Electric Hot Water Heater Thermostat Operation

[Pete in Post Falls]

Good Day,

First time in the forum! A newbie!

A question about the operation of a dual element thermostat.

Background: Users complain of running out of hot water.

Symptoms:

Continuity through both elements. 300 volt meggar shows infinite to tank. Voltage checks show 220 to upper element, no voltage to lower thermostat (?). I thought Thermostat bad on one side and replaced it. NO CHANGE in symptons.

I did miswire the new thermostat the first time (no smoke/no arcs).

Did I get a bad replacement thermostat? Smoked the first one?
Something else?

Pete in Post Falls

[Wgoodrich]

Easiest and most reliable test in testing a heating element on a water heater is to remove one wire from that bottom heat element [most likely the bad part] Then take a normal voltage meter and test from the one empty screw of the heating element to the metal tank. If you get no voltage then potential is equal with element and tank showing an element has broken open.

I suspect you will find a bad bottom heating element.

Let us know what you find.

Wg

[Anonymous]

I received the following from State Inc, the manufacturer of the replacement upper Thermostat:

Quote

Subj: RE: Upper Thermostat - 9001954
Date: 2/24/2003 7:37:06 AM Eastern Standard Time
From: "Stateind, Help" <help1@hotwater.com>
To: <PPryor3483@aol.com>
Sent from the Internet (Details)






Thank you for contacting State Industries and thank you for using our product. After reviewing the information you have requested, residential heaters only allow one element at a time to operate.
State Technical Information Center
Ashland City, TN

End quotation.

I guess from that only one element is all that's turned on at a time.

I'm writing back to ask when should each be turned on.

Pete in Post Falls

[Anonymous]

The last word is:


Subj: RE: Upper Thermostat - 9001954
Date: 2/24/2003 3:48:13 PM Eastern Standard Time
From: "Stateind, Help" <help1@hotwater.com>
To: <PPryor3483@aol.com>
Sent from the Internet (Details)




on a cold tank the top comes on first and once it is satisfied then the lower element is activated and the top stops heating


Pete in Post Falls

[Wgoodrich]

Most water heaters have two 4500 watt heaters. The bottom element of a residential water heater does most the work. It is true both heating elements never heat at the same time on a residential water heater.

Inside your water heater you will find your cold fill tube entering into the tank at the bottom of the tank. When the water heater is cycling at normal temperatures without hot water being used the top element will cycle on and off.

When you use a lot of hot water then cold water enters the bottom of the heater and the bottom element does the major part of bringing the heat back to normal storage temperature. At the time the bottom element is heating the top will be shut off. At the time the top is heating the bottom is shut off.

The purpose of this is that heat rises. You don't want a blast of real cold water sucked into the pipes going to the shower nor do you want a blast of hot water to come through the pipes to the shower. This would be a hazard to safety.

The intack cold water line causes the cold water to mix with hot water maintaining a reasonable outgoing hot water temperature while the bottom element reheats the water to normal hot water levels.

Then back to the top element that maintains the heat at rest times.

I suggest you take one wire off the bottom heat element. Then take a voltage reading to confirm that you read 120 volt to the metal water heater tank. This will tell you the heating element is good.

If you find 0 volts between that empter element screw and the metal tank then you have a bad bottom heat element.

To replace that element you can shut off your incoming cold water to the water heater. Turn off power to your heater. Then turn on a hot water faucet and let run untill it quites running then immediately shut off that faucet.

Then with all valves closed open your cover on the bottom water heater element. Look to see the mounting of that element. Look on the face or side of the face of that element and it will tell you the wattage rating of that element. Go to the hardware store and buy a new replacement water heater element that matches the mounting and the wattage rating of your existing element.

Some elements screw into the tank some elements use for screws and a bracket.

Set you new element on the floor by the water heater. Then take serveral bath towels and pack then below that element around the face of the water heater to catch any water.

Keep in mind you have a vacuum inside the water heater tank. If you remove the old element and pull it out of the tank then grab the new element and slide it in quickly and push it to the tank so the seal will seal you should only get a couple of GLUBS of water out of that tank due to the vacuum in that tank with all valves closed. No air can come into the tank so little water can come out of that tank in the exchange.

Warning is that I suspect your heater to have a build up of lime in the bottom of the tank that caused your element to over heat and burn out due to being covered in lime. I also suspect that when you try to get that element out the element will have over heated and warped to where you will have to force the element by bending back and forth while pulling it out of the hole. You can still do this just be prepared.

If you find full of lime then you can go ahead and install the new heating element to buy you some time. When you can you need to remove the pipes and use a two wheeler and take the water heater outside then remove the heating element again while outisde using a bent coat hanger to keep the lime stirred up while letting the water drain out. This will flush out most the lime as the water heater drains. Once the water heater is drained take a flash light and look inside to see how much lime is left. Scoop out the lime and you have an old water heater refurbished like new again to reinstall.

Hope this helps

Wg