dump load heating element

mahendra
mahendra Solar Expert Posts: 188 ✭✭✭
in General Solar Power Topics #1
hi. where can i pick up a good heating element/water heating element to act as a dump load for my charge controllers
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #2
    Re: dump load heating element

    What voltage and power rating(s) are you looking for?

    Will these be air or water based (i.e., dump heat into a water heater for example)?

    In the "olden days", people would make electric heaters out of nichrome wire and ceramic supports.

    What do you have available in your region--Old power resistors used to be pretty common (lots of old power systems, motor controllers, etc. had big ceramic power resistors). Today with modern electronic motor controllers and switching power supplies (and interest in not wasting power), I have not seen many of these types of power resistors in surplus/scrap bins anymore.

    Search in Google for Power Resistors and click on "Images for Power Resistors" to see the styles commonly available.

    Power = Voltage * Current = V2/R = I2R

    If you find a 120 VAC electric heater at 1,500 watts, you can run it at 60 volts (AC or DC) and it will dissipate ~375 watts (note heaters have limit switches that open if the heater gets too hot--I am not sure how well those limit switches will work on DC current (the limit switches may strike an arc and not turn off if heater overheats, etc.).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • mahendra
    mahendra Solar Expert Posts: 188 ✭✭✭
    #3
    Re: dump load heating element

    ok i was hoping a dc heating element for water heating
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
    Re: dump load heating element
    mahendra wrote: »
    ok i was hoping a dc heating element for water heating

    There's really no such thing as a "DC heating element"; it's just a resistor and it doesn't care whether it gets AC or DC. The same is not true of control circuits such as thermostats however.
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,613 admin
    #5
    Re: dump load heating element

    You can get different water heater wattage (and voltage) elements from the local hardware store...

    But, again, need to know your wattage/amperage/voltage you will need.

    A 3,500 Watt element 240 volts will run at 60 volts (somewhere around $10-$20 each):

    Power = 3,500 watts * (60 volts / 240 volt rated)2 = 219 watts

    There are some semi-custom heating elements designed to run more power at lower voltages--But they are not cheap.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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