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Confused by Flow Rates

 
Air Source Heat Pumps (ASHPs)
Last Post by Mars 1 hour ago
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 phil bell
(@phil-bell)
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Joined: 8 months ago
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Topic starter 12/11/2025 5:56 pm  

So I've watched the latest video on youtube, and there was a lot of talk about flow rates, a pretty confusing episode and i've watched it twice now.  My Daikin unit literally makes every effort in the world to crash my flow rate down to 7ltr pm, it can happily run much much higher when it first runs, circa 25ltr's pm but will actively look to dive that down low.  Also at those high flow rates it drinks juice.  

So we have nice fat pipework, big rads etc.  They all seemed to suggest that a system had some kind of mythical flow rate that sounded high, hence more pumps as a lazy solution.  Daikin seem to have designed their heat pumps to crash flow rates.  I've seen loads of Daikin Altherma users who see this behaviour.  So has Daikin literally built really bad heat pumps that are incapable of peak efficiency?    

We run a system that is on all day every day and we see low power draw so it seems to be efficient.  The Dainkin energy reporting suggests we are comfortably seeing a COP of 3.9  With a DT target of 4

Any more thoughts on what i'm clearly not getting.


This topic was modified 1 hour ago 2 times by Mars

   
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Mars
 Mars
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12/11/2025 9:40 pm  

I’ll defer to @pirate-rich and @nigel-d and @ian-e on this one…


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