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Vaillant Arotherm+

Wetherby, West Yorkshire · Detached · 100 m² · 1983 to 2011 · 7 kW · radiators · installed by Clear Skies Energy Ltd

5 Jan – 4 Feb 2026 (winter reference)

721 hourly rows · MID-class heat meter present: yes
3.11efficiency (COP) over 721 hours, from the heat meter
better than 14% of the metered fleet in January 2026
Electricity used
777 kWh
Heat delivered
2419 kWh (heat meter)
Estimate without heat meter
flow sensor 3.05 · temperature model 3.14
Mean outdoor temperature
4.3 °C · 437 space-heating hours · cooling 2 kWh removed (5 kWh electricity), kept out of the COP
Flow temperature at 0 °C outside
36.0 °C (curve slope -0.04 per K)
Flow − return while heating
3.5 K
House needs at −3 °C
6.8 kW (unit rated 7 kW) · fit r² 0.32
Hot water
12% of electricity, COP 2.34
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 £31 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 day029582026-01-05: 58.3 kWh, outside -1.4 °C2026-01-06: 54.5 kWh, outside 0 °C2026-01-07: 43.9 kWh, outside 3.5 °C2026-01-08: 55 kWh, outside 0.5 °C2026-01-09: 46.1 kWh, outside 2.8 °C2026-01-10: 49.6 kWh, outside 0.3 °C2026-01-11: 44.3 kWh, outside 3 °C2026-01-12: 27.2 kWh, outside 8.7 °C2026-01-13: 30.3 kWh, outside 5.8 °C2026-01-14: 44 kWh, outside 2.6 °C2026-01-15: 39.4 kWh, outside 4.1 °C2026-01-16: 30.3 kWh, outside 3.9 °C2026-01-17: 25.2 kWh, outside 5.9 °C2026-01-18: 23.8 kWh, outside 5.6 °C2026-01-19: 23.5 kWh, outside 6.9 °C2026-01-20: 22 kWh, outside 7.9 °C2026-01-21: 27.2 kWh, outside 6.8 °C2026-01-22: 25.5 kWh, outside 6.2 °C2026-01-23: 26.2 kWh, outside 6.6 °C2026-01-24: 27.3 kWh, outside 6.1 °C2026-01-25: 18.7 kWh, outside 5 °C2026-01-26: 1.1 kWh, outside 3.1 °C2026-01-27: 2.7 kWh, outside 4.8 °C2026-01-28: 7.2 kWh, outside 2.5 °C2026-01-29: 6.7 kWh, outside 3.7 °C2026-01-30: 6.2 kWh, outside 4.1 °C2026-01-31: 1.6 kWh, outside 6.6 °C2026-02-01: 1 kWh, outside 6.4 °C2026-02-02: 2.5 kWh, outside 5.4 °C2026-02-03: 11 kWh, outside 2.9 °C2026-02-04: 0.4 kWh, outside 2.2 °Cdaily COP (heat ÷ electricity)1352026-01-05: COP 2.422026-01-06: COP 2.492026-01-07: COP 2.922026-01-08: COP 2.362026-01-09: COP 2.582026-01-10: COP 2.392026-01-11: COP 2.682026-01-12: COP 3.332026-01-13: COP 3.32026-01-14: COP 2.682026-01-15: COP 2.972026-01-16: COP 3.022026-01-17: COP 3.62026-01-18: COP 3.972026-01-19: COP 3.512026-01-20: COP 4.192026-01-21: COP 3.672026-01-22: COP 3.892026-01-23: COP 3.832026-01-24: COP 3.732026-01-25: COP 3.572026-01-26: COP 3.372026-01-27: COP 4.92026-01-28: COP 4.122026-01-29: COP 4.522026-01-30: COP 4.522026-01-31: COP 5.012026-02-01: COP 3.622026-02-02: COP 5.052026-02-03: COP 4.4801-0501-0901-1301-1701-2101-2501-2902-02
Daily COP needs a heat meter; days without one show electricity only.

The installed heating curve

one heating hourfitted curve50 °C
2030405060-6-4-2024681012outdoor 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.