Hot water tank.....question

casserv · May 18, 2011

I think the lower thermostat is showing is age if you replace it it will take care of it.

Kays Supply · May 18, 2011

You don't want it to ground. It is 220V. You want both lines to have 110 when the thermo is on. You will get 110 from either wire to ground. If it goes bad in just the wrong spot, it will short to ground and heat half power all the time. It is rare but I have seen it happen.

General Lee · May 18, 2011

gunnyad said:
both old elements should read exactly the same ohms,you can have a open element and get a reading throught the water ,but it will more than likely be a higher ohm value than the good one.
i like to use a clamp over wire amprobe ,you have to make sure that voltage is at the element to amp it. this takes a little know how ,to get voltage to switch to the bottom .
as someone else said, bottom element can be laying in dirt.
I was young and with dad then and could not beleive a 3/4 bucket of dirt in there.
did many tanks in my younger days. dad had a plumbing shop.

If I remember correctly my digital meter gave me a reading of 12.5 ohms on both elements at their terminals with one wire removed from a terminal. When I checked a terminal with one probe and a probe to a ground (tank itself) my Meter read "OL" which means "infinity" I think. I did get a reading of 46.5 ohms on the top element when I first tested it. I'm not sure if my connection was right and after testing it several other times I couldn't get that high reading again.

I did get two T-stats, one top with a high limit switch and a regular 2 wire T-stat at the bottom.

General Lee · May 18, 2011

Kays Supply said:
You don't want it to ground. It is 220V. You want both lines to have 110 when the thermo is on. You will get 110 from either wire to ground. If it goes bad in just the wrong spot, it will short to ground and heat half power all the time. It is rare but I have seen it happen.

I do need to check the voltage at all points, but honestly I hate messing with electricity, not real comfortable with it. With the power off, I didn't mind checking the ohms.

RaisedonDeere · May 18, 2011

Here's what you can use to troubleshoot a electric hot water heater. I used these websites when I worked on mine not to long ago.. Excellent info...

Hope this helps.. Good luck and be careful.. :thumbsup:

How-to-troubleshoot-electric-problems-with-water-heater

This page explains how a hot water heater works and thermostats in what order..

How to wire water heater thermostat

BubbaJr · May 19, 2011

Something else to check, is to make sure the thermostats are in FIRM contact with the tank. If there is any clearance at all between the surface of the tank and the backside of the thermostat, it will keep that element on longer, since it is not getting a true reading of the tank temperature. It is not uncommon for the bracket that holds the thermostat, to loosen it's grip on the thermostat over time.

Good Luck

General Lee · May 19, 2011

BubbaJr said:
Something else to check, is to make sure the thermostats are in FIRM contact with the tank. If there is any clearance at all between the surface of the tank and the backside of the thermostat, it will keep that element on longer, since it is not getting a true reading of the tank temperature. It is not uncommon for the bracket that holds the thermostat, to loosen it's grip on the thermostat over time.

Good Luck

Yea that is a good tip. When I changed out the T-stats, I made sure I got them as tight against the tank as possible. It was a little tricky, because the electrical wires are so stiff and want to pull the T-stat which ever. So after bending lot the the wires around I think I was able to get them flush.