If things are currently connected to deliver 120 v, you can use the white as a hot by making the move from the neutral bar to the other hot on the 2-pole breaker. I forget how you mark the white, but I am thinking Sharpie at each end, or black tape at each end.
120v Tank Connected to 30A Dbl Brk
- Thread starter Bruce Dew
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Well checked the box just now and I screwed up again, not a 30 dbl but 20 dbl (had on my glasses) and the on/off dbl pol says 30a 208-277v on it. So now what to do; First change to 30 dbl breaker and connect white to second leg for 240 tank or just buy another 120v tank. At a crossroads.
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If I go with 240v tank then need 30amp breaker
the wire is already there, don't need new wire
I think you are saying the #10 wire is already there. So should be easy to swap in the new WH powered by a 30 amp breaker..
Consider a hybrid WH that uses a heat pump primarily, and resistance heating when the heat pump is not enough. Costs more to buy. Uses less electricity. Cools and dehumidifies the area around it. Requires a condensation drain, which could run outdoors.
Jadnashua
Retired Defense Industry Engineer xxx
Just to be clear, you need to verify what gauge wire is there...while that can be heavier gauge than you need, it must be at least the minimum required for the breaker you utilize. 12g wire is fine for a 20A circuit, but not for a 30A one. On most wire you might have, it would be suitable for 120 or 240vac use.
Yea, I'm really screwed up now. I found the manual and my receipt from lowes, it says 30 gal with 3000w single element element. The install say can use 20 breaker to 4000w on 10 ga and 3500 on 12 gauge but I think it 10 ga but can't find size on wire to make sure. I'm going to do a lot more research but know it 18 yrs old and need to get replaced soon before it starts to leak. Can't believe it only cost 148 in 2004 compared to todays prices.
OK so let me ask this, if this unit used 3800w element at 240 but is only connected to 120v, u actually would only be getting 1/4 that much heating wattage, right. So if I buy a 30 gal that uses 2000w at 120v I would be getting faster heat up, right.
wwhitney
In the Trades
Yes, assuming the element is a fixed resistance. If the resistance varies with temperature, there will be some second order effects.
Cheers, Wayne
The 1 I bought in 2004 was single element 3800w at 240v but sold as 120v unit and was installed as 120v best I can tell.
Here's mdl number from whirlpool, MHE1F30H5035V AND LOWES NUMBER140401
wwhitney
In the Trades
I didn't mean to imply any uncertainty, I was being excessively theoretically precise. For practical purposes, if you take a 240V electrical resistance heater and supply it with 120V, you'll get 1/4 the power.
Cheers, Wayne
Cheers, Wayne
So the replacement 120v they have with 2000w at 120 should be faster, right. New update: got 240 + coming off the 20dbl breaker, 120+ each leg; so if not reaching the heater 1 leg must be disconnected (at dbl pole switch), right. Wire is definitely same size as elec dryer wire so must be 10/2, only difference is the dryer has blk and red connected to breaker. Next thing I will remove tape from connections to see what is coming thru to tank. Will update.
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wwhitney
In the Trades
Yes, 2000W > 3800W / 4, so if all your info is correct, it will be over twice as fast to recover.
Wayne
My last observation is that this unit is single 3500w 240v. There is a red wire and black wire that are both showing 124v on meter. So why would it be using only a single element unit when 240v is avail? Is it due to breaker only being 20 amp or the wire, but wire appears to be 10/2; same size wire as going to dryer that is on a 30 amp breaker. Just change breaker and put in dual element unit?
Or just put back this that matches everything there except has little bigger element:
A.O. Smith Signature 100 30-Gallon Tall 6-year Limited Warranty 4500-Watt 1 Element Electric Water Heater
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wwhitney
In the Trades
Voltage measurements are taken between two points, and reporting of voltage should specify both points.
If you want to know if you can install a 240V water heater, you need to check the black-red voltage to see if it's 240V or 0V.
How about a picture of the circuit breaker that controls this circuit, and whatever junction box near the water heater you are taking voltage measurements at?
Cheers, Wayne
If you want to know if you can install a 240V water heater, you need to check the black-red voltage to see if it's 240V or 0V.
How about a picture of the circuit breaker that controls this circuit, and whatever junction box near the water heater you are taking voltage measurements at?
Cheers, Wayne
took reading at panel, and at element and both legs have 124v + or - coming thru; 20 amp dbl breaker is a 20amp dbl breaker, pic will not change that fact
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