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Daikin Altherma 3

Southampton, Hampshire · Detached · 185 m² · 1983 to 2011 · 9 kW · radiators · installed by Octopus Energy Services

1–31 Dec 2025

732 hourly rows · MID-class heat meter present: no
3.40efficiency (COP) over 732 hours, from the heat meter
better than 34% of the metered fleet in January 2026
Electricity used
660 kWh
Heat delivered
2243 kWh (heat meter)
Estimate without heat meter
flow sensor 3.36 · temperature model 3.72
Mean outdoor temperature
7.7 °C · 397 space-heating hours · cooling 1 kWh removed (0 kWh electricity), kept out of the COP
Flow temperature at 0 °C outside
36.2 °C (curve slope -0.19 per K)
Flow − return while heating
4.2 K
House needs at −3 °C
6.5 kW (unit rated 9 kW) · fit r² 0.10
Hot water
9% of electricity, COP 3.09
infoNo configuration faults detected in this window
Keep the current settings. We will alert you if efficiency drifts.
valueReaching the fleet’s January median (3.69) would have saved about £13 in this window at 0.25 GBP/kWh. An estimate, not a promise.

Day by day

electricity per daydaily COP3.0 floor
electricity, kWh per day028552025-12-01: 11.6 kWh, outside 10.5 °C2025-12-02: 13.9 kWh, outside 7.5 °C2025-12-03: 22.7 kWh, outside 6.7 °C2025-12-04: 21.9 kWh, outside 6.8 °C2025-12-05: 27.2 kWh, outside 5.7 °C2025-12-06: 12.3 kWh, outside 10.6 °C2025-12-07: 13 kWh, outside 11.6 °C2025-12-08: 6.9 kWh, outside 12.4 °C2025-12-09: 8.9 kWh, outside 12.5 °C2025-12-10: 10.4 kWh, outside 10.9 °C2025-12-11: 17.2 kWh, outside 9.3 °C2025-12-12: 15.2 kWh, outside 9.6 °C2025-12-13: 23.7 kWh, outside 5.9 °C2025-12-14: 16.7 kWh, outside 9.2 °C2025-12-15: 13.2 kWh, outside 10.6 °C2025-12-16: 18.5 kWh, outside 8.6 °C2025-12-17: 23.3 kWh, outside 6.3 °C2025-12-18: 13.3 kWh, outside 10.9 °C2025-12-19: 19 kWh, outside 8.3 °C2025-12-20: 20.7 kWh, outside 7.2 °C2025-12-21: 16 kWh, outside 9.2 °C2025-12-22: 16.1 kWh, outside 9.5 °C2025-12-23: 16.2 kWh, outside 7.3 °C2025-12-24: 33.3 kWh, outside 5 °C2025-12-25: 29 kWh, outside 3.7 °C2025-12-26: 37.8 kWh, outside 3.5 °C2025-12-27: 31.4 kWh, outside 5.3 °C2025-12-28: 23.6 kWh, outside 6.6 °C2025-12-29: 33.3 kWh, outside 4.5 °C2025-12-30: 36.9 kWh, outside 4.1 °C2025-12-31: 55.2 kWh, outside -0.1 °C2026-01-01: 2.3 kWh, outside -0.1 °Cdaily COP (heat ÷ electricity)1352025-12-01: COP 4.482025-12-02: COP 3.442025-12-03: COP 3.212025-12-04: COP 3.352025-12-05: COP 3.342025-12-06: COP 4.52025-12-07: COP 4.292025-12-08: COP 5.152025-12-09: COP 4.682025-12-10: COP 4.32025-12-11: COP 3.162025-12-12: COP 3.632025-12-13: COP 3.122025-12-14: COP 3.552025-12-15: COP 4.082025-12-16: COP 3.982025-12-17: COP 3.182025-12-18: COP 4.532025-12-19: COP 3.462025-12-20: COP 3.382025-12-21: COP 3.972025-12-22: COP 4.052025-12-23: COP 3.782025-12-24: COP 3.222025-12-25: COP 3.212025-12-26: COP 2.932025-12-27: COP 3.362025-12-28: COP 3.372025-12-29: COP 3.052025-12-30: COP 3.022025-12-31: COP 2.322026-01-01: COP 2.6812-0112-0512-0912-1312-1712-2112-2512-29
Daily COP needs a heat meter; days without one show electricity only.

The installed heating curve

one heating hourfitted curve50 °C
2030405060-3-113579111315outdoor temperature, °Cflow temperature, °C
Each point is one hour of space heating. Lower and flatter is cheaper; well-set radiator systems sit around 35–42 °C at 0 °C outside.
Public system published by its owner on HeatpumpMonitor.org. Cycling (starts per hour) comes from the site’s 365-day statistic. Findings use installer rules of thumb; see methodology.