I’m just finishing up total wiring on our addition and now I’m beginning to look at some very lightweight little minor back-up baseboard heaters. Looks like it is better to go with 240 volt supplies as it draws less electricity. Can I do this through the 12-2wg wires that already are in? Coming off of a receptacle? Or do I have to run new wire from a new breaker? What is the actual working difference between 110 and 240? Wires? Breaker? Both?
Thanks –
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Replies
What size are the heaters in watts? That will help determine what voltage to use.
Remember that you pay the power company for watts (kilowatt-hours, actually) so for a heater of a given size it'll cost the same to operate no matter if it's 120vac or 240vac. The advantage of using 240vac is the heater will draw half as many amps: watts = voltage x current. For larger heaters, this will save you on wire size but for small ones (say 1500 watts or smaller) there's no real advantage.
The nearby receptacle is 120vac, so you obviously can't get 240vac from there, and in any case the heater should have its own circuit breaker. 120vac heaters use a single pole circuit breaker, 240vac use a two pole circuit breaker.
"Looks like it is better to go with 240 volt supplies as it draws less electricity."
Not really.
You are going to draw whatever kw the thermostat demands to keep the space warm (up to the capacity of the heater).
240V heaters are preferred since they require smaller wires for the same amount of total power/heat. They don't really "save" electricity.
You can use essentially the same 2-wire (plus ground) cable for 240V as you use for 120V -- the wire has to be sized to the current, not voltage, and standard AC cable is generally rated to 500V or so. The one detail is that you need cable that is color-coded differently for 240V -- there should be no white, just black and red. But depending on who you believe and how you read the NEC spec, it might be considered OK to change the color of the white by painting the ends (with special wire paint) or wrapping plastic electrical tape around them.
You do need a different breaker for 240 vs 120. The 240V breaker is actually two breakers ganged together, so that you can connect to both sides of the 240V line. There is no neutral connection.
So hold on here. Does all of this mean that I absolutely must come off of a new breaker int he box and cannot come off of a nearby receptacle that is already wired to a 20 amp breaker by way of 12/2wground line? I'm thinkin two small baseboard heaters here; maybe four foot each max. And they are figured at about an amp per foot. The rest of that circuit is just a few lights and such .. no big draws.
So the pic I'm getting here is: 2-pole 20 amp breaker dedicated to these heaters only(?) Or should I just look for 110 amp heaters and come off of a receptacle? I think I had gotten the impression that 220 ACTUALLY used LESS juice! That didn't make sense but that is what is implied here and there.
Whaddayathink?
Hold on here. I've got someone telling me through email that I can just come off of a nearby receptacle and into a 220 heater. The nearby receptacle is wired back to a 20 amp breaker which is for some lights and receptacles in the room. But isn't this wrong? Isn't it true that I CANNOT simply leg off of a receptacle that is wired 12/2wg to a standard breaker?
Nope, unless the "standard receptacle" just happens to be wired on a split 240V circuit (it happens but is not at all common), you cannot wire a 240V heater to the receptacle circuit and have it function properly. There in only 120V available at the receptacle, and you'll only get about 1/4 of the rated heat out of a 240V heater if you attach it to a 120V circuit.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Thank you, I knew that this somehow didn't make sense but I don't know enough to know why. So .. it sounds like I have a choice of either finding a couple of 110 v heaters and then being able to leg off of the receptacles OR putting in a line to the box to a 2-pole breaker. Is this at least closer to correct?
Yes, that would be closer to correct. And if you use an existing circuit you must be careful to not overload it -- you can only put about 1500 watts total on a 15-amp 120V circuit.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
I am not sure, but I think that hardwired heaters need to be on a dedicated circuit..
William the Geezer, the sequel to Billy the Kid - Shoe
One would suspect this is the case.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
sorry to have fragmented this out so much but one last question on this:
would a 110 heater be just as 'efficient' as a 220? In other words, is there any distinct advantage to getting/using a 220?
Thanks!
No difference in efficiency. Burning electricity to heat is 100%.
To back up a bit...why are you having to use backup heaters in a newly constructed addition?
As for the heaters... it's pretty simple. If you buy them with a standard cord attached and they use 120 volts, they are meant to be plugged into a common room outlet. This should cause no problem unless the rest of the circuit is over loaded for some reason.
A 240 volt heater usually must be hardwired to a separate circuit and generally will use more electricity simply because it is a higher watt unit and puts out more heat than a smaller unit. The wire and breaker must be sized to the amp requirement of the heater.
If the space needs #### BTU/hr then then it needs #### BTU/hr. And the operating cost will be the same. The only way that you would save money with the 120 v heater is if it where too small and the room temp dropped.And in the smaller sizes you can get the same hardwired heaters in 120 and 240.And unless there is a UL rule against it there is not reason that you could not get corded 240 heaters other than few people have genral purpose 240 receptacles and thus no market for them.On second thought there might be a few corded 240 volt heaters. 240 volt window AC used to be common in 240 for the larger sizes. And some might have been heat pumps with resistice backup..
