ASHP Efficiency vs SCOP

[Bashers]

I've been looking through specs of ASHP pumps and I'm confused (&concerned) by the "Efficiency" line in this table for a Daikin EDLQ05CV3:

 

• Space heating (Average climate) 55°C Class A++
• Efficiency 125
• SCOP 3.20

 

Publicity would have you believe that for every watt power consumed by this unit would result in 3.2 watts of heat "SCOP 3.20"

That's what I've been believing and running calculations with.

 

Now that figure above it, "Efficiency" suggest that for ever watt it consumes, it produces 1.25 watts of heat.

Granted that better than  gas boiler, but that's actually concerning.

That drastically changes my perception of what I'll get in terms of its performance, running costs and ROI.

[SteamyTea]

Wonder if they mean an efficiency of 125% at 55⁰ C output.

 

Most probably the 12 year old in the publicity department misunderstood what was given to them. 

[DanDee]

[SteamyTea]

5 minutes ago, DanDee said:

Not as simple as that if Denominator is a variable.

[DanDee]

https://tools.bregroup.com/heatpumpefficiency/background

[Jimmyjazz]

[Bashers]

Ok, so ive found the detail of this EU labelling here https://www.rehva.eu/rehva-journal/chapter/eu-commission-adopted-energy-labelling-criteria-for-space-heaters;

Quote

‘Seasonal space heating energy efficiency’ is in a key role as a base for labelling classification. It is defined as the ratio between the space heating demand for a designated heating season, supplied by a heater and the annual energy consumption required to meet this demand, expressed in %.

Even more unclear now.

 

From actual ASHP users, can you "hand on heart" say your heating Kwh usage has gone down by 66% for a SCOP of 3, or only 20% for an efficiency of 125%

[JohnMo]

2 hours ago, Bashers said:

• Space heating (Average climate) 55°C Class A++
• Efficiency 125
• SCOP 3.20

They are measuring different things.  SCoP is looking at the likely performance over the heating season, at all the different outside temperatures you are likely to get.

 

Space heating efficiency is at a set temperature of -10 deg C and as far as i can see takes the full system efficiency for a nominal system.

[DanDee]

https://heatpumpmonitor.org/

[DanDee]

https://www.waermepumpen-verbrauchsdatenbank.de/index.php?button=verbrauch

[Bashers]

Those are reassuring graphs, thanks

[ReedRichards]

1 hour ago, Bashers said:

From actual ASHP users, can you "hand on heart" say your heating Kwh usage has gone down by 66% for a SCOP of 3, or only 20% for an efficiency of 125%

 

I had an oil boiler before I had a heat pump.  But I don't know how efficient it was at converting oil to heat and the actual amount of heat required to keep my house at temperature will vary from one year to the next.  But making some estimates, I appear to achieve an SCOP of approximately 3, which is approximately what I was promised.  That's for heating and hot water.

[Kevm]

13 hours ago, Bashers said:

Ok, so ive found the detail of this EU labelling here https://www.rehva.eu/rehva-journal/chapter/eu-commission-adopted-energy-labelling-criteria-for-space-heaters;

Even more unclear now.

 

From actual ASHP users, can you "hand on heart" say your heating Kwh usage has gone down by 66% for a SCOP of 3, or only 20% for an efficiency of 125%

 

From your link (my bold)

 

"Efficiencies are determined based on respective CEN standards for boilers. All corrections F(i) relevant for boilers, e.g. due to auxiliary electricity consumption or due to standby loss, are negative. Different dedicated standards apply for determination of annual efficiencies of cogeneration devices and heat pumps. Additionally, for cogeneration devices one positive correction F(i) is applied due to electricity produced by the device itself. This makes it possible for a device to achieve efficiency exceeding 100%. A ‘conversion coefficient’ (CC=2.5) is used, reflecting the estimated 40% average EU generation efficiency referred to in Directive 2012/27/EU of the European Parliament and of the Council."

 

It looks like they are trying to shoehorn boilers and ASHPs into the same labelling requirements. I suspect the 125 number is 100*SCOP/2.5.  

 

My ASHP has a SCOP in the low-mid 3s.  I can measure COP quite accurately and the lowest daily average I have ever seen for heating (UK East Midlands) is about 2.75 and for HW 1.75.  That's for radiators at 40-45 degrees flow.

 

A

Edited February 27, 2023 by Kevm

[JohnMo]

10 minutes ago, Kevm said:

125 number is 100*SCOP/2.5

As I mentioned above the outside temperature used in all cases is -10 so ignore SCoP as it has nothing to do with it.  SCoP is a different measure all together.

[Kevm]

1 hour ago, JohnMo said:

As I mentioned above the outside temperature used in all cases is -10 so ignore SCoP as it has nothing to do with it.  SCoP is a different measure all together.

Where does the 125 come from then?

[JohnMo]

3 hours ago, Kevm said:

100*SCOP/2.5

CoP at -10 and 55?