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Daikin Altherma 2

Horsham, West Sussex · Detached · 128 m² · 1983 to 2011 · 7 kW · radiators · installed by Octopus Energy Services

Last 30 days

721 hourly rows · MID-class heat meter present: no
3.90efficiency (COP) over 721 hours, from the heat meter
better than 66% of the metered fleet in January 2026
Electricity used
288 kWh
Heat delivered
1125 kWh (heat meter)
Estimate without heat meter
flow sensor 3.96 · temperature model 4.51
Mean outdoor temperature
12.1 °C · 419 space-heating hours · cooling 0 kWh removed (1 kWh electricity), kept out of the COP
Flow temperature at 0 °C outside
37.7 °C (curve slope -0.42 per K)
Flow − return while heating
3.2 K
House needs at −3 °C
3.2 kW (unit rated 7 kW) · fit r² 0.12
Hot water
15% of electricity, COP 2.65
infoUnit is rated 7 kW but the house needs about 3.2 kW at −3 °C
Oversizing causes cycling in mild weather. Cannot be fixed cheaply now, but the curve and minimum run time can limit the damage.

Day by day

electricity per daydaily COP3.0 floor
electricity, kWh per day08162026-10-08: 6.2 kWh, outside 14 °C2026-10-09: 5.6 kWh, outside 15.4 °C2026-10-10: 9.4 kWh, outside 12.1 °C2026-10-11: 8.6 kWh, outside 13.1 °C2026-10-12: 6 kWh, outside 15.4 °C2026-10-13: 3.2 kWh, outside 18.3 °C2026-10-14: 5.9 kWh, outside 14.8 °C2026-10-15: 5.1 kWh, outside 18 °C2026-10-16: 3.7 kWh, outside 15 °C2026-10-17: 9.3 kWh, outside 11.7 °C2026-10-18: 10.5 kWh, outside 10.9 °C2026-10-19: 9.3 kWh, outside 11.6 °C2026-10-20: 9.2 kWh, outside 11.9 °C2026-10-21: 11.1 kWh, outside 10.2 °C2026-10-22: 9 kWh, outside 13.2 °C2026-10-23: 10.4 kWh, outside 10.5 °C2026-10-24: 11.7 kWh, outside 10.2 °C2026-10-25: 9.9 kWh, outside 11.1 °C2026-10-26: 11.2 kWh, outside 12.6 °C2026-10-27: 7.7 kWh, outside 13.5 °C2026-10-28: 10.2 kWh, outside 10.9 °C2026-10-29: 9 kWh, outside 12.4 °C2026-10-30: 9 kWh, outside 12.5 °C2026-10-31: 9.9 kWh, outside 13 °C2026-11-01: 12.7 kWh, outside 9.2 °C2026-11-02: 11.4 kWh, outside 10 °C2026-11-03: 11.7 kWh, outside 10.1 °C2026-11-04: 16.1 kWh, outside 8.4 °C2026-11-05: 12.3 kWh, outside 9.3 °C2026-11-06: 12.7 kWh, outside 8.2 °C2026-11-07: 10.7 kWh, outside 3.3 °Cdaily COP (heat ÷ electricity)1352026-10-08: COP 3.992026-10-09: COP 3.672026-10-10: COP 3.892026-10-11: COP 3.072026-10-12: COP 4.032026-10-13: COP 3.712026-10-14: COP 3.572026-10-15: COP 4.082026-10-16: COP 3.262026-10-17: COP 3.982026-10-18: COP 3.92026-10-19: COP 3.722026-10-20: COP 4.022026-10-21: COP 3.872026-10-22: COP 4.092026-10-23: COP 3.952026-10-24: COP 4.192026-10-25: COP 4.482026-10-26: COP 4.492026-10-27: COP 4.012026-10-28: COP 4.152026-10-29: COP 4.262026-10-30: COP 3.892026-10-31: COP 3.832026-11-01: COP 4.042026-11-02: COP 3.932026-11-03: COP 3.872026-11-04: COP 3.742026-11-05: COP 3.892026-11-06: COP 3.992026-11-07: COP 2.5810-0810-1210-1610-2010-2410-2811-0111-05
Daily COP needs a heat meter; days without one show electricity only.

The installed heating curve

one heating hourfitted curve50 °C
20304050600246810121416outdoor 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.