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Heat pump power usage while idle or not heating

  • 31-05-2019 11:12pm
    #1
    Registered Users Posts: 414 ✭✭ Mr Q


    I have an 8kw A2W NIBE F2040 installed and have been measuring the power usage to try and see what the base load of the house was.

    When the HP is not heating the house or the hot water it is using 70 watts, every hour of every day. This might not sound like a lot but would be over 600 units of electricity a year without heating anything. The circulation pump is about 25 watts of this usage.

    If i turn off the power on the internal unit, VVM 320, using the power switch on the front it is still using 40 watts. This is with no circulating pump, screen or anything else that i know of running.

    I am measuring this with a meter in the distribution board so don't think there is any issue with the accuracy of this.

    Does anyone else have similar experience with their heat pump of any brand?


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Comments

  • Registered Users Posts: 536 Condenser


    Most probably the sump heater. Most air to water units would consume similar as generally the compressor is outside. The oil in the compressor sump must be kept warm so it's at the right viscosity to flow and protect the compressor when it starts up. It's basically a heater wire wrapped round the compressor base.


  • Registered Users Posts: 237 ✭✭ ShanE90


    My 11kW Ecodan uses 275watts when on standby, no pumps no valves no compressor running... once you flick the isolator the power is drawn immediately even before the cylinder unit loads up and it’s not the crankcase heater the power is used by the inverter pcb and other electronics in the outdoor unit so there charged up and ready to start


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,854 CMod ✭✭✭✭ unkel


    ShanE90 wrote: »
    My 11kW Ecodan uses 275watts when on standby

    That's brutal.

    That uses 2,400kWh per year just in standby. The average Irish household uses 3,500kWh per year in total for all their appliances

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



  • Registered Users Posts: 21,783 ✭✭✭✭ mickdw


    Thats about 450 quid per year before it produces any heat. Madness. I really have doubts about these units.
    Too many reports of 350 per month esb bills around here from heat pump dwellings.


  • Moderators, Category Moderators, Motoring & Transport Moderators, Regional East Moderators Posts: 58,854 CMod ✭✭✭✭ unkel


    mickdw wrote: »
    Thats about 450 quid per year before it produces any heat. Madness. I really have doubts about these units.
    Too many reports of 350 per month esb bills around here from heat pump dwellings.

    If you have a heat pump, you also have a night rate meter (dual meter). Unless you're an imbecile

    On the dual meter, 275W 24/7 would be about €340 per year based on 18c day rate and 8c night rate

    Agree with your sentiments though

    "Wind is Ireland's oil" - An Taoiseach, 25/05/2022



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  • Registered Users Posts: 11,197 ✭✭✭✭ KCross


    ShanE90 wrote: »
    My 11kW Ecodan uses 275watts when on standby, no pumps no valves no compressor running.

    That cant be right? How sure are you of that?


  • Registered Users Posts: 9,072 ✭✭✭ antoinolachtnai


    What happens if you just switch it off when not needed?


  • Registered Users Posts: 414 ✭✭ Mr Q


    What happens if you just switch it off when not needed?

    I don't know about others but you cant turn mine off. You would have no hot water


  • Registered Users Posts: 275 ✭✭ macgabhs


    That Ecodan standby usage is mad. My house base usage is 300w that’s for a 16kw daikin air to water heat pump on but not heating, mhrv running, septic tank pumps and appliances on standby.

    On the OP query I do note my heat pump has an internal pump that kicks in regularly even when there is no heating demand. I tend to turn off the heating side of things around April to October mainly to avoid a few stats calling for heat at night or late evening when temps drop back a bit but also helps stop the intermittent pump use


  • Registered Users Posts: 237 ✭✭ ShanE90


    Yep pics attached the owl slightly out when compared to the fluke, It equates to around €1.10 per day for being powered up... given my house was built in the 70s I’m happy with the system as it’s a drastic improvement over my old oil boiler and lack of hot water setup


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  • Registered Users Posts: 9,072 ✭✭✭ antoinolachtnai


    Could you knock it off during the summer except for the few hours a day when it actually runs?


  • Registered Users Posts: 237 ✭✭ ShanE90


    Could you knock it off during the summer except for the few hours a day when it actually runs?

