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Heat Pump Calc

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  • 27-02-2014 11:49am
    #1
    hugo29
    Closed Accounts Posts: 3,267 ✭✭✭


    Hi all

    I have a 14kw Heat pump which over the last two months was in use for 579 hours , i calculated this to be approx 278 euro

    is this correct


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    #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,594 Mod ✭✭✭✭2011


    hugo29 wrote: »
    Hi all

    I have a 14kw Heat pump which over the last two months was in use for 579 hours , i calculated this to be approx 278 euro

    is this correct

    I think that you will find that 14kW is the output of the haet pump.
    The electrical input would be far less.

    Most domestic installations would not be able to supply a load that large.

    Basically a unit of electricity costs about €0.17
    1 unit = 1kW for 1 hour.


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    #3
    hugo29
    Closed Accounts Posts: 3,267 ✭✭✭hugo29


    2011 wrote: »
    I think that you will find that 14kW is the output of the haet pump.
    The electrical input would be far less.

    Most domestic installations would not be able to supply a load that large.

    Basically a unit of electricity costs about €0.17
    1 unit = 1kW for 1 hour.

    thanks for the reply
    yes the way i worked it out was

    579 x 4kw x 0.12 (which is the average between day and night charge) which came out at 277 euro, but i have got an esb bill for 750 euro so i am doing something seriously wrong or i have a problem

    how would i calculate the electrical output of the heat pump


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    #4
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,594 Mod ✭✭✭✭2011


    hugo29 wrote: »
    579 x 4kw x 0.12 (which is the average between day and night charge) which came out at 277 euro


    I would expect that you will find that even though the electrical load is 4kW the system does not consume 4kW during all of the “on time”.
    Just like a fridge, it will switch a compressor and pump on and off as required to maintain a temperature set point.

    If I owned this unit I would install a kWh meter on the cable supplying the heat pump (to measure the units).
    An Owl energy meter would do the trick, these units can even be programmed to take account of dual tariff (day/night) meters. This would give you a good indication.

    but i have got an esb bill for 750 euro so i am doing something seriously wrong or i have a problem


    Have you looked at the other large electrical loads that you have?
    Buy the Owl meter and move it around every couple of days to monitor different loads to build up a picture of what is driving your bill this high.

    how would i calculate the electrical output of the heat pump


    You don't have an electrical output from the heat pump.

    The heat pump has two energy inputs:
    1) Electrical power
    2) Heat energy (normally from water in the ground or sometimes air)

    The desired output from the heat pump is in the form of heat.

    The electrical power input can be measured in kW as can the heat output.
    The idea is that the heat output exceeds the electrical input giving the illusion that the heat pump has an efficiency >100%

    The simplest way to obtain the output is from the manufacture’s documentation, which is bound to be a little "optimistic".


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    #5
    hugo29
    Closed Accounts Posts: 3,267 ✭✭✭hugo29


    2011 wrote: »


    I would expect that you will find that even though the electrical load is 4kW the system does not consume 4kW during all of the “on time”.
    Just like a fridge, it will switch a compressor and pump on and off as required to maintain a temperature set point.

    If I owned this unit I would install a kWh meter on the cable supplying the heat pump (to measure the units).
    An Owl energy meter would do the trick, these units can even be programmed to take account of dual tariff (day/night) meters. This would give you a good indication.



    Have you looked at the other large electrical loads that you have?
    Buy the Owl meter and move it around every couple of days to monitor different loads to build up a picture of what is driving your bill this high.



    You don't have an electrical output from the heat pump.

    The heat pump has two energy inputs:
    1) Electrical power
    2) Heat energy (normally from water in the ground or sometimes air)

    The desired output from the heat pump is in the form of heat.

    The electrical power input can be measured in kW as can the heat output.
    The idea is that the heat output exceeds the electrical input giving the illusion that the heat pump has an efficiency >100%

    The simplest way to obtain the output is from the manufacture’s documentation, which is bound to be a little "optimistic".

    thats great thanks for all that, First port of call is the owl energy meter so, and check all appliances, i suppose the usual suspects of dryer, washing machine, oven/cooker, even heat recovery unit


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