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Lower element of electric hot water heater does not come on.

Customer Question
Lower thermostat checks OK....
Lower element of electric hot water heater does not come on. Lower thermostat checks OK. Upper element come on for demand, but connection 4 that feeds lower thermostat tests open. Both thermostats are set at 130F.
Submitted: 8 years ago.Category: HVAC
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Answered in 4 minutes by:
3/16/2009
HVAC Technician: plumber 171, plumbing and heating mec replied 8 years ago
plumber 171
plumber 171, plumbing and heating mec
Category: HVAC
Satisfied Customers: 815
Experience: Master Plumber, Fire Sprinkler, and Jobbing Spec.
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have you checked to see if the element has continuity. from what you are saying the lower stat works fine but it wont heat thats beacuse the element is bad. if your heater is known for high scale it will build up around the element causing it to over heat and burn out shut off the power to the heater and disconect both wiers to the element and test for continuity if no sound the element is bad

 

i recomend if the heater is old 5 years of bettter replace both upper and lower stats as well as the upper and lower elements

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Customer reply replied 8 years ago
I have replaced both upper and lower elements even though both older elements checked OK. New elements checked OK for continuity. Replaced both upper and lower thermostats (Apcon style). All connections check OK except upper thermostat #4, the feed from the upper thermostat to the line side of the lower thermostat. That line is not "hot" and the heating element is not energized. By the way the old upper and lower thermostats showed the same condition, even though the water heater had been performing properly for over one year.
Customer reply replied 8 years ago
Awaiting reply from plumber 171. Answer he provided was what I already knew or had done. Need specific answer for why upper thermostat is not working as expected.
HVAC Technician: plumber 171, plumbing and heating mec replied 8 years ago

it is verry possible the line became broken in the jacket this can happen if it over heats the wire gets brittle and breaks. if the heater is older then 5 years get a new on ( just recomendation ) if not and you have electrical ( sounds like you do ) fish a new wire down to the element but first try to test for continuity from the upper stat wiers to the lower stst wiers first

 

one more thing is there a reset button on your lower stat ( they are usualy on the upper one ) if so see if it triped first

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Customer reply replied 8 years ago
Checked continuity of black wire from connection 4 on upper thermostat to connection 1 of lower thermostat - checks OK. Problem seems to be that connection 4 on upper thermostat is not energized when cold water heat demand occurs. Have rechecked wiring, continuity, and reset button several times. Tried to reverse connection 4 for upper element with lower thermostat connected to connection 3. Lower element was energized, but upper element was open (not energized). Tried to understand how upper thermostat functions internally, could not find any information in that detail. Still believe that upper thermostat connection 4 should be energized when cold water demands heat function. Really hope you can help me understand this problem, I would like to pay you for your usable advice.
HVAC Technician: plumber 171, plumbing and heating mec replied 8 years ago

most electric heaters the top element heats up first then the lower they usualy never heat up at the same time first the top goes on then the botttom goes on afeter it senes temp

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Customer reply replied 8 years ago
Sorry for the delay in response. I just now checked the heater thermostats again. Even though the unit has been on demand for over 3 hours, lower element still is not energized (connection 4 is open) and the outcoming water is barely luke warm (estimate between 80-90F.
HVAC Technician: plumber 171, plumbing and heating mec replied 8 years ago

does the upper stat have a jumper between any of the tyerminals

 

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Customer reply replied 8 years ago
Facing the front of the upper thermostat with the red reset button at the top, there are four connections on the left side and three connections on the right side. The top two connections, right & left, are for the 240 single phase line feed. The middle two left connections have a factory installed shorting bar and no connecting wiring. The bottom left connector has a yellow wire to the upper heating element. The middle connector on the right side has the blue wire to the upper element and the red wire to the lower element. The lower connector (#4) has a black wire going to the line side of the lower thermostat. The load side of the lower thermostat is a black wire completing the circuit to the lower element.
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago
Mark Henley
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3,217
Experience: UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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Hi,

 

What are the stats set at ?

 

Thanks

 

Mark.

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Customer reply replied 8 years ago
Both upper and lower thermostats are set at 130F.
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

Try turning the lower one up all the way to see if we can get it to come on.

