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  1. #1
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    DNO requesting split phase install for ASHP



    Hello,

    I'm trying to install an ASHP system into a large detached house built in 1950s.

    After completing the insulation, the heat load of the house was calculated and the system specification is a dual heat pump system comprising of a Diaking Altherma LT 16kw and 8kw heat pump. 16kw for downstairs and 8kw for upstairs. We're planning to use fanned radiators to allow flow temperature of 35-40 degrees.

    All that is just fine, but my installer submitted a request to the DNO and they've come back saying that we need split phase supply installed as the total load will be over 100 Amps. The house currently has a single phase 100A supply.

    I understand that of inrush current for compressors is often high but these systems are inverter controlled and have soft start to limit the inrush. I don't think the DNO are considering this.

    Does this sound reasonable? Has anyone else had this problem?

    Thanks!



  2. #2
    Join Date
    Nov 2006
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    Re: DNO requesting split phase install for ASHP

    the 16 & 8Kw will be the heat output not the electrical input the DNO must not realise this

  3. #3
    Join Date
    Oct 2001
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    Nottingham UK
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    Re: DNO requesting split phase install for ASHP

    Have you added up the electrical heater element loads in addition to the compressor?
    I'm back on the Pale

  4. #4
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    Mar 2001
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    Re: DNO requesting split phase install for ASHP

    Whether inverter or not the house supply needs to be the max current you can draw, is it 3 phase they are suggesting? What do you mean by split phase? Normal house supply here is 63a, is 100a standard domestic supply?
    Mostly found in the southern part of this green and pleasant land.

  5. #5
    Join Date
    Sep 2005
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    UK
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    Re: DNO requesting split phase install for ASHP

    Quote Originally Posted by al View Post
    Whether inverter or not the house supply needs to be the max current you can draw, is it 3 phase they are suggesting? What do you mean by split phase? Normal house supply here is 63a, is 100a standard domestic supply?
    split phase is a bit like 3 phase, but 2 phases 180' out of sync with each other instead of 3 @ 120'

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