I'm planning to purchase a steam shower for my master bathoom and have been doing some serious research, but I'm still hesitating between a
110V unit and 220V unit. The 110V is certainly more convenient, but it's not ETL or UL certified. THe 220V is ETL certified but I heard that it's very costly to run. What shall i do?At this point you are not comparing apples to apples. If these units were fundamentally the same, they would cost the same to run. It sounds like the one unit has a larger heater, which if nothing else would produce more steam, faster
The cost to run the devices depends on how much power they use, not what voltage they run on so Watts is the value to compare. And don't forget that the efficiency of the device in turning water into steam will make a huge difference in how you will use and enjoy using it - a unit which uses little power can, by definition, make less steam (assuming that they are both designed for optimum performance). The power does not depend on the voltage -- you can develop 3000W from either voltage, it just becomes less practical to obtain higher power from the low voltage source with 3600W being the practical upper limit. Will you enjoy a "steam shower" as much if you need to turn it on an hour before using it and find that it never gets more than tepid inside? An underpowered unit could well do that for you.
Personally, I'd go for something in the high-power end of the range whether it be 120V or 240V since it is not likely that it will be used all that many hours a month. Find out exactly how much your utility charges for power. Then do the math for various power levels and you will know how much every minute will cost you and you can then make a rational decision.
Let me add that the total power/cost of operation per minute of use is based, as you note, by the watts. Assuming the unit does not cycle on and off during use, then the total watts can be computed by multiplying the amps by the volts. A 10 amp 240 volt unit will provide the same heat as a 20 amp
120 volt unit.Note a 240 unit will be very slightly more efficient overall, but not enough to bother with.
The voltage is not going to determine the cost to run. Thats determined by the wattage. A higher wattage unit may be 220V for other reasons though.
220V is used so you can use smaller wiring in the walls. So instead of getting even bigger wire when you go to the high wattage, you get a higher voltage unit, then you can maintain the same gauge wire with the higher wattage.A 220v machine will always be a little more efficient than a 110v one.
And, in addition to being easier on the wires, 220/240 inherently balances the load lines coming into the house. It is possible, with numerous large 120 V devices, to load only one leg coming into the house, unless you explicitly balance stuff. I deal with this all the time. :(
With 220/240, you don't have to worry about it.
Always go 220/240 when possible. Whenever possible, I rewire motors from
110 to 220.In some cases, 220 just isn't readily available in some parts of a house. Then, yer stuck w/ 110/120
The other advantage to going with the 240V unit is that, assuming it's rated more or less the same kW as the 120V unit, it will draw less current, and you can use smaller-gauge wire (code permitting, of course), which will be less expensive. Copper wire ain't cheap these days.
Yours aye, W. Underhill
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