Notifications
Clear all

Sudden drop in COP

9 Posts
4 Users
1 Reactions
186 Views
(@ecobaker)
Trusted Member Member
228 kWhs
Joined: 3 months ago
Posts: 30
Topic starter  

I've had a sudden drop in COP, from around 3.8-4.4 a few weeks ago, to 2.4-3.0 recently. Any thoughts as to why?

I have a Samsung 8kw ASHP that for the last month or two I've only been using for DHW. I don't have any advanced monitoring, just the energy use and generation output by the unit itself. Over the last week the COP has been way down and I'm not sure why. 

I heat up the DHW once a day between 2pm and 3:30pm, 200L water tank with 3m square heating coil. The unit switches into quiet mode when DWH is active. It's not a heavy use set up, one shower a day and maybe some washing up. 

I don't have the heating on this time of year and don't want to turn it on to see what that is running at. 


   
Quote
(@bontwoody)
Noble Member Contributor
2943 kWhs
Joined: 2 years ago
Posts: 418
 

My guess would be that the unit is measuring combined COP for heating and hot water. Therefore because now you are only heating water at a lower COP than heating your average drops. 

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


   
Mars reacted
ReplyQuote
sjn
 sjn
(@sjn)
Eminent Member Member
250 kWhs
Joined: 3 months ago
Posts: 18
 

@ecobaker,

Posted by: @ecobaker

I don't have any advanced monitoring, just the energy use and generation output by the unit itself.

How do the energy use and generation output differ between the good COP and bad COP weeks? Is it that the energy used has increased or the energy generated has decreased to give you the lower COP?

My Samsung Gen6 8kw had a bit of brain fade earlier in the year when the recorded energy generation figures became ridiculously high - 1,398kWh for one week in February. The energy consumption was recorded as a (more believable) 90kWh, so a fantastic COP of over 15 🤗 . I knew something was really wrong when I saw that the recorded weekly operation time for that week was 524 hours - around 75hrs a day. Samsung Technical Support talked me through a reset of the Wired Remote Controller and that appeared to sort the issue.


   
ReplyQuote



(@ecobaker)
Trusted Member Member
228 kWhs
Joined: 3 months ago
Posts: 30
Topic starter  

@bontwoody The thing is I have been using it for only DHW for a month or two, i was getting higher cop just on the hot water, so it can’t be that I’ve turned off the heating.


   
ReplyQuote
(@ecobaker)
Trusted Member Member
228 kWhs
Joined: 3 months ago
Posts: 30
Topic starter  

@sjn Okay so it was a software issue. It appears my energy use is going up, but my energy generation is staying about the same according to the numbers.


   
ReplyQuote
sjn
 sjn
(@sjn)
Eminent Member Member
250 kWhs
Joined: 3 months ago
Posts: 18
 

@ecobaker Yes, it must have been a software bug disrupting my historic energy numbers. I haven't looked at them recently so I should check to see if they are still ok.

Your generation staying about the same makes sense for a consistent use of DHW so it is the increased usage that is unexpected.

One thing I have noticed is that there is some rounding going on with the displayed energy numbers - the sum of the energy figures for each day does not add up to the displayed total for the week. I wonder if with DHW only the usage and generation will be quite low so the rounding errors may have a bigger significance to your COP calculations, possibly amplifying any week to week changes due to different outside air temperature 🤔 .


   
ReplyQuote
 HCas
(@hcas)
Estimable Member Member
304 kWhs
Joined: 2 months ago
Posts: 41
 

@sjn I've seen this on other brands as well. Rounding for small consumption (for instance only hot water) really messes up the accuracy. 
Another thing we've seen is that some manufacturers just add on a flat energy use per hour (during periods when the heat pump is not running). Maybe Samsung did a software update recently and started doing this as well?


   
ReplyQuote
(@ecobaker)
Trusted Member Member
228 kWhs
Joined: 3 months ago
Posts: 30
Topic starter  

@sjn i've actually been doing calcualtions on a daily basis, so a rounding error would make a big difference.


   
ReplyQuote
(@ecobaker)
Trusted Member Member
228 kWhs
Joined: 3 months ago
Posts: 30
Topic starter  

@hcas Thing is I've not updated the software, that's actually quite hard to do with Samsung as its not directly connected to the internet.


   
ReplyQuote





Share:

Join Us!

Latest Posts

Heat Pump T-Shirts

Delta T Sounds Greek to Me
x  Powerful Protection for WordPress, from Shield Security
This Site Is Protected By
Shield Security