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  1. #27
    Join Date
    Jul 2010
    Location
    SE Texas
    Posts
    122
    Quote Originally Posted by beenthere View Post
    A 5KW rated single phase heater draws between 18 and 22 amps depending on supply voltage at that location.

    I work on them.

    240 volt 5KW=20.83 amps
    240 volt 10KW=41.67 amps
    240 volt 15KW=62.5 amps

    Of course, very few places have exactly 240 volts. And the heaters resistance will change slightly with the temp of the heater as it varies with air flow. So the amp draw will change also.
    Yes,you are completely correct. I apologize for my shortness in my prior post. 20A per 5kw, not 10 kw. And I did mean W1 and W2. Long day at work with some very ignorant customers. Not an excuse however for my rudeness.

  2. #28
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,103
    Quote Originally Posted by ThirdCoastAC View Post
    Yes,you are completely correct. I apologize for my shortness in my prior post. 20A per 5kw, not 10 kw. And I did mean W1 and W2. Long day at work with some very ignorant customers. Not an excuse however for my rudeness.
    We all have bad days from time to tome. Sometimes you gotta step away from the keyboard for a minute or so before posting.

    Some days I take my own advise.
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  3. #29
    Join Date
    Jan 2010
    Posts
    6,320
    Wow...........I was beginning to question my knowledge of electric but then i did the math. As stated Ohm's law and between 210-240 volts 41.66-47.61 amp difference.

    I read his first post on that and let it go. And as usual you guys would not let it ride. Constant policing here. But thats a good thing. Keep everyone in check.
    Good job westval !

  4. #30
    Join Date
    Jun 2010
    Location
    Western Nebraska
    Posts
    246
    Quote Originally Posted by VTP99 View Post
    Wow...........I was beginning to question my knowledge of electric but then i did the math. As stated Ohm's law and between 210-240 volts 41.66-47.61 amp difference.

    I read his first post on that and let it go. And as usual you guys would not let it ride. Constant policing here. But thats a good thing. Keep everyone in check.
    Good job westval !
    Not looking to keep anyone in check, just thinking outloud through the keyboard!......during heating season that's the only time I get to stop and think.....

  5. #31
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,292
    If there is enough amperage to the air handler you could let the thermostat use 10KW for AUX heat and use the other 5KW for defrost. Most air handlers just need a simple wiring change to set them up that way, connect W1 to the thermostat, W2 to the white/defrost from the condenser. If the heat pump can't keep up then only 10KW of heat would be added instead of the full 15KW. If the temp dips too much with only 5KW in defrost the thermostat will bring on the 10KW aux heat for a total of 15KW. Wiring this way has some potential to save some $$$ in defrost at the expense of cooler air from the registers.

  6. #32
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,103
    Old thread, closed as too many previous posters are not Pro * members.
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