Do I need a specific wattage water heater?

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tdsj81

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I'm on the hunt for a new water heater. The problem I'm finding is that most that fit my size need use two separate 4500w heating elements totaling 9000w. My current hot water heater is a kenmore 30 gallon that has been using a SINGLE 3500w universal element. The problem I'm face with now is I don't know if my fuse box is set up to handle the dual 4500w elements. I live in a trailer built around the mid 80's (I'd have to look in the closet at the sticker to find out) And I'm pretty sure this is a 100amp breaker box instead of a 200 amp. I did find a water heater online that uses a 1650w single element but it's 28 gallons. And sometimes when I take a hot bath that extra 2 gallons comes in handy. So I think I explained this all pretty clear. Any advice?
 

hj

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A 1640 watt heater would be 120 v and almost completely inadequate for your use. The dual element heaters only operate one element at a time so if your breaker, AND wires can support the 20 +/- amps, you will be fine. Otherwise you can just screw mew 3550 watt elements into the new heater
 

tdsj81

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OK, Thanks guys. Only other problem I'm trying to figure out now is why I have two separate breakers for the hot water heater on my box. I know you guys can't help with that. At least I don't think. Actaully while I'm typing this I'll run back there and look at the AMP for each breaker. OK back, Took a picture and circled both breakers. one is a 20amp dual breaker? and the other is a single 20 amp breaker. I do know for sure the water heater shuts off when I turn off the dual. Actually now that I think about it I think I have a lose set of wires near the water heater that I taped up about 3 years ago. Might be for the old breaker? Anyway Does that dual breaker I have look to be good enough for the dual 4500 watt elements?
 
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tdsj81

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A 1640 watt heater would be 120 v and almost completely inadequate for your use. The dual element heaters only operate one element at a time so if your breaker, AND wires can support the 20 +/- amps, you will be fine. Otherwise you can just screw mew 3550 watt elements into the new heater
Thanks
 

Jadnashua

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That breaker is designed to provide 240vac at 20A total. It could be used as two 20A 120vac circuits, and if your existing WH runs on 120vac, that may be why one power lead is capped off. A 240vac WH will need that lead, and may not need a neutral. A 20A circuit requires at least 12g wiring, and if you have that, any 240vac-20A device could be attached. Power=volts*amps, so a 240vac circuit can provide a maximum of 240*20, or 4800W. Codes might dictate a lower load, depending on how long it is expected to be on.
 

tdsj81

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That breaker is designed to provide 240vac at 20A total. It could be used as two 20A 120vac circuits, and if your existing WH runs on 120vac, that may be why one power lead is capped off. A 240vac WH will need that lead, and may not need a neutral. A 20A circuit requires at least 12g wiring, and if you have that, any 240vac-20A device could be attached. Power=volts*amps, so a 240vac circuit can provide a maximum of 240*20, or 4800W. Codes might dictate a lower load, depending on how long it is expected to be on.

Thanks, What you said is a little advanced for me. But I do think I mostly understand. And if I understand this is what I've found out about the breaker box by looking closer. The double pole 20 amp breaker is hooked up on both poles. So it looks like it is simply just a 20 amp 240 volt breaker. As far as the wire I'm not sure on yet since I don't have a wire gauge thing to measure the wire. But my guess is like yours that if it's on the 20 amp it's probably 12 gauge. And after looking up the water heaters online they require a 10 gauge with 30 amp breaker. So it doesn't look like I'm in good standing. I do use window AC though since the central air doesn't work so I may look at measuring the wire on that when I go to measure and see if the 30 amp breaker for the central air is 10 gauge. If it is then I can cap off the old 12 gauge wire and replace the 20 amp double pole with a 30 amp instead and be set.
 

Terry

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Most water heaters use dual 30 amp breakers.
With dual 20's I would switch to the 3500 elements.

The top element heats first, then then when the water is warm at the top, it switches to the bottom element.
To get the 240, it's two hots of 120 each which make up the 240.
 

tdsj81

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Most water heaters use dual 30 amp breakers.
With dual 20's I would switch to the 3500 elements.

The top element heats first, then then when the water is warm at the top, it switches to the bottom element.
To get the 240, it's two hots of 120 each which make up the 240.

Thanks, I'd like to keep the 4500's that come in there since I'd be paying for them. But If the wiring doesn't permit then I guess that will have to be my only option of switching them out since I'm not going to rewire the place.
 

Jadnashua

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Bottom line, you have to follow the instructions in the installation manual...if it says it needs a 30A 240 circuit, and you only have 20A available, you can't install it, or you need to put in lower wattage electrical elements. There's an 80% rule for devices that may run long times...a WH where you have lots of serial uses (lots of showers one after the other for example) could need to run continuously, so 80% of 4800 is 3840, which is why Terry mentioned 3500W elements which give it a little bit of leeway. Note that 240vac might actually be less, too, and since power=volts *amps, that 340W difference could be all eaten up if your supply voltage was lower than 240 (it should be within 10% of that).
 
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