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Air To Water Heat Pump Running Costs

  • 08-03-2016 11:30am
    #1
    Registered Users Posts: 88 ✭✭ Rataan



    I’m just wondering if anybody on Boards with experience of air to water heat pumps can advise on whether my running costs are normal or not, as they seem excessive to me?

    I have recently moved in to a new house. It’s a new build, BER A3, and the heating is a Panasonic Aquarea 9kW air to water heat pump. There is no UFH, the heat comes from aluminium rads. The house is a 4 bed semi. I have been keeping my eye on the electricity meter each day to see how much power it takes to heat my house, and it would appear to me that I am using way too much. I read on the SEAI website that a 4 bed semi should cost in the region of 700 euro per year to heat with a A2W heat pump. I am using approx 30kWh per day! That is combined electricity and heating, but I know from all of my old electricity bills from my previous house that I used an average of 6kWh per day for non-heating purposes. My new house has all new appliances, with better energy ratings, so I should still be seeing approx. 6kWh (if not better) on the appliances, but the remaining 24kWh still seems somewhat high to me? Can anybody on Boards with experience of these heating systems advise if they think this energy consumption is excessive, or not?

    I have reported this to my builder, and the answer I got was that because the weather has been so cold in recent months, the heat pump requires more energy to do its job. I understand that, but I did not think it would require THAT much extra energy. He also suggested that the ESB meter is reading wrong or that some other appliance in my house is drawing off the power! I have one of those OWL electricity monitors on order to rule both of those possibilities out.

    Any advice/suggestions welcome.


Comments

  • Registered Users Posts: 536 Condenser


    Rataan wrote: »
    I’m just wondering if anybody on Boards with experience of air to water heat pumps can advise on whether my running costs are normal or not, as they seem excessive to me?

    I have recently moved in to a new house. It’s a new build, BER A3, and the heating is a Panasonic Aquarea 9kW air to water heat pump.There is no UFH, the heat comes from aluminium rads.The house is a 4 bed semi.I have been keeping my eye on the electricity meter each day to see how much power it takes to heat my house, and it would appear to me that I am using way too much.I read on the SEAI website that a 4 bed semi should cost in the region of 700 euro per year to heat with a A2W heat pump.I am using approx 30kWh per day!That is combined electricity and heating, but I know from all of my old electricity bills from my previous house that I used an average of 6kWh per day for non-heating purposes.My new house has all new appliances, with better energy ratings, so I should still be seeing approx. 6kWh (if not better) on the appliances, but the remaining 24kWh still seems somewhat high to me?Can anybody on Boards with experience of these heating systems advise if they think this energy consumption is excessive, or not?

    I have reported this to my builder, and the answer I got was that because the weather has been so cold in recent months, the heat pump requires more energy to do its job. I understand that, but I did not think it would require THAT much extra energy.He also suggested that the ESB meter is reading wrong or that some other appliance in my house is drawing off the power!I have one of those OWL electricity monitors on order to rule both of those possibilities out.

    Any advice/suggestions welcome.


    Air to water on aluminium rads was always going to be a disaster so blame whoever installed it for you. They are too opposing technologies. One wants high temps the other wants low temps and never the twain shall meet.
    If you read through these boards there are a couple of posters who have laid out exactly how heat pumps should be installed and in the main they have been drowned out by the din of other rubbish. If heat pumps are installed as they should be they are fantastic and if you try to substitute them for an oil boiler like most installers then they are a disaster.
    Your situation can only be improved by doing three things, swap your rads for fan assisted low temp rads, install a buffer cylinder (I'm certain you won't have one) and get someone who knows what they're doing to install and recommission everything. Alternatively install an oil boiler as the system you have isn't compatible with a heat pump. Air to water units are also significantly less efficient in colder weather so that's adding to your problem.


  • Registered Users Posts: 88 ✭✭ Rataan


    Condenser wrote: »
    Air to water on aluminium rads was always going to be a disaster so blame whoever installed it for you. They are too opposing technologies. One wants high temps the other wants low temps and never the twain shall meet.
    If you read through these boards there are a couple of posters who have laid out exactly how heat pumps should be installed and in the main they have been drowned out by the din of other rubbish. If heat pumps are installed as they should be they are fantastic and if you try to substitute them for an oil boiler like most installers then they are a disaster.
    Your situation can only be improved by doing three things, swap your rads for fan assisted low temp rads, install a buffer cylinder (I'm certain you won't have one) and get someone who knows what they're doing to install and recommission everything. Alternatively install an oil boiler as the system you have isn't compatible with a heat pump. Air to water units are also significantly less efficient in colder weather so that's adding to your problem.