 

Thanks

 

Mark

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Customer reply replied 8 years ago
Mark,
I have reset the lower thermostat to 150F. Lower element did not energize, connector 4 lead from upper thermostat remained off. Then reset lower theermostat to 130F and upper thermostat to 150F. Still no response.
Really suspect problem is output at connector 4 of upper thermstat. Don't understand why old and new thermostats exhibit same condition. Again all wiring checks out to circuit diagram.
Customer
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

OK I'm understanding that terminl 4 is the lower right side terminal on the upper stat ?

 

Is that right ?

 

There is a reset on each stat or just the upper ?

 

Thanks

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Customer reply replied 8 years ago
Mark,
Terminal 4 is the lower right side connector on the upper thermostat, it serves as the feed to the line side input to the lower thermostat which has only two connections, no reset button. Only the upper thermostat has a reset button.
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

OK then heres what is happening, just had to make sure you had the typical setup.

 

, the red reset button should kill both circuits and both legs of power.So if one element works they both will.

 

The jumper bar jumps power from the limit switch to the upper thermostat. then if the sensed water is cool the upper thermostat will energize the upper element and hold the lower one off until the thermostat opens ( temp rises on upper element ) .

 

When it opens it sends power down to the lower thermostat and if the lower is calling it will energize the lower element. On a cold tank of water you won't get both elements. How long did you leave it sit after changing the elements ?

 

Thanks

 

Mark.

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HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

I know it sounds back wards of how you would think it would work but thats how it works but both elements don't work at the same time on your heater. If you turn the upper one down as low as it will go and the lower one up as far as it will go and let it brew for a little while you'll see the lower stat energize when the upper satisfies.

 

What was your initial problem ?

 

Thanks

 

Mark.

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HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

 

I found a diagram of it. It shoud graphichelp explain what I'm trying to say.

 

 

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HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi,

 

Here's where I'm going with this, there is a chance that the elements and the thermostats were not the problem to begin with. Your initial conditions sound like it was the dip tube in the tank , it sounds like it broke off sending all the new cold water to the top of the tank instead of the bottom. Therefore , when you would run water the hot water would seem to run out real fast because the cold water was barely being heated before it short circuited to the leaving pipe. All the while you probably had hot water at the bottom of the tank. Even now you will probably still have the same problem until you replace the dip tube.

 

Thanks

 

Mark.

Mark Henley
Mark Henley, Journeyman Technician
Category: HVAC
Satisfied Customers: 3,217
Experience: UA Journeyman Pipefitter , HVAC, Refrigeration, DDC controls. 26 years.Commercial & residential
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Mark Henley and 87 other HVAC Specialists are ready to help you
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Customer reply replied 8 years ago
Mark,
I have been working on this problem since 8:00 AM (EST). I had to step away from the computer for a while, then found 4 responses from you. The arguments about thermostatically sequencing the elements makes sense. The wiring diagram was helpful for understanding upper thermostat function and for that I will accept the answer, even though it doesn't fully solve the problem. The broken dip tube seems a logical issue, and makes sense. I will need to empty the tank tomorrow and pull the cold water pipe/dip tube (if I can) to see if your latest rational is right.Customer
Customer reply replied 8 years ago
I seem to have lost plumber 171 halfway through this exchange. Mark's replies really helped me to understand the nuances of the problem, especially the possibility of the broken dip tube which I will pursue tomorrow. If this information resolves the problem I will report back to your site. Thanks;

Van
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

HiCustomer/p>

 

There was some trouble in getting back to you.

 

The diagram is typical of a two element single phase residential water heater, they don't operate in unison or simultaneously. Just had to verify that with how many limits you had and where the terminals were. I think you will probably find that your dip tube is broken off tomorrow. If not them its really just a matter of the tank being scaled up. Either way though let us know how it turns out.

 

Thanks

 

Mark.

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Customer reply replied 8 years ago
Mark Henley,
I removed the cold water dip tube and found a small (5/32" diameter) hole about 4" from the inside top. The hole was so perfectly round and free of burrs or tears that I am not certain that it wasn't provided at manufacture. I also found the bottom 8" of the tank filled with lime. The lime had congealed into large lumps which proved difficult to remove. Considering the age and condition of the tank, frequent outages requiring replair, and this sort of indeterminate problem, I decided to replace the entire water heater. Did so and now we have hot water. Thanks for your advice. I believe I have found now an exellent source for home maintainence advice.

Van
HVAC Technician: Mark Henley, Journeyman Technician replied 8 years ago

Hi Van ,

 

Glad I could help.

 

Thanks

 

Mark.

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Mark Henley
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