    You could I suppose but for us it’s probably not worth the hassle of not being able to shower/bath wash ect anytime with a young kid also some of the evenings are coolish and the heating comes on for an hour sometimes when the room temp drops


  • Registered Users Posts: 11,197 ✭✭✭✭ KCross


    ShanE90 wrote: »
    Yep pics attached the owl slightly out when compared to the fluke, It equates to around €1.10 per day for being powered up... given my house was built in the 70s I’m happy with the system as it’s a drastic improvement over my old oil boiler and lack of hot water setup

    It must be running a circulating pump or something 24/7. It really shouldnt be consuming that amount for doing nothing other than being powered up.

    There is a setting in mine (Nibe, not Ecodan) to tell it to stop the pumps once the summer comes in. It still fires up for 30mins once a day to heat water.

    I'd talk to someone that knows your HP and see if you can fix that. If its normal, its bad form for Ecodan.


  • Registered Users Posts: 10,925 ✭✭✭✭ Calahonda52


    KCross wrote: »
    It must be running a circulating pump or something 24/7. It really shouldnt be consuming that amount for doing nothing other than being powered up.

    There is a setting in mine (Nibe, not Ecodan) to tell it to stop the pumps once the summer comes in. It still fires up for 30mins once a day to heat water.

    I'd talk to someone that knows your HP and see if you can fix that. If its normal, its bad form for Ecodan.

    I agree that this is not looking good.

    If correct it complete undermines the HP space

    perhaps post here:
    https://les.mitsubishielectric.co.uk/contact-us

    It got a write up here also
    https://passivehouseplus.ie/news/marketplace/ultra-quiet-ecodan-takes-heat-pumps-to-the-next-level#addcomments


  • Registered Users Posts: 7,259 ✭✭✭ threeball


    I wouldn't paint all heat pumps with the one brush. Mine uses 5w on standby. My sister's uses 8w. Both gshps


  • Registered Users Posts: 414 ✭✭ Mr Q


    threeball wrote: »
    I wouldn't paint all heat pumps with the one brush. Mine uses 5w on standby. My sister's uses 8w. Both gshps

    Those are very low figures. What brands are they? Do you have circulating pumps powered separately that are not included in those figures


  • Registered Users Posts: 7,259 ✭✭✭ threeball


    Mr Q wrote: »
    Those are very low figures. What brands are they? Do you have circulating pumps powered separately that are not included in those figures

    Mines an Ovum, hers is Waterkotte. Circulating pumps should only run for 3-4 mins every hour to sample floor temp so I wouldn't include them in standby. When they run in mine they draw less than 50w which for 4 mins is negligible. I can see it all on the screen including the current COP and SPF over the week. It averaged 6.5 to 7 over the winter.


  • Registered Users Posts: 414 ✭✭ Mr Q


    threeball wrote: »
    Mines an Ovum, hers is Waterkotte. Circulating pumps should only run for 3-4 mins every hour to sample floor temp so I wouldn't include them in standby. When they run in mine they draw less than 50w which for 4 mins is negligible. I can see it all on the screen including the current COP and SPF over the week. It averaged 6.5 to 7 over the winter.

    Mine is a NIBE and the circulating pump runs 24 hours a day. The interface on yours sounds like it gives some very useful information.


  • Registered Users Posts: 7,259 ✭✭✭ threeball


    Mr Q wrote: »
    Mine is a NIBE and the circulating pump runs 24 hours a day. The interface on yours sounds like it gives some very useful information.

    It shouldn't run 24hrs a day. Theres some setting wrong I'd imagine or else the controller isn't very well designed.

    Yes theres great info. Its PV ready so can recognise if excess power is leaving from a house to go back on to the grid then modulate to suit the power available. It can automatically increase the hot water set point when free power is available and increase the house temp by a settable temp on a cold day to maximise the PV usage. It effectively can act as a big battery. The software even separates out the COP on PV running from normal running. I don't have that set up yet as PV system is on the to do list but its all there when I want it.


  • Registered Users Posts: 414 ✭✭ Mr Q


    threeball wrote: »
    It shouldn't run 24hrs a day. Theres some setting wrong I'd imagine or else the controller isn't very well designed.

