721 hourly rows · MID-class heat meter present: yes
3.04efficiency (COP) over 721 hours, from the heat meter better than 9% of the metered fleet in January 2026
Electricity used
450 kWh
Heat delivered
1369 kWh (heat meter)
Estimate without heat meter
flow sensor 3.05 · temperature model 4.66
Mean outdoor temperature
9.8 °C · 502 space-heating hours · cooling 0 kWh removed (0 kWh electricity), kept out of the COP
Flow temperature at 0 °C outside
34.2 °C (curve slope -0.41 per K)
Flow − return while heating
2.2 K
House needs at −3 °C
3.0 kW (unit rated 6.5 kW) · fit r² 0.22
Hot water
35% of electricity, COP 2.64
warningOnly 2.2 K between flow and return
Circulation pump may be set too high or emitters are undersized for the low flow temperature. Ask the installer to check pump speed.
warningHot water uses 35% of electricity at COP 2.64
Lower the tank target to 45–48 °C, heat water once a day in the warmest hours, and disable weekly legionella cycles unless required.
infoUnit is rated 6.5 kW but the house needs about 3 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.
valueReaching the fleet’s January median (3.69) would have saved about £20 in this window at 0.25 GBP/kWh. An estimate, not a promise.
Day by day
electricity per daydaily COP3.0 floor
Daily COP needs a heat meter; days without one show electricity only.
The installed heating curve
one heating hourfitted curve50 °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.