temperature at the tap Mixing valves are available from your local plumbing supplier Follow manufacturer s instructions for installation and adjustment of the v...

Page 5: ...s from plumbing or leaks from the water heater itself can damage property and could cause a fire risk If the water heater is subjected to flood conditions or the thermostat s have been submerged in wa...

Page 6: ...1 46 41 36 34 30 29 9 LPH 384 345 256 230 192 173 153 138 128 115 110 5000 5000 GPH 113 101 75 68 56 51 45 41 38 34 32 10 LPH 426 384 284 256 213 192 170 153 142 128 122 5500 5500 GPH 126 113 84 75 63...

Page 7: ...3 Before you start be sure you have and know how to use the following tools and supplies Plumbing tools and supplies appropriate for the type of water pipes in the plumbing system Threaded connectors...

Page 8: ...ALCULATING AMPERAGE OVERCURRENT PROTECTION The dual element heater is factory wired for connection to a three wire three phase delta branch circuit non simultaneous operation In addition a ground cond...

Page 9: ...Commercial Electric Water Heater Use and Care Guide 9 Approvals All models are listed by Underwriters Laboratories Inc Model and Rating DELC 30 40 50 DENC 30 40 DEJC 50 66 GETTING STARTED...

Page 10: ...10 Commercial Electric Water Heater Use and Care Guide Thermostat Wiring Diagram A 8 CIRCUIT FOR DUAL ELEMENT HEATER GETTING STARTED GETTING STARTED...

Page 11: ...ater supply line and adjust the water pressure control to between 50 60 psi 345 414 kPa If the property does not have a Pressure Reducing Valve install a PRV on the main water supply line and set it t...

Page 12: ...d can shut off the water heater s water supply if a leak occurs Figure 6 A suitable drain pan piped to an adequate drain can help protect flooring from leaks and drips Install a suitable drain pan ava...

Page 13: ...spect the drain pan pipes and surrounding area regularly and fix any leaks found Drain pans are available at local plumbing supplier Leaks are frequently in the plumbing system itself and not the wate...

Page 14: ...heater 1 Completely read all instructions before beginning If you are not sure if you can complete the installation seek assistance from any of the following sources Schedule an appointment with a qua...

Page 15: ...stall it to allow complete drainage of both the T P Relief Valve and the discharge pipe The discharge pipe must withstand 250 F 121 C without distortion Use only PEX copper or CPVC pipe Do not use any...

Page 16: ...ed polyethylene PEX Use fittings appropriate for the type of pipe in the plumbing system Do not use iron or PVC pipe they are not suitable for potable water 2 Connect the cold water supply using 3 4 i...

Page 17: ...Expansion Tank Figure 15 A Pressure Reducing Valve is required if the plumbing system s water pressure is above 80 psi 552 kPa Figure 16 The Thermal Expansion Tank should be pressurized with air to ma...

Page 18: ...o access the electrical junction box Figure 18 The water heater s electrical requirements can be determined from the data plate 5 Install wiring in an approved conduit if required by local codes Use a...

Page 19: ...h from electrical shock Check wires with a circuit tester to make sure power is off Open the electrical junction box and remove the lower thermostat access panel Do not remove the plastic personnel pr...

Page 20: ...temperature setting when you return CAUTION Hydrogen gas builds up in a hot water system when it is not used for a long period two weeks or more Hydrogen gas is extremely flammable If the hot water s...

Page 21: ...uit tester Turn the power off and close the electrical junction box If the water heater is not getting power contact a qualified person to have the wiring or circuit breakers checked 2 Check the upper...

Page 22: ...nections or melted dip tube usually found soon after new installation Plumbing leak Bad lower heating element or lower thermostat Low supply voltage Thermostatic Mixing Valves If the hot water is simp...

Page 23: ...be due to the tank overheating WARNING Do not cap or plug the T P relief valve or discharge pipe and do not operate the water heater without a functioning T P Relief Valve this could cause an explosi...

Page 24: ...cool Figure 25 Water Faucet WARNING Be sure the water runs cool before draining the tank to reduce the risk of scalding 3 Connect a garden hose to the drain valve and place the other end of the hose...

Page 25: ...or thermostat yourself have this work done by a qualified person To replace the heating element you ll need the following tools and supplies Figure 28 Non Contact Circuit Tester Always turn power OFF...

Page 26: ...remove the element Inspect the gasket for damage If the gasket is damaged replace the gasket and re install the element 12 Once the element is successfully installed and there are no leaks replace the...

Page 27: ...f Valve yellow label attached to T P Relief Valve Minerals in the water can form deposits that cause the valve to stick or create blocked passages making the T P Relief Valve inoperative Follow these...

Page 28: ...odel and serial number 2 Item number and part description Key No Part Description 1A ANODE ALUMINUM 1B ANODE MAGNESIUM SMR P72 AND S19 2 T P RELIEF VALVE 3 ELEMENT GASKET 4 ELEMENT 5 UPPER THERMOSTAT...

Page 29: ...expired portion of the warranty WHAT S NOT COVERED Problems caused by improper gas supply line sizing gas type venting connections combustion air voltage wiring or fusing Failure to follow applicable...

Page 30: ...30 Commercial Electric Water Heater Use and Care Guide NOTES NOTES...

Page 31: ...Commercial Electric Water Heater Use and Care Guide 31 NOTES NOTES...

Page 32: ...Copyright 2021 A O Smith All Rights Reserved...

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