Ecodan standby power consumption

[JamesPa]

2 hours ago, Tom said:

Quote from Cool Energy: "The standby power consumption of all of our inverTech range is 0.013kW/h or 312w per 24hours as per our independent TUV test data."

 

2 hours ago, joth said:

Wow. The main thing this tells us is Cool Energy have absolutely no idea how Energy is measured.

A constant 13W load is 312Wh per day, so let's go out on a limb and assume that's what they meant?

 

2 hours ago, SteamyTea said:

They don't know what they are talking about.

OMG joth and ST are correct - CoolEnergy are in the energy business and they apparently don't know how to measure energy, and that's even before the Government thinks its sensible to have us go back to measuring energy in horsepower-hours (or whatever mad units you choose).  I wonder if our Government has realised that all our 'imperial' units are now in fact legally defined in terms of SI units anyway.  A yard is 0.9144 metres exactly, a pound is  0.45359237 kilos exactly and a second is... well a second.

 

Thankfully TUV are German and so can presumably be trusted to do engineering properly.  Neither 13W nor 312Wh appear in the excerpt from the TUV certificate so goodness knows what the figures Cool Energy quote are based on, but at least 38W + 9W is reasonably low as a (presumed) standby consumption.

 

 

To be clear on units, for those who aren't (and add to STs explanation):

 

- a watt (symbol W) is a unit of power = rate at which energy is consumed/produced - the amount of energy per unit of time.  Think of it as how hard you have to work.   A kilowatt (symbol kW) is 1000 watts

 

(The most used imperial units of power is the horsepower or the British thermal unit per hour.  To this day radiators are often quoted in Btu/h, goodness knows why.  The average horse, incidentally, has a maximum output power of about 15 horsepower but an average over a day of about one horsepower)

.

- a kilowatt hour (symbol kWh) is a unit of energy and is what you pay for for when you buy electricity or gas.  We also sometimes call this a 'unit'.  Think of it as how hard you have to work multiplied by how long you have to work that hard.  So if you use consume energy at the rate of 1kW for one hour, you will use 1kWh.  Similarly if you consume energy at the rate of 0.5kW for two hours, you will also use 1kWh.   

 

(The most used imperial units of energy are the British thermal unit or, oddly enough, the kWh - because we have measured electricity in kWh for decades.)

 

- A joule (symbol J) is also a unit of energy but its too small to be useful for most house-related purposes.  1 watt = 1 joule per second, so a kilowatt hour is 1000 joules per second for an hour, ie 3,600,000 joules.  

 

SI units are written with lowercase letters except when the unit is abbreviated and the unit is named after a person.  So watt (W), pascal (Pa), second (s), metre (m), joule (J), kilogram (kg), ampere (A) ohm (upper case omega), volt (V). etc.   Furthermore they all relate directly to each other in a logical and consistent fashion and are exactly the same worldwide.  Imperial units - lets not go there!

 

 

 

 

[JohnMo]

Hope you don't go lots of mph, and get a low mpg, while spending your decimal £.

[joth]

1 hour ago, PhilT said:

Isn't your heat pump massively over-capacity based on that peak usage - that's a jaw dropper - which model number is yours? Mine is a PUHZ-W112VAA. It's all very puzzling - the mission to understand goes on...

 

Yeah PHPP said peak load was 3kW, the MCS method said 5kW (because they're not allowed to believe our airtightness goal).

We oversized it to reduce UVC reheat time.

In retrospect that was probably a silly choice as it struggles to modulate down to deliver cooling in our FCU so I'm having to add a larger buffer tank.

 

It's a puz-wm85vaa

 

So is it a PUHZ Vs PUZ issue?

If I understand their numbering scheme, yours is R410A, mine is R32.

[SteamyTea]

7 minutes ago, JamesPa said:

and a second is... well a second.

One second is the time that elapses during 9,192,631,770 cycles of the radiation produced by the transition between two levels of the cesium 133 atom.

But only with no relativistic effects I assume.

 

[SteamyTea]

7 minutes ago, JohnMo said:

decimal £.

Those will be changed to Grote's.

Or a stable crypto coin.

[Simplysimon]

1 hour ago, SteamyTea said:

 

That Lsd we had in the early 70s, been replaced with Ritalin.

but which one is better/more fun/ more interesting?

[LA3222]

34 minutes ago, joth said:

 

Yeah PHPP said peak load was 3kW, the MCS method said 5kW (because they're not allowed to believe our airtightness goal).

We oversized it to reduce UVC reheat time.

In retrospect that was probably a silly choice as it struggles to modulate down to deliver cooling in our FCU so I'm having to add a larger buffer tank.

 

It's a puz-wm85vaa

 

So is it a PUHZ Vs PUZ issue?

If I understand their numbering scheme, yours is R410A, mine is R32.

I have the same model as you. I have the ridiculous standby losses going on.

[SteamyTea]

19 minutes ago, Simplysimon said:

but which one is better/more fun/ more interesting?

