Last seen: Feb 6, 2026
Hi @sheriff-fatman Cycling at 5C and below is usually defrosts. The other cause can also be an internal thermostat cycling the heat pump due to the...
Hi @sunandair I hope the annotated image and description below helps describe what is happening. A) Output falling d...
Hi @cathoderay Yes the bulk of the energy comes from the already heated water, you can see that as the yellow area above the blue dashed line in th...
Hi @sheriff-fatman Freeze Stat is to stop the water in the outside pipework freezing when the heat pump is not operating (heating), it doesn't caus...
Hi @sunandair We also have a Mitsubishi Ecodan but we also have OEM's energy monitoring kit installed, so have access to data with far greater accu...
Hi @green_fox As a we have a PUZ-WM80VAA with FTC7 (the 8kW R290 Ecodan) I might be able to add some Mitsubishi specific info... As J...
Good graphs @cathoderay but is the axis labelling wrong? X-axis (0-18) should be OAT and y-axis (0-10) COP? Interesting that the COP advantage of cont...
@cathoderay yes I am familiar with SQL. Interesting numbers... If there was no setback we have 4.12 kWh and a mean COP of 5.21, so energy in of 0.791 ...
Hi @cathoderay - this is a good discussion! I feel like we might be making some good progress in answering the fundamental setback question. ...
Hi @cathoderay The 13kWh is as they say my bad, I was calculating 3 hour periods for the reheat and mistakenly only multiplied by 3 here, so 13 ...
The predicted values are based on assumptions and it is these assumptions that need testing IMHO. Your 9-10 April graph shows that prior to your se...
I'm not James but here's some thoughts... Have you tried to control for solar gain? And what about controlling for wind chill effects (speed an...
Latest Posts
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RE: If a heat pump can only heat DHW to 50C then what? Issue with 18KW Heliotherm heat pump
Hi, Nothing yet. I've asked customer to measure flow...
By errmm , 5 hours ago
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RE: High Temp Heat Pumps for fast warm-up of house
I don't know exactly how long it takes to heat up (and ...
By JamesPa , 7 hours ago
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RE: Need help maximising COP of 3.5kW Valiant Aerotherm heat pump
OK. What Im seeing looks fairly normal TBH: 1 start ...
By JamesPa , 7 hours ago
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RE: Vaillant Tech Support Flagged Low DT: UFH Return Cold, Suspected Zero Flow
@editor thanks for the tips which I will try before cal...
By DavidB , 9 hours ago
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RE: Daikin 6kw setup with Dixell controller
@jamespa Many thanks for your reply, a very detailed an...
By CraigH , 9 hours ago
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RE: Exploring the role of alternative clean heating solutions - Government Consultation
Despite reservations, I found some time to respond to t...
By Rusty , 9 hours ago
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RE: New Vaillant aroTherm Plus in black - When will it come to the UK?
@crankplus, nope, still not, and I've followed up with ...
By Mars , 9 hours ago
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RE: Octopus Cosy Heat Pump Owners & Discussion Thread
@agentgeorge Probably, but temperature change at -10 ha...
By AndrewJ , 10 hours ago
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RE: External wall insulation - your experience
To be clear, my experience was very positive. The journ...
By Batpred , 12 hours ago
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@foxesfan Re: ‘Servicing’ as @editor has covered in his...
By Toodles , 12 hours ago
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RE: A Smarter Smart Controller from Homely?
@benson No idea why mine doesn’t work, all I see on ...
By Papahuhu , 13 hours ago
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RE: Battery sizing - How low can you go!
It seems I am seeing something similar to what you do, ...
By Batpred , 14 hours ago
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RE: Gaslighting in the heat pump industry – has anyone else experienced this?
Don’t know if this is relevant to this thread, but my A...
By Gruff2001 , 14 hours ago
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RE: Bosch CS5800i 5kW - Experience So Far
@majordennisbloodnok While getting Home Assistant runni...
By Steelbadger , 1 day ago
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RE: MCS - BS EN 12831-1:2017 – Heat Loss Survey
Since May 2025 it no longer a requirement in England to...
By JamesPa , 1 day ago
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RE: Air source heat pump roll call – what heat pump brand and model do you have?
Forum Handel @jancold Manufacturer: Daikin Model: E...
By Jancold , 1 day ago
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RE: Octopus Cosy 12 Heat Pump Regret: Incredibly Loud, Poor Heating & Constant Hum - Help!
@harriworld it was roughly 3am for an hour as that’s ...
By L2jad , 1 day ago
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RE: Hoped for improvements not being realised on my Mitsubishi heat pump
I have been wondering that myself. The fact is that, ...
By JamesPa , 1 day ago
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RE: Filtering Tap Water – Share Your Setup for Cleaner, Better-Tasting Water
I remember when I was in my early 20s I was introduced ...
By Majordennisbloodnok , 2 days ago
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RE: Setback savings - fact or fiction?
But if it is recorded an an integer, which it seems it ...
By cathodeRay , 2 days ago
