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Wiring for 230V boiler

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    Wiring for 230V boiler

    We are preparing to install a 230V, single phase boiler in a commercial building in San Francisco. We have a 208Y/120 panel; do we need a special transformer for 230 or will 2 hots and a neutral work? Thanks.

    #2
    Originally posted by Loretta C View Post
    We are preparing to install a 230V, single phase boiler in a commercial building in San Francisco. We have a 208Y/120 panel; do we need a special transformer for 230 or will 2 hots and a neutral work? Thanks.
    You could use a 208V input, 230V output auto transformer.


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      #3
      Do you understand the implication of running a 230 resistance element @208 volt? Is it really 230 volt or 240 volt. Does it call for 120/240 or 240 volt. There is a difference. Are you trained electrician?

      Comment


        #4
        Originally posted by Loretta C View Post
        We are preparing to install a 230V, single phase boiler in a commercial building in San Francisco. We have a 208Y/120 panel; do we need a special transformer for 230 or will 2 hots and a neutral work? Thanks.
        For the boiler in question there should be an installation manual. With a manufacturers model number you can normally look these up on-line.

        I just looked up a cheap residential boiler that operates on 240V and the say it can be wired at 208V and that the control transformer has a 208V tap. They say that it will have reduced capacity and maybe performance issues (obviously).

        Check the installation manual for the boiler that you have. See what the manufacturer says.

        The best thing to do is to get the right boiler in the first place. It may cost a little more but gets rid of all the confusion and it's easier to install.
        The 95% of people that you can't trust give the other 5% a bad name.

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          #5
          You should not need a neutral, at 208 volts your water may take longer to heat up.
          Rob

          Moderator

          All responses based on the 2017 NEC unless otherwise noted

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            #6
            Thanks guys. First off, don't panic, I'm not doing any of this myself. And no I'm not an electrician, nor do I claim to be one. I'm a chief engineer in a high rise building...
            Boiler contractor is installing the boilers, which state clearly 230 volt single phase. They do not do the electrical, so I'm waiting to hear back from the electrical contractor. We rarely if ever come across 230v equipment in any building I've worked in so I'm not very familiar with it and most of the engineers I've talked to aren't either so I thought I'd see what the options were.

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              #7
              I would contact the boiler contractor and instruct them to provide equipment that operates at 208 volts. They are responsible for being compatible with your building; the building is not responsible for being compatible with their equipment.
              Charles E. Beck, P.E., Seattle
              Comments based on 2017 NEC unless otherwise noted.

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                #8
                Let's say the boiler rating is 6 kW/230 V [Europian 400/√3=231V] single phase.
                At 208 V the power will be only 6*208^2/230^2=4.9 kW.
                If the boiler capacity is 300 l[=300/3.7854=79.25 gallons] and
                neglecting heat losses to ambient [ water from 20oC to 100oC -water heat capacity 4 kJ/liter/oK] the water in this boiler will reach 100oC in 4.45 h for 230 V but for 208 V it will take 5.45h.

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                  #9
                  You are going to have less output, so if units are marginally sized to begin with performance will be even worse with the lower overall watt output.

                  Controls may or may not work depends on what there is for controls, though I'd guess most cases it will still work.
                  I live for today, I'm just a day behind.

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