Heat pump power usage while idle or not heating

Mr Q · 31-05-2019 11:12pm #1

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?

Condenser · 01-06-2019 8:59am

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.

ShanE90 · 01-06-2019 10:41pm

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

unkel · 01-06-2019 11:06pm

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

mickdw · 01-06-2019 11:14pm

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.

unkel · 01-06-2019 11:18pm

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

KCross · 02-06-2019 12:17am

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?

antoinolachtnai · 02-06-2019 12:22am

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

Mr Q · 02-06-2019 8:16am

antoinolachtnai wrote: »

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

macgabhs · 02-06-2019 10:20am

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

ShanE90 · 02-06-2019 12:40pm

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

antoinolachtnai · 02-06-2019 2:33pm

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

ShanE90 · 02-06-2019 2:45pm

antoinolachtnai wrote: »

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

KCross · 02-06-2019 8:53pm

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.

Calahonda52 · 03-06-2019 12:46pm

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

threeball · 05-06-2019 2:22pm

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

Mr Q · 05-06-2019 2:25pm

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

threeball · 05-06-2019 3:07pm

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.

Mr Q · 05-06-2019 3:22pm

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.

threeball · 05-06-2019 4:30pm

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.

Mr Q · 07-06-2019 1:05pm

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.

threeball · 07-06-2019 1:52pm

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.

TheBigGreen · 07-06-2019 2:38pm

Hi,

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

Does anyone know the power usage when idle?

n97 mini · 07-06-2019 3:00pm

TheBigGreen wrote: »

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?

ShanE90 · 07-06-2019 10:45pm

TheBigGreen wrote: »

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

Mr Q · 08-06-2019 6:46am

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

air · 08-06-2019 7:40am

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?

threeball · 08-06-2019 9:27am

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.

ShanE90 · 08-06-2019 9:41am

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

ShanE90 · 08-06-2019 12:31pm

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.

air · 08-06-2019 12:53pm

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

ShanE90 · 08-06-2019 1:44pm

air wrote: »

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

Ye a bit alright, I made big changes to make the system work efficiently, more insulation, re plumbed the heating, new manifold, pressurized heating circuit ect, sized up the rads for the HP, new fuse board, dug up the driveway to get the outdoor unit on the garage...a lot of work I didn’t think the standby power would be the stumbling block...anyhow happy otherwise hopefully the other improvements will pay off come winter

air · 08-06-2019 6:08pm

Well at least you're getting good performance from it. It might be worth enquiring with the manufacturer if there's any improvement to be had via a firmware upgrade or similar. It seems strange to me that a sump heater would run 24/7/365 regardless of ambient temperature etc.

pj12332 · 30-01-2021 1:52am

Hi Just moved into a house with ecodan heat pump. Is a night meter better for these units? Any information appreciated.

Calahonda52 · 30-01-2021 9:01am

pj12332 wrote: »

Hi Just moved into a house with ecodan heat pump. Is a night meter better for these units? Any information appreciated.

I presume its UFH and not rads.

Some folk here reject the idea of the NRM because of the extra fixed costs and the higher day rate.
The math is something along the line that if you use over 1/3 of total at night, it breaks even and anything over that is a bonus.
It depends on you heat pump heating profile really.
Whats not done usually herein Ireland is install a buffer tank for the UFH which can be heated at night and used during the day.

eire1 · 30-01-2021 9:16am

All A2W Heat Pumps have a sterilisation settings in their engineering menus. They have to run for 30-60 minutes once a week to prevent Legionella. It has to hold 65deg for a period of time.

pj12332 · 31-01-2021 12:07pm

We have two zones, under ground heating downstairs and rads upstairs. Have started to monitor it now after we got a 300 euro bill for two months.

We turned our themostats down to 18 degrees in both zones as when at 20 the unit is constantly topping up the heat. Wanted to see if 18 was comfortable to live with as temperature in the house rarely drops below 18.5

The first night I started monitoring the night usage the system only used 4kwh. The second night I wake up and 10kwh has been used. Nothing changed on our end. So unless the water heating came on during the night or something I'm confused as to how it went from 4 to 10. Will monitor for a week to see.

In 36 hours we have now used 24kwh. Before last night we had only used 14kwh in 24 hours.

Would drive you mad this would.

KCross · 31-01-2021 12:59pm

pj12332 wrote: »

We have two zones, under ground heating downstairs and rads upstairs. Have started to monitor it now after we got a 300 euro bill for two months.

Are the bills estimated or did you submit readings to your provider?

Does your heat pump tell you how many kWh it is using each day?

In any case there have been some really cold -4C spells over the last month so you would have used a lot more during that.

Don’t sweat the one or two higher bills. Look at the yearly picture. That’s what counts.

alan partridge aha · 31-01-2021 2:09pm

Looking through this thread some units run 7w and others run 275w on standby. The moral of the story must be to check what each use on standby before purchase.

I'd be pig sick if I'd bought an expense heat pump thats going to cost me €100s in energy bills when not in use. Makes no sense.

Whats the life expectancy of these heat pumps?

nikola.m · 19-11-2023 9:58pm

Hello, I just install midea heat pump 16kwh (mhc-v16w/d2rn8-b) and just noticed that it is drawing 50w in standby all the time. The electricity consumption in the app and in the control unit is reporting only the electricity spend for active heating.

Does anyone have contacted the manufacturer about this issue or have found an alternative way to fix it?

Nelbert · 21-11-2023 8:07am

Ecodan user here. Shocked to see a figure of 200+w

I've a Shelly EM on both my indoor and outdoor portion circuit.

Outdoor draws 0w when no call for heat or water.

Indoor draws 20w or so but that circuit also includes the 8 heatmiser thermostats. So very little draw to keep the internal unit and it's controllers powered along with the thermostats around the house.

To be using 200w something is configured (or wired) wrong I'd have thought. A pump wired on instead of switched would be my thinking.

graememk · 21-11-2023 9:06am

https://www.boards.ie/discussion/comment/121394513#Comment_121394513

My 5m head circulation pump only uses 30w, so even 200 for a pump is high.

I wonder how it's been measured?

phil_space · 21-11-2023 10:59am

Viessmann user here. My 10 kWh unit uses 20w per hour when on standby, so c. 500w per day / 180 kWh per year.

Heat pump power usage while idle or not heating

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