    Yes theres great info. Its PV ready so can recognise if excess power is leaving from a house to go back on to the grid then modulate to suit the power available. It can automatically increase the hot water set point when free power is available and increase the house temp by a settable temp on a cold day to maximise the PV usage. It effectively can act as a big battery. The software even separates out the COP on PV running from normal running. I don't have that set up yet as PV system is on the to do list but its all there when I want it.

    I had never heard of the brand until you mentioned it, they do look good. Very expensive?

    The PV integration option built in would be very useful.


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  • Registered Users Posts: 7,259 ✭✭✭ threeball


    Mr Q wrote: »
    I had never heard of the brand until you mentioned it, they do look good. Very expensive?

    The PV integration option built in would be very useful.

    Bit more expensive but considering what you get I think it's well worth it. 490l hot water cylinder, fresh hot water system, it has a desuperheater system which produces the hot water while producing heating so the COP for hot water is the same as it is for heating and if I were to buy 7 or 8kw battery storage it would set me back about €8k I'd say. This unit is the equivalent so if you take that into account I think it's well priced.
    Can passively cool the house too but I didn't take that option.


  • Registered Users Posts: 742 ✭✭✭ TheBigGreen


    Hi,

    I'm currently getting PUHZ-W112VAA Mits Ecodan HP installed in my new build.

    Does anyone know the power usage when idle?


  • Registered Users Posts: 8,287 ✭✭✭ n97 mini


    Hi,

    I'm currently getting PUHZ-W112VAA Mits Ecodan HP installed in my new build.

    Does anyone know the power usage when idle?

    What does the manual say?


  • Registered Users Posts: 237 ✭✭ ShanE90


    Hi,

    I'm currently getting PUHZ-W112VAA Mits Ecodan HP installed in my new build.

    Does anyone know the power usage when idle?

    That’s the newer ultra quiet monoblock released last year so it should be lower than its predecessor


  • Registered Users Posts: 414 ✭✭ Mr Q


    It would be good if the manufacturers would print all of the various power usage figures. Plenty of figures available while under heating load but hard to find any for idle or standby


  • Registered Users Posts: 2,820 ✭✭✭ air


    ShanE90 wrote: »
    Yep pics attached the owl slightly out when compared to the fluke, It equates to around €1.10 per day for being powered up... given my house was built in the 70s I’m happy with the system as it’s a drastic improvement over my old oil boiler and lack of hot water setup

    Try your fluke (the one you used for the voltage reading) in whole current measurement mode for a possibly more accurate current reading. Should be easy do just by bypassing the MCB with the probes and switching it off for a few seconds. I have an owl and wouldn't put any great faith in them for accuracy at that range. Presumably it was reading the whole house idle load there as well?


  • Registered Users Posts: 7,259 ✭✭✭ threeball


    ShanE90 wrote: »
    That’s the newer ultra quiet monoblock released last year so it should be lower than its predecessor

    I'm no expert but the unit in the picture is not a monoblock, it's a split. I spent enough time researching them when choosing a unit. Monoblocks don't have packaged indoor units.


  • Registered Users Posts: 237 ✭✭ ShanE90


    threeball wrote: »
    I'm no expert but the unit in the picture is not a monoblock, it's a split. I spent enough time researching them when choosing a unit. Monoblocks don't have packaged indoor units.

    Mitsubishi have both monoblocks and split type available in pacakaged cylinder units the W-112VAA is the newer ultra quiet unit only available in a monoblock at present

    Split type means refrigerant pipes connect between the outdoor unit and cylinder unit transferring the heat this way instead of water


  • Registered Users Posts: 237 ✭✭ ShanE90


    air wrote: »
    Try your fluke (the one you used for the voltage reading) in whole current measurement mode for a possibly more accurate current reading. Should be easy do just by bypassing the MCB with the probes and switching it off for a few seconds. I have an owl and wouldn't put any great faith in them for accuracy at that range. Presumably it was reading the whole house idle load there as well?

    Just reading the idle load of the HP on standby is 1.1A the house is another .4 of an Amp, checked through the Fluke and is the same as using the clamp. Owl is only slightly out by a few watts.


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  • Registered Users Posts: 2,820 ✭✭✭ air


    Well that's disappointing, can't say I'd be happy to live with that level of background consumption myself to be honest.


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