Ecodan standby power consumption

[joth]

  On 25/04/2022 at 06:37, LA3222 said:

Well, as an update - I had emailed Mitsubishi technical about the issue and just recieved a response (fairly quick tbf). 

 

The ASHP requires constant electrical heat to the compressor, so it does not run cold after being idle for a while.

 

This is what the additional power is – and is totally normal.

 

So, it is apparently normal. Jeez, £500 a year energy consumption for an idle white box. I have followed up with 'how long before a call for heat kicks in does the compressor need to start warming up' - might get the thing on a timer of some description to cut down in this idling.

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I'd be interested in the model number, as our monobloc puz-wm85vaa doesn't have this phantom draw.

 

Looking at the databook it appears the ecodan monoblocs have  "hermetic twin rotary" compressors whereas the split units "hermetic scroll" compressors which sounds like it would make a difference.

 

The explanation from mitsubishi tech support is shocking though. 

[SteamyTea]

  On 25/04/2022 at 07:05, MikeSharp01 said:

Interesting read...

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May have a trip down to the ASHP training centre and see what they know about it.

Certainly makes choosing a manufacturer a bit easier, strike Mitsubishi off the list.

[ReedRichards]

Or strike Mitsubishi split units off the list if it turns out only that type has this issue.

[MikeSharp01]

Also interestingly I was looking at the parasitic loads that we may have in our build and was wondering just how much energy the home automation system was going to burn.

[Happy Valley]

We are soon to install an 8.5Kw Ecodan - is this one of the "affected" units?

[joth]

  On 25/04/2022 at 07:24, Happy Valley said:

We are soon to install an 8.5Kw Ecodan - is this one of the "affected" units?

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Which version?

our monobloc puz-wm85vaa doesn't seem affected. 

[ProDave]

  On 25/04/2022 at 06:54, MikeSharp01 said:

The LG units recently highlighted here have scroll compressors by the looks of it.

 

 

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Yes indeed they do.  When mine sits idle, it uses almost no power.  I meter the energy used by the ASHP using an old dual rate electricity meter, one rate for DHW and one rate for heating.

 

Actually the way the metering is switched that is one reading on the meter meters DHW use and the other reading on the meter meters "all other" use, i.e. whenever it is not heating DHW.

 

Now at this time of year, with the heating off, it seems to be clocking up just under 1kWh per week. which calculates at 6W background load.  I will settle for that.

[SteamyTea]

To my mind, reducing parasitic loads is vital for reducing energy usage.  Why I worked so hard on doing it.

[DamonHD]

  On 25/04/2022 at 07:47, ProDave said:

Now at this time of year, with the heating off, it seems to be clocking up just under 1kWh per week. which calculates at 6W background load.  I will settle for that.

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The meter may itself be using something getting on for that 6W...

 

Rgds

 

Damon

[SteamyTea]

  On 25/04/2022 at 07:59, DamonHD said:

The meter may itself be using something getting on for that 6W

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Am I right in thinking that normal electrical meters don't log anything below 0.5 Wh.

[ProDave]

This background / compressor heating load is certainly something I was not aware of and a question you should all now ask of the manufacturer before deciding which ASHP to use.  A 200W background load in your house would be bad enough, one in a box out in the garden is worse.

[ProDave]

  On 25/04/2022 at 08:02, SteamyTea said:

Am I right in thinking that normal electrical meters don't log anything below 0.5 Wh.

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Electronic meters only count up the useage I thought at each 1Wh that passes.  That is the trick that allows pulsed immersion heater PV dump units to work.  By turning a 3kW heater on for short bursts, and then off again, the same small bit of energy is being exported then imported and if the total flowing either way exceeds the threshold it will then be counted, but keep the "energy bucket" flowing back and forth small enough and it never gets metered.

 

But a continuous load, however small would just count up until it reaches the threshold to click the metered count up by 1. However long that takes.

 

My ASHP meter is an old spinning disk meter.

[dpmiller]

I can confirm standby on our  CoolEnergy unit is about the same as Daves'. Neither sump nor base heaters are actuated in standby.

[SteamyTea]

  On 25/04/2022 at 08:07, dpmiller said:

I can confirm standby on our  CoolEnergy unit is about the same as Daves'. Neither sump nor base heaters are actuated in standby.

