Thread: Is there anything wrong with my A.O. Smith heater?

I just called A.O. Smith customer service. I didn't call them before because a local shop told me that they don't take calls directly from residential customers, that you have to be a retailer. He was wrong. Anyway, the lady at Smith's customer service was very helpful. She didn't know why the elements would have two different part numbers. She repeated what the guy at Lowes said, that I can use the same part number in both the top and bottom as long as the wattage is that same (and what's recommended). I guess I'll find out tomorrow.

Originally Posted by Retired USAF

I just called A.O. Smith customer service. I didn't call them before because a local shop told me that they don't take calls directly from residential customers, that you have to be a retailer. He was wrong. Anyway, the lady at Smith's customer service was very helpful. She didn't know why the elements would have two different part numbers. She repeated what the guy at Lowes said, that I can use the same part number in both the top and bottom as long as the wattage is that same (and what's recommended). I guess I'll find out tomorrow.

Hey just because I'm Army, I just posted that in the above response.

I took your post above a different way. Now I see what you mean with it.

Ok, I shut the power off, drained the tank, changed elements, turned water back on & filled tank, bled the pipe to get the air out, & turned the electric back on. I now get a reading off of the top element but don't get one from the bottom element.

Does the top and bottom fire differently, or should there be a constant reading from both of them?

Also, of the two wires that connect to the element, it doesn't matter which one goes where, right?

On a side note, the top element that was in it was shorter than the bottom one. It was only 11 1/2 inches long. The inside lining of the tank still looked great, but the anode rod looks like something out of science fiction movie.

Just went out and checked again with the multimeter. This time, I get no reading off of the top element but get 240V from the thermostat. However, I now do get the 240V reading from the bottom element but no reading from that thermostat. It seems as though they're both working though because I have wicked hot water now. I turned both thermostats down now because of how hot it is. These electrical readings are really throwing me for a loop because I don't know how this stuff is supposed to work.

Troubleshooting Walk-Through

We get so many questions about electric water heaters, and find ourselves answering similar questions so often that we decided it would be good to have a little troubleshooting guide just for them. However, take a quick look at the other questions below that don't deal specifically with "no hot water" problems. Do be aware that electricity is dangerous and that you can kill yourself pretty easily if you don't know what you're doing. Lots of folks come to The Tank because they don't want to hire an electrician or plumber to fix a problem, but saving money is meaningless if you lose your life in the process. The usual complaint is, suddenly there is no hot water. That usually means the high limit has tripped. The first thing to do always, is to turn off the power, remove the cover from the upper element port, take out the insulation, remove the cover to the element assembly, if needed, and press the red reset button, circled at right, since its red doesn't show up too well here. If you don't hear the button click or don't have power after pressing it, then the high limit is bad. If this is so, use your nose. Can you smell anything burned? Are there scorch marks or signs of water? If so, that's what caused the problem. Also, if the high limit didn't click when you pressed it, the limit might be working OK and not be the problem. A volt-ohm meter can tell.

If it's wet inside the compartment, it may be a sign the water heater is on its last legs. Water can also cause the spring clip that holds the thermostat against the tank to rust. If the clip is damaged, the thermostat won't read properly and may cause the high limit to trip. Also, every time you inspect an element port, put everything back the way you found it. There is a reason for the cover and insulation. Often when a high limit trips, it's a symptom of another problem. We're going to take you on a tour as you follow the electricity down from the breaker box, eliminating suspects as we go. Remember, any time you open element ports, you should turn off the power. You'll need a multimeter for this. Since we're fond of analog meters, we'll be using the terms associated with their use. If you are unfamiliar with multimeters and 240 volts, DON'T ATTEMPT THIS. HIRE A PLUMBER OR ELECTRICIAN.

First check the power at the circuit breaker to make sure the breaker isn't bad. Also make sure there are two 30-amp breakers running at 230 volts. If something less than that is being used, that right there is a problem. Then open the upper element port and check the screws above the high limit, then under the high limit. If there is power at the circuit breaker, but not at the high limit, check power at the junction box on top of the heater Next place to check is at the screw terminals on the upper element (see picture, yellow circle) after making sure the upper thermostat is turned up high. If you check, you should have about 240 volts at the terminals on the upper element. If not, then either the thermostat is bad or you need a wiring diagram to ensure that all the wires go the right place. If you have power to the upper element, but the element isn't heating, check it with an ohm meter. Turn power to the heater off, and use the meter to double-check that it's really off, then undo one wire from the element and bend it out of the way. Set your meter in the ohms times one or two scale. Test between the two screws on the element. If the needle moves most of the way over, it's good. Then you switch to ohms times 1,000 scale and put the lead on one screw of the element and one on the flange of the element to ground to test for leaks to ground. Check first one screw, then the other. If you get any reading at all, there is a leak to ground and the element needs to be replaced. At this point, you know you have power to the upper element and whether the element is good or bad. If it's good, you're getting a half tank of hot water. If there is insufficient hot water, then the next thing to do is check the lower element. Check in the same way as the upper element for 240. It's normal to have 120 at an element when it's off. If the thermostat is working correctly, you should find about 240 at the lower element between the two terminals. Again check for leaks to ground. If you don't have power to the lower element, check at the lower thermostat or follow the wires down to the lower element, one directly one to the thermostat. If you check between those two wires, you should have 240 volts assuming the bottom of the tank is cold. If not, then the upper thermostat is not switching correctly and needs to be replaced. If you find you don't have 240 from the other side of the thermostat and the wire on the element, then the lower thermostat is bad and not switching. If you find you have 240 at element screws but it's not heating, then the element must be bad, but you should already have tested for that.

That was all kinda Greek to me. If something is wrong or isn't wrong, shouldn't you get the same readings all the time instead of them switching back and forth? I know I'm asking a lot of questions, but I'm trying to help myself understand this.

Check the lower element.


Check in the same way as the upper element for 240. It's normal to have 120 at an element when it's off. If the thermostat is working correctly, you should find about 240 at the lower element between the two terminals. Again check for leaks to ground. If you don't have power to the lower element, check at the lower thermostat or follow the wires down to the lower element, one directly one to the thermostat.

If you check between those two wires, you should have 240 volts assuming the bottom of the tank is cold. If not, then the upper thermostat is not switching correctly and needs to be replaced. If you find you don't have 240 from the other side of the thermostat and the wire on the element, then the lower thermostat is bad and not switching. If you find you have 240 at element screws but it's not heating, then the element must be bad, but you should already have tested for that.

In spite if getting different readings every time I check it, I have plenty of hot water now. The more I try to understand it, the more confused I make myself, so at this point I'll just keep an eye on it. If the house hasn't burned down by next week, I'll claim victory. Thanks for all the input!