LONG STORY: I live in a single-wide from ~1968. We moved out for a few years, and when we moved back in the water heated didn't work any more. The original plumbing was polybutylene. I had tons of problems with it, leaks everywhere, and decided to replace the entire system, since it's only a couple sinks, a tub, and a toilet. So I've replaced the entire system with PVC and CPVC, put a new element in the water heater, and still don't have hot water. I've checked the thermostat and it seems perfectly fine, I get 240v all the way across it, from both sides to the element. The element is band new, never had power to it until water was flowing from the hot side of the sink.

SHORT STORY: Water heater isn't working. It's old and has a brand new element. The cold comes in at the bottom on the side, hot goes out on the top on the side. Nothing on top. Thermostat and element check out perfect, and getting 240v to it



That was the general impression that I got.
Here is my hypothesis. One half of one of your main breakers is either tripped off or is defective. That breaker could be the one in your breaker box, the one in the disconnect on the pole or the breaker in the transformer. It could be tripped from over load, voltage spike or lightening strike during the time the house was unoccupied.

Normally this would show up as the half of your lights and appliances not working. But the side that is working is back feeding through the water heater and any other 240 appliance that is on but not working and is energizing the other side of the panel.
Do voltage check of incoming line lugs with main breaker off. If my hypothesis is correct you will get 120 volts to ground on each lug and 240 across lugs if it is the main breaker in breaker panel. You will get 120 to ground on one lug and 0 on the other lug if it is the breaker in disconnect or transformer breaker.
If you did the voltage check with main breaker in breaker panel on and the breaker in disconnect is at fault, you are getting reading that is a back circuit through water heater. That would explain the 6 volt difference. The 6 volts being the voltage drop across the heating element.
If you get 240 volts across main lugs and get 6 volts across the terminals of water heater breaker, then water heater breaker is faulty. Confirm that by removing breaker and doing voltage check between buss bar contacts.

I'll have to do it tomorrow when it's light out. There are no street lights or anything out here so it's way too dark to safely do anything with the main off at night. Plus my 4 year old would freak out. I'm going to do this first thing tomorrow and report back. Thanks by the way for all your help so far

Sorry for the multiple posts but I'm pretty certain I've found the problem. At the pole the main 100a breaker reads 120v to ground on each side, AND reads 250v across L1 and L2. The buss bar though, only half the poles are hot. So it's like you said, one side is bad, but the power is back feeding through to the house. The problem has to be the main breaker. I checked the bolts where it hooks to the buss bar and the same thing, one side reads 240 and the other reads 0 (with the breakers on).

Only problem now is that the main is tied in to the transformer, so I'm going to have to get the power company to come shut off the power for a few minutes so I can change out the breaker

You should have a drain valve. Open it briefly to insure that the water is indeed not getting hot.

Do another voltage check at the heating element. You should have 120 volts between each terminal and the ground. You should have 240 volts between the two terminals of heating element. (I know you said you did a voltage check but do it again).

If voltage checks out OK, turn off power, remove wires from heating element and do a continuity check between terminals of heating element. Meter should show resistance but should show continuity.

If continuity checks out, using a clamp on amp probe, check amperage on wires to heating element. If you do not have amp probe, using jumper wires, connect heating element directly to incoming power. You could have poor electrical connection, or corroded points in thermostat or over temperature device that is passing voltage but limiting current flow. Do this temporarily, only long enough to see if heating element is getting proper amperage and heats up.

There is a red button on the top thermostat. Press it and see if that helps. Let me know if it works. Good luck, Tom

Tom, the red reset button was not popped out, I tried.

Harold, drain valve gave cold water. Had 120v across each element screw to ground, but only like 7 volts across the two screws. Continuity checked out, gave 16 ohms, which is right on for 240v and 3800w. L1 and L2 were a little rusty looking so I cut them and stripped them back until they were shiny and clean, and hooked them directly to the element. That's been going about 5 minutes now, waiting to let it heat up a bit (if it will).