William the Geezer, the sequel to Billy the Kid - Shoe
Not pretty to look at , but Northern Tool sells a few "job site" heaters at 220 with a cord. I had considered it for the shop.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
"If Brains was lard, you couldn't grease much of a pan"Jed Clampitt
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...very lightweight little minor back-up baseboard heaters....
A four-foot baseboard heater isn't 'very lightweight little minor...'; two of them in a medium-sized room (10 x 20) can constitute the main heat source, depending on insulation quality and climate of course.
This is new construction; you're not worried about snaking through finished walls, and wire is cheap, so there's no reason not to do it right. Get standard 240v units; run new 12-2 from a double 20A breaker; and don't screw around trying to pull the juice off a receptical. Heaters should be on their own separate circuits. Among other reasons, it makes it a heck of a lot easier to turn them definitely off in the non-heating season without turning off other stuff you want to keep running.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
Edited 8/3/2009 6:58 pm ET by Dinosaur
Need to add a not before the do it right. (;-). That's what happens when your mind is faster than your fingers.For those who have fought for it Freedom has a flavor the protected will never know.
Thanx; got it.
But I think you meant that my fingers are faster than my mind....
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
I was giving you the benefit of the doubt, thinking faster than the fingers could type it.For those who have fought for it Freedom has a flavor the protected will never know.
I used to own a typesetting and graphics studio in NYC. Back when computers where the size of pickup trucks I did almost nothing but type on the first generation of electronic keyboards, anywhere from 8 to 14 hours a day. I got up to about 140 wpm, faster than any mechanical keyboard--including the IBM Selectric, which was the fastest in the world at that time--could accept.
The newer keyboards aren't as good as the old ones; most are cheap and poorly designed and there is no 'dish' in the plane of the keytops. But most people who use computers can't really type at all, so there's no real demand for better keyboards.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
You got that right. I used to have a few old IBM-style keyboards, but one by one they broke down, and now I'm stuck with "soft touch" ones that really suck. And they all have all the "extra" keys that just cause obscene things to happen when you hit them accidentally.You wanna really get POed, you should try using "Rational Software Architect" to enter code. This tool "helps" you by popping up little prompt windows about every third keystroke. But when the windows pop up they sometimes "grab" the cursor and drag it across the screen, highlighting a bunch of text, and then you type some more (since you're typing faster than the computer can think) and erase half of what you've just entered.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
You ever melt and pour lead type? I worked at a place where that was used , mostly on an aging machine that encoded checks that were already printed, the bank code encoding I think...man, the guy that ran that task, was a few cards short of a deck, from the lead fumes I guess.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
"If Brains was lard, you couldn't grease much of a pan"Jed Clampitt
View Image
Nope. Hot lead was dead before I got into the biz, and Linotype was dying.
I got in just after the first generation of $100,000+ photo-typesetters running on mainframe computers gave birth to the smaller, office-computer-based machines with output generated by firing a strobe light through a negative at photo paper. All hardware programmed, too: 8½" floppy disc drive for input storage, but no software. In the back there was a motherboard the size of a Texaco street map, and a rack of plug-in circuit boards about 2' x 4' x 3' deep. Whole thing looked like a very large desk humping a television set that gave birth to a schizophrenic typewriter....
The exposed photo paper was scrolled into a light-tight cassette as it was set, then we cut it off, placed the cassette in a three-tank + dryer photo processing machine about 10 feet long, and waited for the developed paper to come out the other end.
A small system like mine was about $50k + finance charges...and then ya hadda buy the filmstrip negatives at $450 a pop for licensed typefaces;$100 a pop for the knock-offs.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....
I helped my brother wire the keyboard of one such system up to an S-100 computer (via the printer interface, IIRC) to "computerize" the system.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
I was just told by an electrician that if I go with the 240 heater it will be CHEAPER for the SAME amount of heat than if I go with 110. Is this True??? He said that the efficiency of the 240 allows for LESS electricity for the SAME amount of heat. And indeed, on the box that holds the baseboard that I'm looking at it can be hooked up either way and one way it draws 3 or 4 amps and the other way -110- it draws 6 or 8! I don't get this! Will I really be spending more money on the same amount of heat?
Thanks!
3 amps at 240V is the same amount of power as 6 amps at 120V. Power is volts times amps. You pay for the amount of power you use, not the amount of amps.There may be a savings in line losses for the 240V unit in some circumstances, but the difference would be minimal -- probably well below 1%.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Dan and Stuart -
Thanks for the clarification .. the assurance. This guy swore to me that over the years the 240 version of the heater would more than pay for itself ... for the swapping out and replacement of the box that I'd have to do to get more breaker room for the 2-pole 240 -- said that it would literally translate to tangible monitary savings. I STILL don't get why the same little heater can either be set up to draw 3 amps or 6-8 amps for the same operation. I mean, is it hotter faster at 6-8 amps? I donno .. electricity is one of the few things that I just have to shake my head at. People always explain it this way and that as if they have the way to make me eailiy understand . . . but at this point I"m happy to have it remain a sort of black hole in my 'education' -- I can always consult with guys like you who've got a grasp of it!