    Thanks for the reply, Condenser. I probably didn’t go into enough detail in my original post. It’s not a one-off build that I have, where I employed somebody to commission this type of system. The whole housing estate, as well as the previous phases (approx. 100 houses) were built with the same heating systems as standard.

    My rads are low temperature, although not fan assisted. There is also a buffer tank.


  • Registered Users Posts: 536 Condenser


    Rataan wrote: »
    Thanks for the reply, Condenser. I probably didn’t go into enough detail in my original post.It’s not a one-off build that I have, where I employed somebody to commission this type of system.The whole housing estate, as well as the previous phases (approx. 100 houses) were built with the same heating systems as standard.

    My rads are low temperature, although not fan assisted. There is also a buffer tank.


    Aluminium rads will still require a higher temperature to generate heat than fan assisted rads or ufh will. Every degree increase drops COP by 3%. So 10C means 30%. An with air to water as the air temp drops so does COP so you're caught on both side. Low energy collection temps and high energy rejection leading to more work being done by the compressor, lower COP and higher running cost.


  • Registered Users Posts: 2,872 ✭✭✭ Borzoi


    Rataan wrote: »

    I’m just wondering if anybody on Boards with experience of air to water heat pumps can advise on whether my running costs are normal or not, as they seem excessive to me?

    I have recently moved in to a new house. It’s a new build, BER A3, and the heating is a Panasonic Aquarea 9kW air to water heat pump. There is no UFH, the heat comes from aluminium rads. The house is a 4 bed semi. I have been keeping my eye on the electricity meter each day to see how much power it takes to heat my house, and it would appear to me that I am using way too much. I read on the SEAI website that a 4 bed semi should cost in the region of 700 euro per year to heat with a A2W heat pump. I am using approx 30kWh per day! That is combined electricity and heating, but I know from all of my old electricity bills from my previous house that I used an average of 6kWh per day for non-heating purposes. My new house has all new appliances, with better energy ratings, so I should still be seeing approx. 6kWh (if not better) on the appliances, but the remaining 24kWh still seems somewhat high to me? Can anybody on Boards with experience of these heating systems advise if they think this energy consumption is excessive, or not?

    I have reported this to my builder, and the answer I got was that because the weather has been so cold in recent months, the heat pump requires more energy to do its job. I understand that, but I did not think it would require THAT much extra energy. He also suggested that the ESB meter is reading wrong or that some other appliance in my house is drawing off the power! I have one of those OWL electricity monitors on order to rule both of those possibilities out.

    Any advice/suggestions welcome.

    24kWhr at 18C per kWhr is €4.32 per day. If the SEAI says approx €700, that's 162 days of heating., at full whack worst conditions. In summary it doesn't sound like anything is wrong


  • Registered Users Posts: 88 ✭✭ Rataan


    Borzoi wrote: »
    24kWhr at 18C per kWhr is €4.32 per day. If the SEAI says approx €700, that's 162 days of heating., at full whack worst conditions. In summary it doesn't sound like anything is wrong

    Thanks Borzoi. But if we make the assumption that I’ll be heating my house for 8 months of the year, and you have calculated that 700 euro will cover me for 162 days, that still leaves another approx. 80 days of heating that are required. The weather should be getting warmer over the next few months, which should reduce the heating bills (as the heat pump will not have to work as hard), but we also had a very mild winter, imo. Maybe you are right. Maybe there is nothing wrong, but I still would think that my daily consumption figures should be lower. I’m hoping that somebody with a similar heating system in their home might weigh in and be able to advise whether or not these figures are normal?


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  • Registered Users Posts: 2,582 ✭✭✭ MicktheMan


    Rataan wrote: »
    if we make the assumption that I’ll be heating my house for 8 months of the year

    You shouldn't need to be heating an A3 rated house for 8 months of the year. More like 6 months with little heating needed in the shoulder months.

    Borzoi is probably right.


  • Registered Users Posts: 88 ✭✭ Rataan


    MicktheMan wrote: »
    You shouldn't need to be heating an A3 rated house for 8 months of the year. More like 6 months with little heating needed in the shoulder months.

    Borzoi is probably right.

    Thanks Mick, I hadn’t considered that. If that is the case, then that looks to be the explanation and maybe there is no issue after all. I guess I’ll have to wait until the warmer months and re-evaluate it then.


