Upper thermostat question

[chrisj1123]

So I am having a problem with having enough hot water from my water heater. We can only take about 3- 15mins showers before we are out of hot water. This didn't use to be the case. I have tested both elements and both test good. I have tried to test both the upper thermostat and lower but I have a question on the upper.I attached a picture of the upper thermostat for reference. I turned off the power, turned the thermostat to the hottest setting and checked for continuity between L1(top left) and T2 (bottom left) and it checked good. I also checked between L1 and T4(bottom right) to see if power was going to the bottom element. At this point I thought it was not supposed to because of the top element being on but I had continuity there as well. So then I switched the thermostat to the lowest setting and checked again and I had continuity on both the upper and lower again.

My question is..... Is this correct or do I have a bad upper thermostat

 

[johnjh2o]

If the tank is making some hot water but not enough the lower element is the one that needs replacing.

 

[chrisj1123]

The lower element is testing good. Should I still replace it? How can I test the bottom thermostat?

 

[johnjh2o]

When the upper thermostat is satisfied the power then feeds the lower thermostat at that point if you have 220 volts at the lower element the thermostat is OK.

 

[chrisj1123]

Right I understand that. And that is where my question comes into play. I get continuity on both the upper element lead and lower element lead from the upper thermostat at the same time. So it is like the upper thermostat is sending power to both the upper and lower when its only supposed to be sending power to one or the other.

Maybe Im missing something but it seems to me like the upper thermostat is not working properly to me

 

[johnjh2o]

It is but only 110 volt. 220 is needed to operate the elements.

 

[chrisj1123]

Just did some more checking and it looks like I have 240 going through both elements. I can turn the bottom thermostat down and get it to show 0 going through the element. The top thermostat im still not sure Im checking everything properly but I can get 240 going through the element but it seems like I cannot get it to turn off at all but maybe that's the way its supposed to be. Im at a loss it looks as if everything is working properly but the water doesn't seem to last as long as it use to.

 

[Matt30]

What are your ohms readings on the elements?

 

[chrisj1123]

I dont have an actual ohms meter just a Fluke meter with continuity setting

 

[Matt30]

If the thermostat is sending power to the bottom element, I'd say it's working fine. Without knowing the resistance I would have to guess a bad bottom element

 

[johnjh2o]

If the thermostat is sending power to the bottom element, I'd say it's working fine. Without knowing the resistance I would have to guess a bad bottom element

That is the direction I have been trying to point him in.

 

[Matt30]

Strength in numbers!

Electrical questions can be tricky to diagnose, since we aren't doing an on site diagnosis but just going by what you tell us you have done.

 

[Matt30]

I have been fooled by my multi-meter a few times over the years when dealing with elements.

Earlier this year we had a customer with a similar situation, but water was barely hot. Everything checked out fine on my meter and elements were reading fine. I chalked it up to a bad thermostat. Next morning, still no hot water. So I went back and pulled both elements, and the top element had almost looked like a deep fried fish. There was just something from the water baked into it. So it was working, but whatever it was wasn't allowing it to heat. I cleaned it up, put it back in and there was hot water in an hour.

Moral of the story....sometimes a visual inspection is better

 

[chrisj1123]

Thanks for all the help. I have had bad elements before in my other houses and have been able to diagnose them pretty easy. This one seems like everything I check is checking good.
As far as the top thermostat sending power to the bottom I know what it is suppose to do but like I have been trying to explain it seems like it is sending power to both elements at the same time. If I check the power with it on the hot or cold setting I have power going to both elements (243 volts) at the same time. That is what was confusing me and making me think the top thermostat was bad.
Im just gonna replace both elements tomorrow and see what happens because now my wife is saying there is no hot water after 3 hrs since the last shower. So I have to do something.

 

[Mr_David]

I had to pick through what you were describing.
I have never diagnosed an electric WH by checking continuity on thermostat so I was a little confused.
I do check for continuity on the elements
1st but you have to disconnect them.
Check the terminals through the element 1st ( with wires disconnected from element ).
NO continuity=element no good
continuity = maybe okay
Then from each element terminal to the tank.
If you get a reading to the tank the element is burned out.

QUOTED:
"turned the thermostat to the hottest setting and checked for continuity between L1(top left) and T2 (bottom left) and it checked good. I also checked between L1 and T4(bottom right) to see if power was going to the bottom element. At this point I thought it was not supposed to because of the top element being on but I had continuity there as well. So then I switched the thermostat to the lowest setting and checked again and I had continuity on both the upper and lower again.

The reason is the blue wire from Upper Element and red one from the Lower Element are on a common terminal. If the lower thermostat is calling for heat then the circuit is closed through the lower element and you will have continuity between L1 <> T2 and also L1 <> T4
When you have the power on you will only have power to either T2 or T4

If you have continuity between T2 <> T4 then lower stat is closed( calling for heat)


here is where you skipped the important part. Voltage will only be hot to the lower stat when the upper element switches from T2 > T4

You have to check for voltage through the stats NOT Continuity.

check the voltage to ground ( tank ) with power on.
THE best way to test element is with an AMP meter.

Take watts rated on the element and divide by the voltage should give you the expected amperage. about 18 amps

Hope that helps.