Re: Water heater question

I agree with you under that scenario, but if the heating end was to short I
think it would trip the breaker and not heat, and if it were to long, it
wouldn't heat enough to overheat



"Jeff Wisnia" <jwisnia@xxxxxxxxxxxxxx> wrote in message
news:utidnXvT5eZd0ZjbnZ2dnUVZ_tmknZ2d@xxxxxxxxxxxxxx
RBM wrote:

Personally, I don't think the heating element could get hot enough on 120
volt to cause the high limit to trip


I, on the other hand, think it could. I'm not sure you considered the
excellent thermal insulation in modern water heaters.

Let's suppose it's a 4500 watt element and the short to ground occurs
eggsackly in the middle of the heater. Then, 120 volts (from the side of
the 240 the thermostat's not switching) is connected across half the
element and would dissipate half the normal power, 2250 watts.

Given the very effective insulation on modern water heaters, if no one is
drawing hot water, that much power continuously inputted will keep raising
the temperature.

If the short to ground isn't right in the center of the element, but
closer to the unswitched end, then the power dissipated could be even
higher than 2250 watts, until something lets go.

I'm not about to set up an experiment to prove it, but I'd bet a nickle
I'm right about what I just wrote...

Jeff

--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.98*10^14 fathoms per fortnight.


.

Relevant Pages

  • Re: OT: CRTs vs. HDTVs (etc!); was Black Friday: After midnight?!?
    ... who's learnedplasma TVs generate a lot of heat?! ... appliance more than half the wattage consumed is converted to heat. ... for my new 26" Vizio say power consumption is 43 watts. ...
    (rec.food.cooking)
  • Re: Question for electric brewers
    ... brewers boil on full power with 220V, ... Once your wort is boiling (and not counting heat loss trough the sides of your kettel which will vary with ambient temp, material, and size and shape), 4500 watts should evaporate 2 ml of water per second. ...
    (rec.crafts.brewing)
  • Re: OT: CRTs vs. HDTVs (etc!); was Black Friday: After midnight?!?
    ... who's learnedplasma TVs generate a lot of heat?! ... appliance more than half the wattage consumed is converted to heat. ... for my new 26" Vizio say power consumption is 43 watts. ...
    (rec.food.cooking)
  • Re: Watts/Heat relationship (dumb question)
    ... If you measure watts to be equal then you are correct ... except for the power factor which is (Power = E x I x Cos of the angle ... if they all converted exactly the same amount of energy into ... > turned mostly into heat ...
    (sci.electronics.basics)
  • Re: Bollocks: Call to scrap TV standby buttons to help environment
    ... my house is permanently using at least 89 watts. ... and that all the heat they generate is immediately lost to the ... year on permanent 24 hour standby. ... A kilowatt-hour of electricity costs ...
    (uk.media.tv.misc)