New Heating Elements - No Hot Water

So 3 days ago I woke up to no hot water.

We have an electric Richmond water heater.

First thing I did was take the panels off and hit the reset button.

Nothing.

Since it'd been many years since anyone has done any kind of maintenance on it, I decided it had probably been running on one element for a while now, we'd only really get 20 mins of hot water tops in the shower.

So I drain and replace. I don't know how I ended up putting different elements than what came out, some confused advice from a guy at menards, but anyway I took out two discussing 3500w 208v elements and replaced them with a 120v 2000w element on the top, and a 240v 4500w element on the bottom.

After making sure the tank was full I switched back on the electricity and waited for an hour or so, the water was still very cold.

Now this is the embarrassing part, now, and only now was when I checked the fuse, which had blown. I replaced it for an identical one and for the first time (I just learned how to) checked the voltages over the elements. Having one wire grounded and the other either side of both elements it read 120v all 4 times.

Satisfied that it was working, I left it for a while, but still not hot water, not even slightly warm. I have a very basic knowledge of electricity, and DIY in general.

I googled the crap out of everything, but can't seem to find an answer.

Additional info: 40gal tank, we're up in MN so the water is coming in VERY cold. I have a multimeter at hand but don't really know how to use it too well.

Please any advice, the only thing I can think of is having two elements with differing voltages is not making it work?

 

if you have 230 /240 volts coming into the unit, and your top element is 120 volt... what do you think has happened to it.
The top element has to heat the top portion of the tank or that aquastat will not satisfy and heat the lower portion of the tank.
Sounds like you have blown the top element, and it will never switch to the bottom unless you change the element (or bypass the top thermostat).

 

Wrong element, you need a 240v element in both locations.

 

Agreed... same element top AND bottom... you've burned out the top element by applying twice it's rated voltage to it.

Moving your post from home heating forum to water heater forum.....

 

Is there any way I can bypass the upper element to see the bottom one working correctly? When I measure the voltage it does only have 120v going across it.

 

Also I measured the residence across it and it read 7-8 ohms, which is lower than the other one which was at 16ish. But i'd expect that with it being much smaller, does that mean it's working or burned out?

 

Does the nameplate on your heater say 240 volts or does it say 120/240 volts? In addition to ground do you have two or three wires connected to the water heater? Is the breaker a single pole breaker or double pole breaker?

 

It says 240/208v. The elements I took out were 208v and they seemed to last a long time. The breaker has two fuses, they're old style cartridge fuses in a multi fuse holder.

Not sure about the wires, there only seems to be one coming out of the fuse box into the heater, but it's pretty chunk and wide.

 

Replaced the 120v with a 240v 4500w. Replaced fuse again... could the 120v element caused the fuse to blow?

 

Also, the heater did hum for a few seconds after turning it on, then it stopped. Still seeing 120v across both elements.

Any more suggestions?

 

In the pic below....... are you measuring across the screw terminals of the element ?
You should see 240 volts on the top element.....if the tank is cold.

 

I only get 120v. Never anything higher. But that's measuring one side against earth. Not across them both.

 

Just measured across the two screws of the element, reads 0 volts.

 

One fuse has gone out of the two that are together. How come the water heater still have a voltage when one of the fuses has gone?!

 

The water heater runs on 240 volts. That is both legs of your house service. Each leg measures 120 volts to neutral or ground. So you need both fuses to be good to get 240 volts.

If one fuse is open......you'll see only 120 volts.

 

Thanks PJ, but won't the system run at 120 volts? If not why not? And do you have any idea why one fuse keeps blowing but not the other? I did hear a hum for about 10 seconds, then I assume the fuse went.

 

Each side of the 240 volts to ground is 120 volts. You still have one side hot if one fuse is good.

Tech note: You replied: That's a cable not a wire. Can get very confusing if you call cables wires. A wire is a single conductor. A cable is two or more wires in a metallic or non-metallic sheath.

No because you are not reading 120 volts between the two conductors. You are reading 120 volts to ground. Ground is not part of the normal circuit.

 

I don't know why you are blowing a fuse. It would suggest a shorted element or possibly the upper thermostat was damaged and now both element are coming on at the same time..

 

Thanks Ray you cleared a lot of that up.

So my question now is what is causing one of the fuses to go a few seconds into operation?