If Ritalin keeps small children quiet. Then Ritalin.

Shame I am not allowed to smoke a joint in a cafe, I would be pretty mellow about the child centred parents trying to stop the little shits ruining everybody's lunch hour.

 

(Disclaimer: I am against non legal and illegal usage of prescription drugs)

[Simplysimon]

7 minutes ago, SteamyTea said:

f Ritalin keeps small children quiet. Then Ritalin.

more interesting to see them drop a little Lsd

8 minutes ago, SteamyTea said:

Shame I am not allowed to smoke a joint in a cafe,

take in some home made cookies?

[SteamyTea]

3 minutes ago, Simplysimon said:

interesting to see them drop a little Lsd

What Steve Jobs said about Bill Gates.

[PhilT]

57 minutes ago, joth said:

 

Yeah PHPP said peak load was 3kW, the MCS method said 5kW (because they're not allowed to believe our airtightness goal).

We oversized it to reduce UVC reheat time.

In retrospect that was probably a silly choice as it struggles to modulate down to deliver cooling in our FCU so I'm having to add a larger buffer tank.

 

It's a puz-wm85vaa

 

So is it a PUHZ Vs PUZ issue?

If I understand their numbering scheme, yours is R410A, mine is R32.

Mine is R32. I just looked at the plate on the side and it says PUZ-WM112VAA. The original quote spec said PUHZ-W112VAA

[PhilT]

Just had an interesting conversation with Liam at Mitsubishi UK Technical. The compressor on the PUZ-WM85VAA and PUZ-WM112VAA models is a scroll compressor. It is definitely working correctly in having a heater keeping the compressor warm, using up to 6kWh per day if idle 24/7 but, depending on the time of year/% of time working, not drawing power all the time, and none at all if working 24/7. The quoted SCOP of 3.6 or whatever, takes this power draw into account, which my first year data suggests is very conservative as my heat pump usage of 3,300kWh on an estimated EPC space heating/hot water (MCS certified) heat loss of 16,000 kWh gives a SCOP of 4.8 which is phenomenal. It was a very warm winter and I did get some extra insulation put in so may be a bit top side. As both a tech and a fitter Liam suggests that if you can put up with the hassle you can switch it off every day as long as you switch it on at least 2 or preferably 3 hours to be safe, to warm up before use. However if you get this wrong it cannot be damaged as it will prevent itself from starting unless the compressor is up to temperature, you will just have to wait.

[SteamyTea]

12 minutes ago, PhilT said:

The compressor on the PUZ-WM85VAA and PUZ-WM112VAA models is a scroll compressor

That is odd as, with limited research, I was under the impression that scroll compressors did not have this problem, only the reciprocation ones.

But at least you got to chat to someone that seemed to know about it.

6 kWh/day is double my current daily usage.

[JamesPa]

24 minutes ago, PhilT said:

Just had an interesting conversation with Liam at Mitsubishi UK Technical. The compressor on the PUZ-WM85VAA and PUZ-WM112VAA models is a scroll compressor. It is definitely working correctly in having a heater keeping the compressor warm, using up to 6kWh per day if idle 24/7 but, depending on the time of year/% of time working, not drawing power all the time, and none at all if working 24/7. The quoted SCOP of 3.6 or whatever, takes this power draw into account, which my first year data suggests is very conservative as my heat pump usage of 3,300kWh on an estimated EPC space heating/hot water (MCS certified) heat loss of 16,000 kWh gives a SCOP of 4.8 which is phenomenal. It was a very warm winter and I did get some extra insulation put in so may be a bit top side. As both a tech and a fitter Liam suggests that if you can put up with the hassle you can switch it off every day as long as you switch it on at least 2 or preferably 3 hours to be safe, to warm up before use. However if you get this wrong it cannot be damaged as it will prevent itself from starting unless the compressor is up to temperature, you will just have to wait.

If all that is true, and it sounds like you spoke to someone knowledgeable so there is a good chance it is, then its very helpful and gives the possibility to mitigate the effect in many cases.  In the depths of winter its likely that the heating is running 24/7 anyway, so the 'standby' load is not relevant.  In summer and much of the shoulder season, if you have solar pv (like I do) then the ashp can be switched off completely and the solar PV takes over.  So that just leaves march-mid May and September/October as months when the standby power is a particular problem.  But its warmer then so the compressor should heat up from cold quicker!  Maybe a bit of thinking about times of use could resolve this?  

 

Im personally reluctant to rule out the Mitsubishi product yet, it seems to be generally well thought of, relatively attractive, not super heavy like the Vaillant, and has a different form factor to many others which, in some circumstances (including my own) matters!

[joth]

https://library.mitsubishielectric.co.uk/pdf/download_full/4116

 

This document section 3 says:

1. It's a hermetic scroll compressor.

2. The crank case heater has a rating of "--" watts. I assume that means N/A, i.e. no

 crank case heater installed??

 

There's also mention of a drain heater, but no waiting of how many watts that might draw.

