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Poor COP with an Ecodan

 
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Air Source Heat Pumps (ASHPs)
Last Post by Derek M 2 years ago
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 adam_colwell
(@adam_colwell)
Active Member Member
Joined: 3 years ago
Posts: 21
Topic starter 28/11/2023 12:15 pm  

Hi Guys,

I'm hoping you may be able to help. I'm getting (I think) poor COP. In November so far I'm getting a cop 2.39, with heating being a cop of 2.71 and DWH being 1.65. My heating is weather compensation with a flow rate which doesn't go higher then 30c at -2 outside and the DWH is set at 45c with it heating back up when it drops by 12c. All rads are fully open upstairs and downstairs we have underfloor heating. Thermostats are set at 23c with room temperature of around 21c downstairs and upstairs of around 20-19c. I've attached pics of my readings and the model.

20230526 102625
20231127 182816
20231127 182825
20231127 182833

 



   
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 Kev M
(@kev-m)
Noble Member Member
Joined: 5 years ago
Posts: 1276
28/11/2023 4:46 pm  

It does sound a bit low.  My DHW COP is exactly 2 for November.  I run my DHW at what is normally the warmest time, 2pm.

Where in the country are you? 

Do you have a buffer, low loss header or similar on your system?  

Is your heating on all the time or do you have it on and off?

Can you access Melcloud to see what the flow temperatures are doing over time?

The Ecodan measures of consumed and delivered energy are notoriously inaccurate though, especially at low usage.  Your usage is very low - do you have a small or very well insulated house?

 


This post was modified 2 years ago by Kev M

   
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 adam_colwell
(@adam_colwell)
Active Member Member
Joined: 3 years ago
Posts: 21
Topic starter 28/11/2023 5:07 pm  

Hi Kev,

I'm in Wales.

I'm not sure, how would I find out what I have regarding the buffer ect.

The last two days I have and the cop has got worse.

No, I don't have access to the melcloud. How do I get access to that?

I have a 3 bedroom/2 and half bedroom house and it's well Insulated. It's a new build, built this year.

Sorry, I know I haven't been much help there



   
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 @sand
(@sand)
Estimable Member Member
Joined: 4 years ago
Posts: 88
28/11/2023 6:07 pm  

It's an app that you will need to download. 

You will need this bit of kit, check near your FTC.

Screenshot 20231128 175904 Chrome

Lots of information on you tube and the app gives you a step by step guide if I remember correctly.

 



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1003
28/11/2023 6:27 pm  

@adam_colwell Hi Adam. The COP numbers do sound very low given the flow temperatures you are talking about and the insulation values of your house. Do your bills corroborate the COP readings you are reading?

Where abouts in Wales are you? Mark


House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 adam_colwell
(@adam_colwell)
Active Member Member
Joined: 3 years ago
Posts: 21
Topic starter 28/11/2023 6:51 pm  

@bontwoody

Hi Mark,

Yeah my electricity bill does,in total yesterday i used 15kwh , 9kwh of that is heating and water.

I'm in Mid Wales near Aberystwyth.



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1003
28/11/2023 7:08 pm  

@adam_colwell I have a 5kW Samsung, but used to have the same Mitsubishi ASHP as you and I was doing quite a bit better in terms of COP.

9kW for heating and water doesnt sound that bad, I used 9.9 kWh yesterday and 13.5 the day before. I do use an immersion for my hot water but it averages about 3kWh a day. Given you are warm and your usage isnt that high, perhaps the COP given by the monitoring system isnt correct?

My house is old and much leakier than yours but my heating COP is 3.6 for the past two days. How long do you run your heat pump for in a day? I probably do so for about 12 hours.

If your COP is really that low, I think I would start by looking for areas where Im leaking heat such as pipe insulation outside and in the loft. You can view my heat pump stats via the link below. My blog is also linked so you can have a look at my setup.


House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 adam_colwell
(@adam_colwell)
Active Member Member
Joined: 3 years ago
Posts: 21
Topic starter 28/11/2023 7:16 pm  

@bontwoody am the moment, I'm running my heating 24/7, well the thermostats are calling for heat 24/7. The heating is going from working to standby around 4 times an hour.



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1003
28/11/2023 7:21 pm  

@adam_colwell So you are running your heating for twice as long as me with a similar energy usage? It doesnt feel to me like your reporting system is accurate. I have an openenergy monitor system so Im confident my reported COP is accurate. Ball park I would guess you are actually getting a very good COP. You didnt say how big your house was, mine is a two bed bungalow, so if your is larger that would again suggest you are doing a lot better than you think 🙂


House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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 adam_colwell
(@adam_colwell)
Active Member Member
Joined: 3 years ago
Posts: 21
Topic starter 28/11/2023 7:29 pm  

@bontwoody it's a three bed semi detached house. Hopefully it is just reporting it wrong. I'll look at getting the Melcloud app, because by what people are saying, hopefully that is accurate



   
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bontwoody
 bontwoody
(@bontwoody)
Noble Member Contributor
Joined: 4 years ago
Posts: 1003
28/11/2023 7:33 pm  

@adam_colwell I dont have experience with Melcloud but if you can run to putting a heat meter in your circuit it will give you accurate figures. Im pretty confident now that your heat pump is working well 🙂


House-2 bed partial stone bungalow, 5kW Samsung Gen 6 ASHP (Self install)
6.9 kWp of PV
5kWh DC coupled battery
Blog: https://thegreeningofrosecottage.weebly.com/
Heatpump Stats: http://heatpumpmonitor.org/system/view?id=60


   
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1
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 Gary
(@gary)
Reputable Member Member
Joined: 3 years ago
Posts: 350
28/11/2023 9:44 pm  

@adam_colwell I have an Ecodan they don’t modulate down well.  If you are running flow temps that low it will be cycling on and off and that will be why your COP is low.  I have an 8.5 kw unit and I have figured out over the past few years that it can’t run lower than 32C without cycling on and off several times an hour.

You could try pushing your WC curve up a few degrees and see if it cycles less and see if that improves your COP



   
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