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Heat Pump - What tarrif

  • 13-12-2021 12:26pm
    Registered Users Posts: 22 FTBr


    Moving into a new build house soon that has an air to water heat pump. Could anyone with this set up offer their thoughts on which electricity Tarriff to go with? Is a night rate or night boost rate worth going for?


  • Registered Users Posts: 13,913 ✭✭✭✭ Cuddlesworth

    In a new house, properly insulated, you set the heat pump to a set temp on the thermostat and walk away. Otherwise your just wasting money. So unless your charging a car overnight, running washer/dryers and doing other high electricity draw usage, I'm not sure what a night rate would do for you.

  • Administrators Posts: 50,614 Admin ✭✭✭✭✭ awec

    Yes, heat pumps are left on constantly, they're designed to keep the house at a constant temperature rather than heat up / cool down like traditional heating.

    They would not be as effective at heating a cold house as something like gas heating, so you don't let the house cool. Don't be turning it on and off.

  • Registered Users Posts: 22 FTBr

    Thanks, while I know they run constantly, I had assumed that the rate the house will lose heat increases at night time, and as a result the heat pump would run more often at night to maintain the constant temp.

    But I'm guessing from your responses this is not the case?

  • Registered Users Posts: 7,825 ✭✭✭ ongarite

    Depends on how the A2W system is heating your home.

    Is it UFH downstairs with radiators upstairs or radiators throughout?

  • Registered Users Posts: 26,452 ✭✭✭✭ Creamy Goodness

    I also have a heat pump and new* build, we lose about 0.5c during the night. modern thermostats have thresholds you can set so the heating won't kick on until it drops a 0.5-1.0c so it doesn't randomly switch on at night, but the difference between 1c is minimal and quite easy to heat back up.

    Your bills will generally be higher with a heat pump, but if you go induction for cooking you only have one bill (i.e. no Gas). To give you a rough estimate heating/lighting/electrics my 130sqm 4-bed house costs roughly €100 a month (on a 24hr tariff) and that's with two of us working from home since March 2020.

    *3 year old at this point.

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  • Registered Users Posts: 22 FTBr

  • Registered Users Posts: 288 ✭✭ staples7

    I found the bills were quiet high when we moved in first so changed to night rate. I have the heat pump timed to kick by adjusting minimum temperature lets say between 1AM and 5AM. I have it set like that for past 3/4 years and find it works well and heat pump only ever turns on for hot water during day time rate.

    Thats with a Mitsubishi eco dan unit. I do realise you are suppose to set it and let it! But find this works better and have a constant 20c

    There was a few months before we got time range and temp settings right but now a constant 20'c. Obviously if you hit a week of freezing weather you may need it to kick in longer.

    If you need more details just shout.

  • Registered Users Posts: 5,368 ✭✭✭ JimmyVik

    OP, I have a friend who records his usage religiously.

    He has an energy monitor on the heat pump so he knows exactly how much electricity is uses and when.

    I messaged him for the details and i'll post it for you.


    Heres what he sent

    1600sq ft house. B Rated. Heat pump always set to 21C daytime, 19C night time, sometimes turned up a degree when the relatives come to stay, never turned off. No other source of heating.

    KWh used per month in column on the right.

    Hope this helps.

  • Registered Users Posts: 22 FTBr

    Thanks a mil, from those figures it doesn't like the heat pump, even if under more load at night, uses enough to justify a night rate.

  • Registered Users Posts: 31 KLF

    Look for electric only deals. We got a big discount from Energia(41% off a kwh) for the first year on a 24hr tarrif for being "electric only".

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  • Registered Users Posts: 26,452 ✭✭✭✭ Creamy Goodness

    ooh, can you ask him what energy monitor he uses and where it's plugged into, this is the sort of stuff I'd love to have for mine.

  • Registered Users Posts: 5,368 ✭✭✭ JimmyVik

    I'll ask him. I think you can get them handy enough though. I have loads of the plug type ones myself. They only cost about a tenner each.

  • Registered Users Posts: 26,452 ✭✭✭✭ Creamy Goodness

    Thanks, being brutally honest here, I've no idea where any of my heating system is plugged into. All I know is it works and I get someone to service it once a year. Am Clueless :D

  • Registered Users Posts: 5,368 ✭✭✭ JimmyVik

    He told me the make of it was Gosuna. ITs an inline energy monitor that an electrician sourced and fitted for him. He connects to it via an app on his phone.

    He couldnt go with a normal plug in energy monitor because of the load or something like that. He used to have one that you just clamped around the live wire to show how much electricity was being used at that moment, but you couldnt record it. You could only tell when you looked at the readout. He wanted one that would record it automatically and he could check it via an app instead. The previous one was called "OWL" and he said he thinks there are newer ones now that have the app and record the info at all times too.