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Heat pump & RCD Query!

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  • 10-09-2009 9:42pm
    #1
    billy_beckham
    Registered Users Posts: 423 ✭✭


    Does a heat pump need to be protected by an RCD, have one that is tripping when the pump tries to start..

    Thanks...:confused:


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    #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    No, because it is "fixed equipment".

    It would be good to know why it is causing the RCD to operate. It would be normal for a heat pump to have a small leakage current.

    Does it have a dedicated RCD, or does it share an RCD with other circuits?


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    #3
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    Heat pumps present a large electrical load to the installation (generally over 8 kW). They also draw a large start up current and this might be what is cause an RCBO (combined MCB and RCD unit) or MCB to trip.


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    #4
    billy_beckham
    Registered Users Posts: 423 ✭✭billy_beckham


    Does it have a dedicated RCD, or does it share an RCD with other circuits?

    It is on a shared 63amp 30ma RCD

    They also draw a large start up current and this might be what is cause an RCBO (combined MCB and RCD unit) or MCB to trip.

    The RCD used to trip occasionally but lately it has been more frequent, have narrowed it down to the pump.

    Thanks for the advice...


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    #5
    davelerave
    Closed Accounts Posts: 1,712 ✭✭✭davelerave


    some 'fixed equipment' should have rcd protection but not a heat pump.


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    #6
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    That is correct.


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    #7
    davelerave
    Closed Accounts Posts: 1,712 ✭✭✭davelerave


    and obviously if removing rcd protection from the heat pump ,you should do an IR test/loop impedance test to verify the wiring is actually ok


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    #8
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    A bit of a thread revival,

    Has this rule changed now for heat pumps on RCD's/ RCBO's?

    There would also be cables running outside to feed the unit.

    So would this also indicated that an RCD/RCBO would be required?


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    #9
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    WATER HEATING APPLIANCES


    555.3.1...........a circuit supplying a water heating appliance shall be protected by an rcd

    555.3.2..........a circuit supplying auxiliary equipment associated with water services and water systems (eg:pumps)shall be protected by an rcd


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    #10
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    mikehammer67 wrote: »
    WATER HEATING APPLIANCES


    555.3.1...........a circuit supplying a water heating appliance shall be protected by an rcd

    555.3.2..........a circuit supplying auxiliary equipment associated with water services and water systems (eg:pumps)shall be protected by an rcd

    Cheers Mike,

    Thats what I was looking for.

    From what I can see regarding the Type of RCD/RCBO its a B type that would need to prevent nuisance tripping due to inverters/ compressors in the heat pump.

    http://www.abb.ie/product/ap/seitp329/4bd0ec0528a84420c1256f5500557772.aspx


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    #11
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    Just did a bit more researching,

    For an RCD & RCBO its a Type A DC Sensitive that would be needed.


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    #12
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    edit: ya i think type A rcd probably if you're fitting one

    (make sure the control panel doesn't come with rcd incommer etc. anyhow and that you're not doubling up-i'm not that familiar)


    i think it's usually C type then for the trip curve


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    #13
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    mikehammer67 wrote: »
    edit: ya i think type A rcd probably

    make sure the control panel doesn't come with anything anyhow and that you're not doubling up-i'm not that familiar


    i think it's usually C type then for the trip curve

    The "Type A DC sensitive" RCD covers pulsating DC currents which is what you get from the DC components in the heat pump.

    Its not something that there seems to be a lot of info on.

    But ideally I just want to avoid tripping from a incorrectly rated RCD.


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    #14
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    handy free doc here
    http://www.etci.ie/docs/ET214.pdf


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    #15
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    mikehammer67 wrote: »
    handy free doc here
    http://www.etci.ie/docs/ET214.pdf

    I have that here,

    Comes in handy at times alright.


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    #16
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    froshtyv wrote: »
    The "Type A DC sensitive" RCD covers pulsating DC currents which is what you get from the DC components in the heat pump.
    Why would a heat pump have pulsating DC currents?

    Edit: I see you are dealing with a heat pump with an inverter.

    I don't think that the regulations were written with heat pumps in mind to be honest.


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    #17
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    oil boilers and heat pumps are they 'water heating appliances' then?

    presumably so require rcd



    domestic well pumps?

    they dont seem to require rcd then as they're not part of a 'water heating' system?



    maybe someone else has a better understanding of these rules on pumps?


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    #18
    froshtyv
    Registered Users Posts: 225 ✭✭froshtyv


    I know if you ask RECI or the similar they will just specify to put in an RCD for the unit.

    The rules can be a bit vague for heat pumps.


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    #19
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    mikehammer67 wrote: »
    oil boilers and heat pumps are they 'water heating appliances' then?


    I agree that by reading the regulations and taking them literally a heat pump should be protected by an RCD.

    My point is that I feel (and I stress this is just my opinion) that the intention was not to have heat pumps protected by an RCD when the regulations were written. I do not think that an RCD be beneficial and may cause much nuisance tripping, in particular if an invertor / VSD / soft starter was used. I think it would be far better to concentrate on equipotential bonding and earthing of all pipework as well as suitable motor protection via fuses or MCB and overloads.

    I installed a heat pump several years ago and did not protect it with an RCD (there was no requirement at the time). I from memory it only had a DOL starter, so it probably would have worked fine with an RCD in circuit.

    Yes a heat pump could be described as water heating appliance. But it is heating water by using a refrigerant gas with the aid of a compressor (much like a fridge in reverse). My feeling is that the regulation was intended for immersion elements that heat the water directly.

    I know that where I work we have a large (entire building) boiler (superheated steam, 12 BarG at about 160 DegC) and RCDs certainly are not used to protect any of the pumps or any equipment associated with the boiler.

    Just to emphasise, don’t break the regulations. I am just expressing an opinion!! mikehammer67 is correct, the regulations as they are written require RCD protection for heat pumps (from what I can see).

    Side note: Have a look at 531.2.5.1 on page 103. This deals with nuisance tripping of RCDs.





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    #20
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,593 Mod ✭✭✭✭2011


    froshtyv wrote: »
    I know if you ask RECI or the similar they will just specify to put in an RCD for the unit.

    The rules can be a bit vague for heat pumps.

    From my experience RECI apply thier own version of the rules as it suits them.


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    #21
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    i don't like to have domestic circulation pumps on mcb only

    the rule maybe wasn't drafted with heat pumps in mind though

    i wonder if there was any clarification or amendments on that


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    #22
    mikehammer67
    Closed Accounts Posts: 699 ✭✭✭mikehammer67


    2011 wrote: »
    My feeling is that the regulation was intended for immersion elements that heat the water directly.


    555.3.2..........a circuit supplying auxiliary equipment associated with water services and water systems (eg:pumps)shall be protected by an rcd


    it seems that it may refer to boilers and heat pumps as the additional rule refers to auxiliary equipment


    certainly oil boilers and circ. pumps i've been rcd'ing for years


    ground source pumps i worked on we never rcd'd them alright


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