Thanks -
Some device use 2 120 volt elements. You connect them in parallel for 120 and in series for 240.However, I don't think that baseboard heaters are typically made that way. All of them that I have seen are made for one or the other..
William the Geezer, the sequel to Billy the Kid - Shoe
Hi Newbuilder, I'd like to add to the confusion. :<]In theory, Dan and Stuart are correct.In practice, your electrician is correct.Your electrician knows theory too!Here's why I'm sayin'.While sanding floors for over 25 years we would occasionally work in a house that did not have 220. Our 4 hsp motors could be switched to operate at 110 and so we would switch to whatever voltage we had. Believe me we could tell that we were under powered on 110 and I'm sure that it would add at least an hour to our day. I can't prove it from here anymore but I'd bet that we used more electricity than we would have with the 220 volts. Having the power cord in your hand all day was proof that it was not hot from overloading. If it was mine I'd give the electrician the go ahead.
Your 4HP motors, when switched to 120V mode, must have been set up to run at 2HP, because that's all you can get out of a 20A 120V circuit.Rules of thumb:
A single phase motor at 115V draws 10A per horsepower.
A single phase motor at 230V draws 5A per horsepower.In the OP's situation, his heater is a simple resistive load designed for 120V or 240V, so power consumption should be the same no matter which voltage it runs on. BruceT
But does this mean that the 120 V baseboard will actually put out as much heat as the 240? Or that it will take twice as long to produce the same amount of heat?
Or is it that the 120 draws over twice the amperage in ORDER to produce a similar amount of heat in the same period of time???
I'll have a go at this >>>
Your heater's output and power consumption are both rated in watts.
Your resistive heater converts electricity at 100% efficiency - 1 watt in = 1 watt of heat out.
Your power company sells you electricity by the kilowatt, which is a block of 1000 watts.
Watts = volts x amps. W = V x A
Assume your new heater's output is 1200 watts.
You can get the needed 1200 watts by supplying 10 amps at 120 volts or by supplying 5 amps at 240 volts.
10A x 120V = 1200W and / or 5A x 240V = 1200W
Same amount of watts consumed, same electrical bill at the end of the month.
Way back to your original question - Can you get 240v out of a nearby outlet? No.
Should you install a 240v line for the heaters? I would, but only after determining the size needed via the heater spec plates.
Jim
Never underestimate the value of a sharp pencil or good light.
Edited 8/6/2009 7:54 am ET by JTC1
IF IS IS CONVERTIBLE, YES IT WILL PUT OUT THE SAME AMOUNT OF POWER WIRED FOR 120 AS 240.However, it not common that baseboard heaters are convertible. If you connect a 240 heater to 120 you will get out 1/4 the amount of heat..
William the Geezer, the sequel to Billy the Kid - Shoe
The latter. Same wattage, half the voltage, twice the amperage.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Yes, a 120V heater of a certain wattage rating puts out exactly the same heat per unit of time as a 240V heater of the same wattage rating.Think of the 120V vs 240V comparison as people on a see-saw. Two 120 lb people on one side will balance one 240 lb person on the other.Similarly, 2 amps of electricity at 120V produces the same 240 watts of heat as 1 amp of electricity at 240V. The power company charges you for watt/hours, not volts or amps, so the cost is the same either way.BruceT
Edited 8/7/2009 11:48 am by brucet9
EXcellent!
thanks!
In that case the problem was line losses. Power was being burned by higher resistance losses in the lines and never reaching the motor. It takes only a very small voltage loss to cause considerable power loss in an electric motor.But in the case of a heater, if most of the wires are inside the "envelope", most of your resistive losses in the wires still end up as heat in the house, so there's really very little energy lost.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Your dual voltage heater is actually two heaters, both designed for 120V at 3A. If you hook them up "in parallel" to a 120V line they draw a combined 6A. If you hook them up "in series" (back-to-back) to a 240V line then each still draws 3A, but the total voltage is 240V.
As I stood before the gates I realized that I never want to be as certain about anything as were the people who built this place. --Rabbi Sheila Peltz, on her visit to Auschwitz
Edited 8/6/2009 8:42 am by DanH
The voltage of the heater won't make any difference in how much it costs to run. The power company charges you for kilowatt-hours, not for volts or amps.
Say you have a 1200 watt heater. Watts = volts x amps; you can get a heater that uses 240vac at 5 amps, or 120vac at 10 amps, but in either case the number of watts is the same. Running a 240vac, 1200 watt heater for an hour will cost the same as a 120vac, 1200 watt heater.