 

So I'm still in disbelief at Liam's answer.

 

 

[joth]

30 minutes ago, joth said:

https://library.mitsubishielectric.co.uk/pdf/download_full/4116

 

This document section 3 says:

1. It's a hermetic scroll compressor.

2. The crank case heater has a rating of "--" watts. I assume that means N/A, i.e. no

 crank case heater installed??

 

There's also mention of a drain heater, but no waiting of how many watts that might draw.

 

So I'm still in disbelief at Liam's answer.

 

 

 

 

 If it contains a 250W heating element, then (a) it should be listed on the service manual, and (b) I can't understand why mine has never drawn more than 25W peak.

 

I mean, I'm happy I'm impacted but this is still very concerning. I'm frequently asked for recommendations and ecodan was high on the list, but the fact their own tech support says 6kWh / day standby is to be expected  strikes them off the list completely, regardless of what version or reality that's based on)

 

[PhilT]

2 hours ago, JamesPa said:

If all that is true, and it sounds like you spoke to someone knowledgeable so there is a good chance it is, then its very helpful and gives the possibility to mitigate the effect in many cases.  In the depths of winter its likely that the heating is running 24/7 anyway, so the 'standby' load is not relevant.  In summer and much of the shoulder season, if you have solar pv (like I do) then the ashp can be switched off completely and the solar PV takes over.  So that just leaves march-mid May and September/October as months when the standby power is a particular problem.  But its warmer then so the compressor should heat up from cold quicker!  Maybe a bit of thinking about times of use could resolve this?  

 

Im personally reluctant to rule out the Mitsubishi product yet, it seems to be generally well thought of, relatively attractive, not super heavy like the Vaillant, and has a different form factor to many others which, in some circumstances (including my own) matters!

Agreed. The SCOP is amazing in spite of the ridiculous idle power draw. I also considered the Vaillant Arotherm Plus which on paper looks really good but there was nowhere to put it around my house without contravening the fire prevention rule minimum distance from windows, doors and drain covers and, as you hinted, the Mitsu size and shape is so compact for the power.

[SteamyTea]

2 hours ago, PhilT said:

16,000 kWh gives a SCOP of 4.8 which is phenomenal

I suspect, as I think has been mentioned before, that the 16 MWh estimate is wrong.

At a SCoP of 3.6, your house is probably using 12 MWh a year.  25% less energy than the estimate.

[HughF]

49 minutes ago, PhilT said:

Agreed. The SCOP is amazing in spite of the ridiculous idle power draw. I also considered the Vaillant Arotherm Plus which on paper looks really good but there was nowhere to put it around my house without contravening the fire prevention rule minimum distance from windows, doors and drain covers and, as you hinted, the Mitsu size and shape is so compact for the power.

I know it's off-topic, but can you elaborate on this fire prevention rule for the Arotherm Plus? Is that due to the use of r290 (propane) in these units?

[PhilT]

1 hour ago, SteamyTea said:

I suspect, as I think has been mentioned before, that the 16 MWh estimate is wrong.

At a SCoP of 3.6, your house is probably using 12 MWh a year.  25% less energy than the estimate.

Yes that's possible although the installer surveyor's estimate was even higher at 18,000kWh p.a. which looked reasonable vs. my condensing gas boiler usage of 21,000kWh p.a. at around 85% efficiency

[PhilT]

31 minutes ago, HughF said:

I know it's off-topic, but can you elaborate on this fire prevention rule for the Arotherm Plus? Is that due to the use of r290 (propane) in these units?

Yes exactly. I had chapter and verse specs and quotes from 2 different installers for the two different models. I had almost made up my mind to go with the Vaillant when the installer drew my attention to the requirement - respect to him.

[SteamyTea]

20 minutes ago, PhilT said:

my condensing gas boiler usage of 21,000kWh p.a. at around 85% efficiency

Or not at 85% efficiency.  That is what it was capable of in ideal conditions, not one out in the wild.

[JohnMo]

They are only that efficient when running at really low temps, well below the condensing temp and running for a long time.

 

Short running periods and high return temps possibly much lower efficiency.

[PhilT]

17 minutes ago, JohnMo said:

They are only that efficient when running at really low temps, well below the condensing temp and running for a long time.

 

Short running periods and high return temps possibly much lower efficiency.

Good point. What would be a reasonable % efficiency to assume? A few years ago we had 2 large extra radiators installed with the same boiler so return temperatures should have dropped significantly. A brief look online suggests ideal efficiency of 95% translates to real world efficiency nearer 80%. My EPS/MCS estimate of 16MWh gives 76% so seems reasonable? Still a very impressive SCOP of 4.8 including that annoying idle power usage.

[JohnMo]

A condensing boiler starts to condense at I think a 56 degC return temp, the more it condenses the more efficient it gets.

 

Cut and paste from heat geek, it shows steady state efficiency, a stop start kills the efficiency.  76 more like 70% would be nearer.