Should I replace both thermostats, or just the top one? (I'm assuming since the top element heats up first, it can't be the bottom one causing the problem).

 

Thanks PJ, I think I might go ahead and replace the upper thermostat and see what happens. I assume they don't need any special tools? Also need to buy more fuses, do places still carry old cartridge fuses?

 

Some additional info, it did run for about 10 seconds, then the fuse blew again. What does that tell me if it didn't blow instantly, but after a short period of time? Also, the elements are brand new, thermostats could be up to 15 years old.

A

 

Thanks everyone who posted in this thread it means a lot to me! Water heater is now working, I guess the upper thermostat was blowing out the fuse for some reason, it looks fine. Replaced it and now it's going good.

Thanks again, great resource you have here, certainly saved me money on a plummer!

Thanks

 

Hard to tell the condition of a thermostat by a visual check. Apparently it was shorted internally.... probably allowing both elements to be connected at the same time.

Good job

 

Many fuses are designed to handle an inrush of current above their rating for a few seconds so that motors etc. can start however once the built in time delay is exceeded they will blow.

Is your whole house on fuses not breakers or are the fuses in a panel the runs off a breaker in a breaker panel?

 

It's 100% fuses. With a 'last inspected 1967' sticker on it. Most of them are the round screw in types with little plastic windows on them.

 

Just checking. Good you got it. You did replace the 120v element with a 240v element didn't you?

 

I did! 120v one was only $6 so not really a big loss.

 

Fuse blew again after a couple of days.

Is it possible that the fuses aren't right for the system? I have two 20amp fuses in there for a 4500w/240v system.

Should they be 30amp's?

 

Yes......you should be using two 30 amp fuses.

The current draw on the water heater is around 19 amps which is too much of a continuous load on a 20 amp fuse.

 

Was it established the wiring was 10 gauge. It must be if you use 30 amp fuses.

 

Ray has an excellent point and looking back at your first post...... you had 3500 watt elements in your water heater when you started the repair process. Now you have 4500 watt elements.

That would explain why you had 20 amp fuses as the original current draw was around 15 amps.

 

So should I replace both the fuses with 25 amp fuses? Or 30 amp fuses? Is there any danger in doing this, I still want the fuses to blow instead of... well me if something were to go wrong.

 

To use any fuse larger than 20 amps you must have #10 or larger wire. If you have number 12 or smaller there is a danger of fire if you use anything larger then a 20 amp fuse. (Or 15 amp fuse if #14 wire)

 

All wiring has a current rating it can handle.
# 12 wiring is rated for 20 amps maximum.
# 10 wiring is rated for 30 amps maximum.

You can't increase the size of the protective device over the capabilities of the wire.

Like Ray said previously....you'll need to determine the size of the wire. If it is NonMetallic type.....the size will be printed on the jacket. Metal clad types are a bit tougher to determine the gauge.
Since you have fuses there I'm figuring you'll have metal clad or BX type wiring.
You will need to compare it with another 20 or 30 amp circuit in the panel.

As an electrician we can usually tell the gauge of a wire just looking at it ..... not very helpful in your case.





(fast fingers Ray got me)

 

This has become an electrical issue so I have moved it to Electrical Forum.

Go to a hardware store and buy one foot of #14, #12, and #10 solid (not stranded) THHN/THWN. When you get home strip off an inch or so of the insulation on the three wires. Compare the bare copper in each wire to the bare copper potion of the wire connected to the fuses.

If you have a wire stripper you can also try comparing to the holes for stripping.

A wire gauge is of course best but may be the most expensive way if you don't own one. If you don't have a stripper the wire samples are cheapest. If you have a buying history with the hardware store They may be willing to give you short lengths of scrap wire for free.

 

"As an electrician we can usually tell the gauge of a wire just looking at it ..... not very helpful in your case."

Does that mean if I take a picture of the cable or the wiring you could tell me?

 

No. Look on the jacket of a cable or the insulation of a wire. The size may be imprinted there.

 

"e gcc-k romex 10/2 with ground type nm-b" appears to be the only relevant info i could see on the cable.

 

And that was the info we needed. You can use 30 amp fuses.

 

Excellent, I'll wait for the 20amp ones to go again then I'll switch.

Thanks for all your help!