replacing a danfoss fp715 with a fp720 ?

Discussion in 'Plumbing and Central Heating' started by JimDr, 30 Nov 2021.

  1. JimDr

    JimDr

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    Hi guys, need some help, my fp715 is u/s (its 23 years old) looks like i need a fp720 to replace it my concern is the rewiring my 715 has L and N then 2 blank connectors then 2 x red and 2 x black in the CH on and HW on ( or vice versa dont want to remove it again at mo as i have just manged to get some hot water on) see pic...will it be obvious which terminals to use on the 720..th
     

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  2. stem

    stem

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    That's an industry standard backplate, so you don't necessarily have to have another Danfoss programmer, unless you want to. In fact it might be easier if you do choose something else. I haven't fitted a FP720, but the advice is that if you are changing from its predecessor the FP715SI you will need to rewire it using the new back plate provided as the FP720 will not fit onto an existing FP715SI back plate. However it shouldn't be difficult as the wires will go to the terminals of the new programmer that have exactly the same functions as the existing one.

    The terminals used will depend on the design of plumbing system that it is controlling. Yours is commensurate with very many in the UK. Some do have a connection to terminal 1 others, like yours don't need it. None, (with a few very rare exceptions, normally old installations) have a connection to terminal 2.

    I'll take it that you know for certain that the programmer is at fault, and not another part of the controls such as a motorised valve or thermostat for example.
     
    Last edited: 30 Nov 2021
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  4. JimDr

    JimDr

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    Thanks for reply..yes its def the programmer I have replaced the valves multiple times over the last 20 years..the programmer is dead, although if I take it off and put back on I can usually get it to work.manually. what programmer could I use that would fit directly on to that back plate...thanks
     
  5. stem

    stem

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    Most of them except the FP720. :rolleyes:

    Honeywell, Drayton, Horstmann, even Hive it you wanted to go 'smart'.

    The Drayton LP722 would be a similar unit to the Danfoss that you have, it uses the industry standard backplate and has the same connections.

    Capture.JPG

    If you find a programmer you like the look of and post back on here someone will be able to confirm.
     
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  7. JimDr

    JimDr

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    Thanks again will have a look at the alternatives
     
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