UPDATE: After about 30 minutes of the lines being hooked directly to the element, there's still no hot water. The element is literally brand new, it's only had power to it like twice (the tank was always full first).

Check wiring at panel, sounds like you have a 120 volt water heater and a 240 volt element. Check wiring and specs on water heater tag. Unhook wiring from element and check each wire to ground. One wire is probably a neutral with no voltage. Water heater breaker is probably a single breaker, not double.

The data plate on the water heater says 240v, and there are two 120v lines coming into it. Each one reads 120v back to ground

Check panel wiring. A voltage check across terminals should read 240. Breaker should be a double breaker. Perhaps someone wired two 120 lines but put on same phase. That can't happen with double breaker.

It is a double pole breaker, yes. When switched on, it reads ~6 volts across the breaker's screws. Each screw reads 120v to the neutral/ground bar. I had read somewhere about having 1 120 line split in two like that, and the main coming into the box is a red 120v, black 120v, and the white neutral/ground.

All of this said, the same wiring used to work perfectly. A little back story, we moved out of here and were gone about 5 years and moved back in. In this time a water line has burst and my wife's uncle came by and shut off the water for us. At this time he also switched off the breaker to the water heater. Since then it doesn't work anymore

Disconnect incoming power wires and check voltage between wires. Of course should read 240 volts.

This is a 240 volt circuit, no neutral. Don't know why someone would run 3-wire cable. Black and red should be hots. White should be unused.


breaker's screws

Did you mean element screws?

When switched on, it reads ~6 volts across the breaker's screws. Each screw reads 120v to the neutral/ground bar. I had read somewhere about having 1 120 line split in two like that, and the main coming into the box is a red 120v, black 120v, and the white neutral/ground.

Am I misreading? Are you speaking of breaker panel?

Yeah sorry. I thought you meant to check the power at the breaker. So panel means where the power comes into the water heater, got it. At the panel yes, power lines read 120v back to ground and ~6v across each other

You have power supply problem if you have only 6 volts across terminals of double breaker and yet have 120 volts to ground from each terminal. Check voltage between incoming power lines to breaker panel.

I'm not at home right now, but I checked the incoming mains while I had the breaker box open. They both read 120 to ground and ~6 across each other.

Then you have power supply problem. You can do a voltage check at disconnect on pole but be very careful. You will be grounded and can be dangerous. If possible find a dry piece of wood or some other non-conductive material to stand on.
Someone may have mis-wired disconnect or may be problem from power company.
If you find same voltages, 120 to ground and only 6 volts across oncoming terminals, call power company.

My background is in household electrical and hvac/r, I'll check it and be careful about it :) I'm just not experienced with mains and such. So this would've had to have happened while the power was turned off to the water heater? Since it worked, then when I turned the breaker back on it didn't work. Is this something that would just happen over time?

Since it worked, then when I turned the breaker back on it didn't work. Is this something that would just happen over time?
Don't understand that statement.

Don't understand that statement.

The water heater used to work fine. Then it was turned off at the breaker. When the breaker was turned back on the water heater no longer worked. So if the problem is in the power line it would have to have happened over time while the breaker was turned off

How long ago was that? How long was the breakers turn off? That also indicates that the problem is electrical and not water heater.

When you did voltage check of the main lines into the breaker panel, was the main breaker on or off?

Do you have any other 240 appliances other than the water heater?

We moved out 5 years ago, the breaker was off for probably a year or two. When I checked the main lines in the main breaker was on. And no, the water heater is the only 240

With the main off, I get 120v from black to ground, and no reading at all from red to ground. So I need to go check the breakers at the disconnect. What am I looking for there?

Well that's progress.

Power company came out this afternoon and let me change out the main breaker. We now have hot water. Thank you so much for all your help

You are welcome.
Time for a hot, hot shower.

Thinkin' someone owes Harold a pizza and a beer... ;)

Thinkin' someone owes Harold a pizza and a beer... ;)

Agreed!