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JamesPa
@jamespa
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Joined: Apr 3, 2023
Last seen: Aug 5, 2025
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Topics: 17 / Replies: 2676
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RE: Performance of Heat Pumps in Mild Weather

Thanks for that. The ecoforest graph of cop Vs compressor speed explains a lot. Perhaps it even explains how Daikin appear to do a single compressor...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Performance of Heat Pumps in Mild Weather

1.8kW is at 7C, the more interesting figure I think is the min at say 12-15C. That doesn't appear to be specified for the Hitachi, but for the heat p...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Performance of Heat Pumps in Mild Weather

@heatgeek @robs I was going to say exactly what @robs has said. The interesting metric is the ratio between min output at high OAT/low FT and max ou...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Help me keep the faith with my air source heat pump installation

2 port buffer/volumiser is fine, will help with defrost/system volume and no downsides. 2 ports good, 4 ports bad! The general rule for rads is to ...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Ecodan - is there actually such a thing as a 'minimum' flow temp to avoid cycling, and why if so?

The full sentence was "larger radiators = lower flow temperature and larger system volume. The latter certainly would be expected to reduce cycling...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Performance of Heat Pumps in Mild Weather

Thank you for pointing that out, I should have commented on this also (but as you say there is a lot here). I did note this comment, am not disputing...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Performance of Heat Pumps in Mild Weather

Further to the above I discovered a bit more/had an additional thought about Daikin compressors. Firstly Daikin do make their own compressors so its ...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Newbie: utterly confused with my Mitsubishi Zubadan air source heat pump running on 55C set flow temperature

I must say Im also coming to the conclusion that there is a problem of this nature. OP has optimised the initially high flow temperature and its now ...

4 months ago
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Air Source Heat Pumps (ASHPs)
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RE: Ecodan - is there actually such a thing as a 'minimum' flow temp to avoid cycling, and why if so?

Very much agree. I think OP is over-concerned about this because, as you say, cycling is 'designed in'. Also very much agree We may be spli...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Performance of Heat Pumps in Mild Weather

'and thus its capacity' assumes that output is a linear function of modulation frequency. But I dont think thats the key point so lets not argue over ...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
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RE: Ecodan - is there actually such a thing as a 'minimum' flow temp to avoid cycling, and why if so?

Aren't you potentially confusing two things here. OP could of course increase rad size/ volume and reduce ft but that won't change the minimum output...

4 months ago
Forum
Air Source Heat Pumps (ASHPs)
Reply
RE: Ecodan - is there actually such a thing as a 'minimum' flow temp to avoid cycling, and why if so?

It can't once it has got to minimum frequency. If it isn't already at mine frequency then I agree. That would overheat the house. If house ...

4 months ago
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Air Source Heat Pumps (ASHPs)
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