  • Registered Users Posts: 3,017 ✭✭✭ John.G


    Rataan wrote: »
    Thanks Mick, I hadn’t considered that. If that is the case, then that looks to be the explanation and maybe there is no issue after all. I guess I’ll have to wait until the warmer months and re-evaluate it then.

    Hi Rataan, I know this post is old but do you have any idea of your running costs for your Heat Pump for the past two winters?.


  • Closed Accounts Posts: 1,997 gally74


    Borzoi wrote: »
    24kWhr at 18C per kWhr is €4.32 per day. If the SEAI says approx €700, that's 162 days of heating., at full whack worst conditions. In summary it doesn't sound like anything is wrong

    Night rate of 7 cent with border gains,


  • Registered Users Posts: 3,017 ✭✭✭ John.G


    gally74 wrote: »
    Night rate of 7 cent with border gains,

    Thanks, I saw that (part 2016) and was interested in the full year costs, and also full year costs for 2017.


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  • Registered Users Posts: 88 ✭✭ Rataan


    John.G wrote: »
    Hi Rataan, I know this post is old but do you have any idea of your running costs for your Heat Pump for the past two winters?.

    December 2016 - 754 kWh

    January 2017 – 802 kWh

     

    December 2017 – 1056 kWh

    January 2018 – 901 kWh

     

    These numbers are for total electricity usage in my whole house as shown by the electricity meter.  I have to estimate how many units are being used solely by the heat pump.  In my previous house (which had gas heating) I was consistently using an average of 180 kWh per month on electricity (lighting, cooking, dishwasher, washing machine, etc.).  Therefore I think it would be fair to assume that to calculate the power used by the heat pump, you could subtract 180 kWh from the figures above.

    The winter of 2016/17 was a lot milder than the winter of 2017/18, which could explain why the numbers increased.  Also, we had a new baby in the house from November 2017, so the thermostats were all turned up and the washing machine & dryer have been running non-stop!



    Before our baby arrived, the total annual electricity usage for the two previous years was approximately 6300 kWh per year.  Again, you can subtract 180 kWh per month to get an estimation of the heat pump power usage.



    I hope this info is of some use to you.  Overall, I’m happy now with my heat pump.  The figures are big and scary in winter, but they then drop off very low from April to October.


  • Registered Users Posts: 3,017 ✭✭✭ John.G


    Rataan wrote: »
    December 2016 - 754 kWh

    January 2017 – 802 kWh

     

    December 2017 – 1056 kWh

    January 2018 – 901 kWh

     

    These numbers are for total electricity usage in my whole house as shown by the electricity meter.  I have to estimate how many units are being used solely by the heat pump.  In my previous house (which had gas heating) I was consistently using an average of 180 kWh per month on electricity (lighting, cooking, dishwasher, washing machine, etc.).  Therefore I think it would be fair to assume that to calculate the power used by the heat pump, you could subtract 180 kWh from the figures above.

    The winter of 2016/17 was a lot milder than the winter of 2017/18, which could explain why the numbers increased.  Also, we had a new baby in the house from November 2017, so the thermostats were all turned up and the washing machine & dryer have been running non-stop!



    Before our baby arrived, the total annual electricity usage for the two previous years was approximately 6300 kWh per year.  Again, you can subtract 180 kWh per month to get an estimation of the heat pump power usage.



    I hope this info is of some use to you.  Overall, I’m happy now with my heat pump.  The figures are big and scary in winter, but they then drop off very low from April to October.

    Thanks for that.
    From the above your yearly average HP energy used is ~ 4140 Kwh, (6300-(12*180). BER rating of A3 is >50 and <75 Kwh/M2/annum, say average of 62.5 Kwh/M2/annum.
    Don't know what size the house is but a 150 M2 house would require 9,375 Kwh, a 175 M2 house 10,938 Kwh and a 200 M2 house 12,500 Kwh. This, respectively gives seasonal COPs of 2.26, 2.64 & 3.04. I accept that this is a estimate but I think it shows that the Heat Pump is probably performing OK given that you have radiators and not UFH. Its a pity that all heat pumps don't log their thermal output, some do, then one could get a very accurate feel for the COP but at the end of the day its the running costs compared to other forms of heating that really matter.The seai have published some numbers on this, I will try and find the link now.

    Edit: Couldn't find the link I was looking for but this simple calculation might be some help in comparing different systems.
    Yearly Saving = House Kwh requirement x ((gas or oil cost per Kwh/Blr.Eff.)
    - (HP elec cost per Kwh/SCOP))


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