Ecodan standby power consumption

[ProDave]

2 hours ago, JohnMo said:

As I said loads of entries ago, the heater is stop liquid refrigerant forming in the lube oil.  If you could or did disable the heater, you would be buying a new compressor quite quickly.

 

The only way to stop this load is to switch the unit off at the mains.  When the unit restarts it will go through a heat up period to ensure the refrigerant is expelled from the lube oil before starting the compressor.

I read the tone of this thread as more of a "which ASHP to avoid buying"  or at very least a question to ask of your supplier and demand a reply in writing stating what the standby power consumption is, so if you then encounter such a high standby power consumption you have a valid complaint.

 

I do agree, if you have one of these power gobblers, turn it off in the summer.

[JohnMo]

This arrival tells you all about the heater etc.

https://buildequinox.com/news/?id=4711

 

[MikeSharp01]

24 minutes ago, JohnMo said:

This arrival tells you all about the heater etc.

https://buildequinox.com/news/?id=4711

Scroll compressors only need apply by the looks of it - I think we kind of knew it but confirmation is valuable.

[joth]

40 minutes ago, MikeSharp01 said:

Scroll compressors only need apply by the looks of it - I think we kind of knew it but confirmation is valuable.

 

Fair enough except to main heatpump in contention, the ecodan, has a hermetic scroll compressor, but still needs the very power hungry preheater. (And so helpfully described as not having a crankcase compressor, but using the "resistive method" instead, by the datasheet posted a few pages back).

 

So I think @ProDave's advice to ask for a guaranteed standby power draw is the best bet, rather than try and guess based on the design. 

[Luke1]

16 hours ago, JohnMo said:

As I said loads of entries ago, the heater is stop liquid refrigerant forming in the lube oil.  If you could or did disable the heater, you would be buying a new compressor quite quickly.

 

The only way to stop this load is to switch the unit off at the mains.  When the unit restarts it will go through a heat up period to ensure the refrigerant is expelled from the lube oil before starting the compressor.

 

If you are using 5kWh a day on standby, while waiting to heat DHW, you may as just switch it off and use your immersion.

I had picked up on this a while back. Hence why I took an extract from the Nibe installer handbook. 

 

Given the fact that the book states a number of different standby states would suggest that the crankcase heater mode should not be the default standby mode that I have so far witnessed.

 

I am unable to find out what preset temperatures and sensors are required for the system to enter standby mode, however you would have thought in these current warm conditions that the crankcase heater would possibly turn off? If it doesn't then perhaps Nibe providing standby consumption rates for modes other than crankcase heater mode is very misleading.

 

The Nibe uses 0.72kWh per day in standby 'crankcase heater' mode, so whilst not as bad as other systems noted here, its still adds up to a significant sum over the course of a year based on current energy prices. (More than £60!)

[SteamyTea]

7 minutes ago, Luke1 said:

Nibe uses 0.72kWh per day

Around half my current DHW needs. There is an advantage of having a proper gravity fed system with a tank in the loft, rather than draw in cold water from the ground all the time.

 

[markharro]

I have read this whole thread now - has no-one spoken to Mitsubishi direct to get a firm answer on this standby power from them? I may try now as I am interested in one of their ASHPs.

On a separate point, we are getting 3phase into the new house - does this give any issues to be aware of with an ASHP? thanks

[Benpointer]

5 hours ago, markharro said:

I have read this whole thread now - has no-one spoken to Mitsubishi direct to get a firm answer on this standby power from them? I may try now as I am interested in one of their ASHPs...

Er... isn't that what PhilT did, and posted their answer on 6 June?

Edited June 17, 2022 by Benpointer

[SteamyTea]

If anyone has an unit, at my end if Cornwall, I can come and put a logger in it sometime.

[HarryUp]

I am a little late to the thread as I only ended up here after trying to find some explanations for the apparent performance of my own system, and the answers are already here, even if they are a little dispiriting. We have only had our Ecodan PUZ-WM85VAA running for a little over three months so only have limited experience of its performance, and data gleaned from the reporting of the FTC6 controller. (I intend to install some OpenEnergyMonitor monitoring but they are short of supplies at the moment.) I was initially puzzled by the May decline in COP for space heating to the point where it was less efficient than DHW, but the summer setting from the start of June that turns all heating periods off has made the nature of the problem stark – so clear it is a surprise that seems to be little known (perhaps it is specific to the newer models?).

