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Ecodan Negative COP

  • 29 November 2023
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Hello

I’m new to ASHP having only had the system fitted in June of this year and only started using it in September. I read previously that the Ecodan 13Kw system should run at around 300% efficiency i.e. consume 1 unit of electrical energy and deliver 3 units of heat energy.

The installer didn’t provide any advice on how to use the system on completion just said that its all set up to go. 

My problem is that in November for example the DHW has consumed 59kWh and delivered 93kWh of energy whilst the heating system consumed 410 kWh and delivered 303 kWh. By my reckoning this is a negative COP on the heating side.

The system is set to auto adapt with the weather compensation curve in the background. The system is set at 16C and scheduled to kick in during the period 05.00 to 10.00 and again at 17.00 to 20.00 just to provide heat whilst the log burners kick in. I’ve noticed that on occasions the electric heater icon is showing on the controller screen.

Is there something obvious that I’m missing? Any advice would be appreciated.

Andy

  

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Best answer by juliamc 30 November 2023, 11:32

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Tim_OVO
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Hi @afrost4747 

 

You’re not alone with these questions and you’ve come to the right place. Or least a good place, to get an answer. 

 

This is a relevant topic posted by @James_N which you might find useful:

 

 

James, @nealmurphy, @Scottychops and @Maurice Kelly I think all have Ecodans and may be able to advise from their own experience. 

 

It’s with cold weather like this that configuration of the heat pump for efficiency is crucial...

Carbon neutral - we need a community to get there! My green tech: Aclara SGM 1411-B smart meter, Chameleon IHD6
juliamc
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I’d say you’ve got those timings scheduled like you would a gas boiler, but they don’t work for a heat pump. When it starts up from cold it’s using a lot of energy to get going, so it’ll get to a point where it’s ticking over nicely then your schedule switches it off. With this happening twice a day you’re not really benefiting at all from having a heat pump! I’d try running it at 16 degrees night and day, ie 24/7 and see how it manages. It should get to a nice tickover and probably use no more electricity than it’s using now. I must add that 16 degrees is amazingly low for central heating and your COP ought to be well over 4 at that temperature.

Please give the constant running a try and report back !!!

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Hi Juliamc. I’ll give it a try and let you know how I get on.

 

Thanks for the advice its much appreciated.

Andy

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Hi Juliamc

I ran the heating all day yesterday (01/12) and looking at the COP this morning the system consumed 57kWh of energy and generated 38kWh of energy. The system is currently running with the weather compensation curve set at 49C / -3c and 36C / -10C. Based on current rates the system consumed just over £15 of electricity yesterday which is an unaffordable cost if ongoing.

I really don’t want to switch the ASHP off completely and revert back to just log burners so any help or advice anyone can provide would be greatly appreciated.

 

 

juliamc
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I wonder if those numbers on the compensation curve are too high for your target temp of 16 degrees ? I’m assuming you mean 36 / 10 not -10 ?

Did you notice if the electric heater icon came on ?

My hp is a Daikin so I’m not sure how auto adapt influences the system. @M.isterW has an Ecodan, any thoughts ?

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Sorry yes its 36 / 10 not -10

juliamc
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What is the outdoor temperature where you are ? I’m in Surrey and it’s -1 deg at the moment. My radiator flow temp is set to be 45 deg, the target room temp is 22. Do you have radiators or underfloor heating?

Thinking more about this: I’m fairly certain the standard design temperatures for heating are 18 deg for bedrooms, 21 for living rooms, 22 for bathrooms. Obviously you can run the hp lower than this if you prefer, but your installer has probably set the curve to give the higher temperatures. 

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I’m in Yorkshire and the temperature here dropped to -4 last night. Judging by the readings from the smart meter the energy consumed so far today the total used will be much higher than yesterday’s. 

juliamc
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Did you see the elec heating icon?

Do you have radiators?

Can you try lowering the curve so it’s not calling for 49 degrees

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The elec heating element is showing and we have new properly sized radiators.

I’ve lowered the curve to 40 degrees.

Is it necessary to have the weather compensation running and if so does the auto adapt setting need to be used in conjunction? These are the current settings.

Once again thanks for your kind assistance.

 

juliamc
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I’ve just found this section from an earlier post about Ecodans, from @M.isterW who has one. First video explains very well the difference heating modes and sounds like auto adapt would be you best choice. 
 

Here are a few more videos that might be useful:

 

A guide to the heating modes - https://youtu.be/RX31v4NoQf4

 

A guide to using the controller - https://youtube.com/shorts/MI_OHZwenBE?feature=share


this is the thread it came from:

 

M.isterW
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How are you measuring energy input and output? The figures measured by the standard Ecodan controller are notoriously inaccurate so don't rely on them.

1992 4 bed detached house. Solar PV + battery, Zappi EV charger, Mitsubishi Ecodan ASHP and i-life2 fan assisted radiators.... No gas 😊
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Thanks juliamc, I’ll take a look at those videos.

Hi M.isterW I’m using the readings from the controller.

Looking just now at my consumption figures on the Octupus app for last Friday the average hourly consumption across the 24 hour period was 2.96kW with the heat pump in constant use over the period. The temperature was set at 16C in auto adapt mode with the weather compensation running in the background. Outside temp through the night was down as low as -4c. Does this level of consumption appear high to you or is this what I should expect going forward?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

juliamc
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I’d say that was massively high if you’re only expecting the house to reach 16 degrees. My system used 32kWh yesterday and the house was around 22 deg, outdoors was btwn 2 and -5 deg. I think mine is using too much so your definitely is.

Can I ask why you’re only targeting 16 deg ?

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We don’t like the house to be too warm and the air too dry plus we’ve got two big wood burners and we like the ambiance they create so hence 16 degrees. I might have got the temperature setting on the low side and so it’s a bit of trial and error, assuming that I can crack the reason for the high heat pump energy consumption. Thanks for sharing your consumption figures as that at least gives me some indication of where it should be. 

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