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Hot water heater on 208 vac?

Discussion in 'Electronic Design' started by Esther & Fester Bestertester, Jan 29, 2007.

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  1. I've got a 240 v. electric water heater and a need for a 208 v (single-phase)
    one.

    What's the down-side of using this heater on 208 vac? Is lower temperature
    all I have to be concerned about?

    FBt
     
  2. Water heaters are normally thermostatically controlled.
    The downside is that it will run at 75% of rated power,
    and therefore take 33% longer to get up to temperature.
    The upside is that the electrical parts will probably
    last longer than they would at 240V.
     
  3. Another thing to check is that there isn't any other type
    of load other than the heater. For example, if there's a
    relay/contactor anywhere performing the high current
    switching, or a timeswitch, these items may not work
    properly on reduced voltage.
     
  4. No, with less power it will take longer to recover so your available
    gallons/liters of hot water at a given temperature over a given period
    of time will be much less.

    Just swap the element assembly out, it's usually not a big deal-- they
    are maintenance items.


    Best regards,
    Spehro Pefhany
     
  5. jasen

    jasen Guest

    Slower heating more like,

    If the themostat still works the final temperature
    will be the same.
     
  6. But since the heating is proportional to power and voltage squared, you
    only have 2/3 of the heating, NOT 240/208ths.

    --
    Many thanks,

    Don Lancaster voice phone: (928)428-4073
    Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
    rss: http://www.tinaja.com/whtnu.xml email:

    Please visit my GURU's LAIR web site at http://www.tinaja.com
     
  7. Don Kelly

    Don Kelly Guest

    ----------------------------
     
  8. quietguy

    quietguy Guest

    For the last 14 years my (240v) HW system has run on voltages from around 205 to
    220 due to a lousy elecricity supply - 1st HW heater lasted 9 years, (bad water
    too) and the replacement is still going strong.

    David - who gets really annoyed when the volts drop so low his microwave can
    hardly boil water
     
  9. message
    You could add a boost transformer for the microwave - 240 to 24.

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  10. If your "lousy electrcity supply" is due to the public utility, scream
    until they respond and fix it. However if the voltage drop is inside
    your residence, call an electrician immediately and turn off the water
    heater or keep the phone number of the fire department nearby.
    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
     
  11. quietguy

    quietguy Guest

    Thanks for the warning, but it is to do with the external supply - 400+ metres from
    the tranny to my house results in a big drop when any heavy loads are on. I've been
    complaining for years but their solution is for me to pay for a new pole nearer to
    the house on which they will mount the tranny - but I will not wear that so I am
    still working on them to do it FOC

    David - who doesn't give up too easy
     
  12. ? "quietguy" <> ??????
    ??? ??????
    Yes, but is 400 m too far away?
    220 volts->max.1km (low voltage)
    15kV->max 60 km (medium voltage)
    150 kV->max 220 km?(high voltage)
    400 kV->max 500 km?(extra high voltage)
    There are also power limitations-due to wire gauge (in LV) and in MV,in HV
    there are propagation and stability isssues.Has your utility checked your
    neutral connection?
     
  13. Guest

    | Thanks for the warning, but it is to do with the external supply - 400+ metres from
    | the tranny to my house results in a big drop when any heavy loads are on. I've been
    | complaining for years but their solution is for me to pay for a new pole nearer to
    | the house on which they will mount the tranny - but I will not wear that so I am
    | still working on them to do it FOC

    Add a 2nd tranny at the original pole and wire in series to get double the
    voltage. Add a dry tranny at the house to drop the voltage back down to
    normal. You'll get 1/4 the voltage drop that way. Just make sure the
    service drop wires can handle the double voltage (most can go to 600V).
     
  14. Kind of hard to beleive that it is 400M to nearest pole. Are you on a
    mid-span tap? I was able to convince FP&L to add a pole and avoid a
    midspan tap. They wanted me to run the drop across the property
    diagnally to still another pole and that would have precluded having a
    raised deck and a pool due to clearances. I talked them into it.
    Dropping a pole is not a huge expense. In your case they are providing
    you poorly regulated service. You should make a stink.

    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
     
  15. John Gilmer

    John Gilmer Guest

    message
    Gad!

    I thought I had a long run (440') but you have me beat by a factor of three.

    (BTW: I never had problems with "droop" yet the power company (after
    several failures of the underground feed) installed a new drop with much
    larger cables. (Don't know the numbers.)
     
  16. quietguy

    quietguy Guest

    Thanks for the ideas but i am not prepared to pay to have this fixed - I didn't choose to have the
    xformer where it is, and I didn't select the wire gauge etc. As southern elect made those (wrong)
    choices I reckon they can damn well fix it at their cost

    David
     
  17. quietguy

    quietguy Guest

    Well no. I have a pole near the house, another pole about 30 metres away which houses the elec meters
    etc, then the line goes from that pole 400metres to a xformer on a pole near the roadway.

    I had the line from the meter-containing-pole to the house upgraded when I installed an offpeak HWS, and
    had a new switchboard etc installed at that time

    David
    Nope - the line just comes from the pole near the road to my house.

    David
     
  18. Can't they install a High Voltage step down transformer on the closest
    pole and extend HV to it from the pole further away?
    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
     
  19. quietguy

    quietguy Guest

    Yep, if I remember correctly (and there is lots of doubt about that
    these days) one electricity guy suggested that some time ago - but said
    I would have to pay for the new poles - bugger that I reckon

    David

    PS: I do however wonder about the wisdom of extending high voltage lines
    across a farm - even with the 240v lines some guys kill themselves when
    they forget to check overhead when using tip trucks, augers etc.

    But perhaps it wouldn't be any more of a hazard - any views on this?
     
  20. message
    IIRC they have to be run higher by code.


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