To add my small amount of data to the small pool here: in the 21 days since the start of June the HP has drawn 26kWh to deliver 76kWh of heat for DHW, and 38kWh to deliver 0kWh of space heating – which given the amount time it has spent on DHW is pretty low means that it is consuming 1.8kWh per day in standby mode. This doesn't seem to match with the figures that were in the Mitsubishi doc – and presumably would be higher when the weather is colder but the heating is not required.

The only relief is that as we have a PV system I suppose a lot of this draw will be met from that rather than grid import. I had delayed considering a PV diverter to see how it would work out over the summer first, but elimating c200+ kWh of unproductive usage by switching the unit off is definitely a reason to consider one.

[JamesPa]

The Ecodan technical document posted earlier actually quotes the standby power for the "PUHZ-W85VHA".  If the figures are to be believed the energy consumption would be 0.84kWh/day (35W*24h=0.84kWh or 28W*24=0.672kWh per day, depending on ambient.

 

Now we don't know how similar your model, the PUZ-WM85VAA, is (does anyone know the taxonomy of Mitsubishi model numbering?).  Furthermore, at least in some cases, they seem to use the same model number for R410 and R32 versions, just tagging the refrigerant on the end and they also have version numbers.  This being the case we don't actually know exactly which model their technical document refers to.  Since a change of refrigerant implies a change of compressor, and the standby consumption is largely due to the compressor, there is no reason at all to expect the R32 and R410 versions to have the same consumption.

 

I emailed Mitsubishi yesterday about the PUZ-WM112VAA R32 (quoting the technical document), I am awaiting a reply.

 

At the present time I don't think we have enough information to infer the consumption of any model that has not been specifically measured.  It seems, for now, very much a case of Mitsubishi caveat emptor (with apologies to any Latin scholars if Latin word order differs).  Having said that its also clear that the problem isn't unique to Mitsubishi though, albeit that there appears to be evidence that LG, at least, is better.

 

I am now working on the assumption that turning off altogether and using a solar diverter is the summer solution (fortunately I already have the solar diverter), but I dont know the 'right' solution for the shoulder season!

 

 

[Stones]

On 06/06/2022 at 18:38, PhilT said:

According to the data sheet I attached above yours is only 54W when on and 15W when off, so average only 35W (or 28W >21degC). Which precise full model description is yours? The mystery is why LA322's 8.5 (a VAA?) and my 11.2 (PUZ-WM112VAA) consume a lot more. I can't get a clear answer from Mitsubishi tech help but I'm not going to worry too much as the overall annual performance of my unit is spectacularly good and way better than my expectations.

 

Mine is a PUHZ-W85VHA2-BS

 

As per comments above, in summer the heating registers energy input, but no output.  On the basis of those figures it seems to be using between 16W and 25W (380-600W per 24 hours), although how much of that is for the controller and how much for the heater I do not know.

[SteamyTea]

20 minutes ago, Stones said:

380-600W

Do you mean Wh.

[Stones]

Between 380W - 600W consumed every 24 hours.

[Temp]

Yeah so 25W continuous is 600WH or 0.6kWH per day. That's not as bad as some.

 

Equivalent to five LED downlight bulbs on continuously.

[SteamyTea]

3 hours ago, Temp said:

Equivalent to five LED downlight bulbs on continuously.

Mine are 3W ones, so 8 of them

[JamesPa]

Here is Mitsubishi's response to the question ' what is the standby consumption of a PUZ-WM112VAA R32.  Basically it says that the standby power is 15W.  I expect this excludes the controller which is sold separately or combined with the cylinder.

 

The reference to 'the document you sent' is the one posted earlier on this forum 'from Mitsubishi Tech Support'.  Not sure what to say about this.

 

Also, it looks from this page like the PUZ models are R32 and PUHZ are R410.  

 

https://library.mitsubishielectric.co.uk/pdf/directory/heating/technical_documents/current/service_manual/outdoor_unit

 

From Mitsubishi:

 

 

 

Hi James,

 

I have attached the product fiche which gives details on the power consumption in other modes than active. The snapshot from below gives the details.

 

 

The document you sent  is not an official Mitsubishi Electric document so we wouldn’t be able to comment on this.

 

Also, if you are interested to find the standby load for the cylinder units as well, this can be found in the Databook by clicking link here to relevant pages (Domestic Hot water tank row). The standby power input varies from cylinder to cylinder with the range being between 0.026-0.045kW.

 

Kind regards,   John

wm112xx_001_001_uk.pdf

[SteamyTea]

55 minutes ago, JamesPa said:

 

 

 

Seems to read as no power to the crankcase.

[JamesPa]

...or no crankcase heater mode.

