Renewable Heating Hub Heat Pump Forums

Search with Wattson
Forums
Renewable Heating
Air Source Heat Pum...
Daikin Altherma 3 1...
 
Notifications
Clear all

Joining the Renewable Heating Hub forums is completely free and only takes a minute. By registering you’ll be able to ask questions, join discussions, follow topics you’re interested in, bookmark useful threads and receive notifications when someone replies. Non-registered members also do not have access to our AI features. When choosing your username, please note that it cannot be changed later, so we recommend avoiding brand or product names. Before registering, please take a moment to read the Forum Rules & Terms of Use so we can keep the community helpful, respectful and informative for everyone. Thanks for joining!

Daikin Altherma 3 11 kW Heat Pump – More Efficient But Not Necessarily Cheaper To Run?

 
Air Source Heat Pumps (ASHPs)
Last Post by JamesPa 2 months ago
2 Posts
2 Users
0 Reactions
266 Views
RSS
 Optimistic Optimiser
(@optimistic-optimiser)
New Member Member
Joined: 2 months ago
Posts: 4
Topic starter 07/03/2026 8:07 pm   [#2873]

I have a Daikin Altherma 3 11kw heat pump which was installed by Octopus about 15 months ago.  Octopus set it up to follow the weather curve but also referencing the Madoka thermostat.  Over time I have refined the weather curve to try to improve the efficiency (COP c. 3.3 based on the cumulative information from the Madoka MMI) with some success.  Last year the heating and hot water consumption was about 4000 kwh.  I am trying to convince myself that I should change from the current setup to pure weather compensation, but the thing that is stopping me is I understand (please tell me if this is wrong) that the 11kw Daikin consumes a minimum of about 900w when the compressor is working and I understand that the aim is to keep the compressor working (heating low and slow). If you were the middle of winter I can understand that this might be fine, but 900w multiplied by 24 hours is 21.6kwh per day as a minimum.  My consumption for a day earlier this week when the weather was between about 6 degrees and 8 degrees  for the whole day was 16kwh.  These numbers suggest to me that pure weather compensation used all through the year would be more expensive but quite possibly give me a higher COP/SCOP. 

What is it that I am missing?

 


This topic was modified 2 months ago by Mars

   
Quote
JamesPa
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 4864
07/03/2026 10:31 pm  

Posted by: @optimistic-optimiser
↑

What is it that I am missing?

The fact that when the demand (ie house loss) is less than the minimum that the heat pump can turn down to' the heat pump will cycle on and off so that on average the demand and output are matched

Like this (from my heat pump) between about 11am and 1800 on the first day and after 11am on the second day.

 

 

image

This post was modified 2 months ago 3 times by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
ReplyQuote
Forum Jump:
  Previous Topic
Next Topic  
Share:

Join Us!

Latest Posts

Members Online

Click to access the login or register cheese
x Powerful Protection for WordPress, from Shield Security PRO
This Site Is Protected By
Shield Security PRO →