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We need to make a list of ones that do, and ones that don't.

[SteamyTea]

  On 25/04/2022 at 08:05, ProDave said:

Electronic meters only count up the useage I thought at each 1Wh that passes. 

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Yes, that was it, the old 'cheating bucket'.  Never really understood it.

[LA3222]

  On 25/04/2022 at 07:35, joth said:

Which version?

our monobloc puz-wm85vaa doesn't seem affected. 

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It does. That is the model I have.

[LA3222]

  On 25/04/2022 at 08:02, ProDave said:

This background / compressor heating load is certainly something I was not aware of and a question you should all now ask of the manufacturer before deciding which ASHP to use.  A 200W background load in your house would be bad enough, one in a box out in the garden is worse.

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Absolutely. The reason I went Ecodan is it was considered on here to be one of the good ones.

 

Not happy with this vampire load. When I have the full complement of solar up I will probably care less, I certainly would have looked elsewhere had I known.

 

 

[LA3222]

As an aside, I have the emporia vue monitor on the go. Not sure how accurate the readings are that I'm getting, I've pulled the data and will look at Total consumption from that vs the meter in the cabinet to see broadly speaking how accurate it looks.

 

Regardless though, the manufacturer seems to think this vampire load is standard and acceptable.

 

Whenever the system is not running, the compressor will be receiving this said power to heat it.

 This is not something that can be placed on timer.

Edited April 25, 2022 by LA3222

[ReedRichards]

  On 25/04/2022 at 07:47, ProDave said:

Yes indeed they do.  When mine sits idle, it uses almost no power.  I meter the energy used by the ASHP using an old dual rate electricity meter, one rate for DHW and one rate for heating.

 

Actually the way the metering is switched that is one reading on the meter meters DHW use and the other reading on the meter meters "all other" use, i.e. whenever it is not heating DHW.

 

Now at this time of year, with the heating off, it seems to be clocking up just under 1kWh per week. which calculates at 6W background load.  I will settle for that.

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My LG Therma V monobloc was installed with its own electricity meter.  When the heat pump is idle the LED light on the meter is solid on, which I understand indicates zero (or negligible) power usage. 

[Dave C]

  On 25/04/2022 at 10:00, LA3222 said:

It does. That is the model I have.

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Very odd - you wonder if you've just got somebody particularly clueless in tech support, because if somebody else with the same model isn't suffering the same power draw issue, it rather suggests there is some setting for controlling it...

 

FWIW, I have the puz-wm50vaa and it's not doing anything of the sort - power draw when the pump is off is negligable (whole house is drawing ~60W during the nighttime when everything is idle, and that includes internet router etc. - and is roughly comparable to what I saw before the heat pump was installed, so I'm reasonably sure the heat pump is drawing <10W when it's idle).

[Happy Valley]

  On 25/04/2022 at 07:35, joth said:

Which version?

our monobloc puz-wm85vaa doesn't seem affected. 

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It's just arrived today and looking at the box it is the same as yours.

Edited April 25, 2022 by Happy Valley

[SteamyTea]

I have emailed someone who looks into all this sort of vampire loads and energy usage.

Shall see what he can find out as he has a bit more industry clout than me.

[m0deller]

I use emon for monitoring the ASHP. It's a great product. Our Aerotherm+ uses 8W on standby. 200W is crazy. 

[joth]

  On 25/04/2022 at 10:00, LA3222 said:

It does. That is the model I have.

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Fascinating.

Do you have freeze-stat disabled?

What is the outdoor temperature when it's drawing it?

 

I will put a dedicated CT on mine just to confirm...

[JamesPa]

This is well scary for a 'green' technology. 

 

There is another discussion of standby power consumption here https://heatpumps.co.uk/2013/08/13/stand-by-power-and-air-source-heat-pumps/  Various people have contributed some figures, but some of the posts confuse power and energy so I am not sure how reliable they are.  

 

And another here https://forums.moneysavingexpert.com/discussion/6298830/dimplex-ashp-running-cost with figures for Daikin, LG and Dimplex all of which seem to have quite high standby consumption if this post is to be believed.  

Edited April 25, 2022 by JamesPa