[SteamyTea]

27 minutes ago, JamesPa said:

...or no crankcase heater mode.

Write back and ask what the power draw of it is.

[PhilT]

For the latest R32 models they don't yet know. Hopefully the calls they are getting as a result of this thread will motivate them to find out. My best guess after many weeks of monitoring is around 1kWh per day in summer (11.2kW single phase model). I'm OK with that - it's a star performer for the year as a whole

[joth]

13 hours ago, SteamyTea said:

Seems to read as no power to the crankcase.

This is consistent with the product specification sheet I posted way back that says crankcase heater is N/A watts. Also the informational document tech support that said words to the effect "as ecodan does not have a crankcase heater,  it uses the resistive method instead".

I presume this means leaving a small DC current running through the coils of the compressor motor, rather than through a dedicated heating element, but my guess is as good as yours. (it's a stupid statement, in what way would a crankcase heater, if it had one, not be using a resistive method ?)

 

[JamesPa]

I emailed Mitsubishi again about the standby consumption of the 11.2kW R32 model, as suggested by ST.  They are still claiming 15W (0.36kWh per day) in any standby mode for the PUZ WM115VAA (or VAA-BS).  See attached (the previous product fiche had an error on the rating sticker, which they corrected in response to my question). 

 

The PUZ WM115VAA (-BS) is the current R32 11.5kW single phase model ( (-BS) = with or without salt protection) and I think the figure certainly excludes the controller.  Does anyone have evidence that they are wrong and that this model consumes a lot greater than 15W.

 

Incidentally they confirm that PUHZ- is the R410 model, PUZ- the R32 model.  

wm112xx_001_001_uk.pdf

[PhilT]

2 hours ago, JamesPa said:

I emailed Mitsubishi again about the standby consumption of the 11.2kW R32 model, as suggested by ST.  They are still claiming 15W (0.36kWh per day) in any standby mode for the PUZ WM115VAA (or VAA-BS).  See attached (the previous product fiche had an error on the rating sticker, which they corrected in response to my question). 

 

The PUZ WM115VAA (-BS) is the current R32 11.5kW single phase model ( (-BS) = with or without salt protection) and I think the figure certainly excludes the controller.  Does anyone have evidence that they are wrong and that this model consumes a lot greater than 15W.

 

Incidentally they confirm that PUHZ- is the R410 model, PUZ- the R32 model.  

wm112xx_001_001_uk.pdf 351.04 kB · 3 downloads

I've called them so many times now. Each time I get a different answer, the latest being an admission that they don't have actual measured data on the latest R32 models. While away from home all of last week my house consumed 3.2kWh per day, of which all the mains plug appliances, measured by watt meter, totalled 2.2kWh per day, leaving 1kWh per day for the heat pump compressor AND controller. That is for a PUZ-WM112VAA which is the latest 11.2kW R32 model

[JamesPa]

8 hours ago, PhilT said:

I've called them so many times now. Each time I get a different answer, the latest being an admission that they don't have actual measured data on the latest R32 models. While away from home all of last week my house consumed 3.2kWh per day, of which all the mains plug appliances, measured by watt meter, totalled 2.2kWh per day, leaving 1kWh per day for the heat pump compressor AND controller. That is for a PUZ-WM112VAA which is the latest 11.2kW R32 model

Your measurements are very plausibly consistent with the data Mitsubishi gave me and which I posted above. 

 

1kWh/day is 40W.  Mitsubishi says its 15W for the outdoor unit, leaving 25W unaccounted for.  I cant find a spec for the controller, but Mitsubishi do state that the standby power of their cylinders (which include the controller) as 26-45W.  Apart from the controller, the cylinders are mostly plumbing, so you would expect the standby power to be mostly the controller plus perhaps one or two solenoid valves thrown in (or something similar).  Thus 25W for the controller seems a very likely (and anyway quite plausible) figure, albeit one that would probably make it feel quite warm to the touch.  The controller is never really on 'standby' I suspect, its sitting there 'doing its thing' all the time.

 

All in all I think your measurement plus the Mitsubishi product fiche convinces me that the PUZ-WM112VAA R32 is very likely ~15W, with the controller very likely ~25W.  These are, to my mind, both reasonable figures and nowhere near the 200W that started this thread.  There does seem to be evidence (from Mitsubishi and others) that some Mitsubishi models, particularly the PUHZ (R410) 3-phase models, have a significantly higher consumption.  if anyone has any further figures for specified models then it would be interesting to aggregate them and check out further the various data Mitsubishi have provided.