737 hourly rows · MID-class heat meter present: yes
3.68efficiency (COP) over 737 hours, from the heat meter better than 50% of the metered fleet in January 2026
Electricity used
785 kWh
Heat delivered
2889 kWh (heat meter)
Estimate without heat meter
flow sensor 3.54 · temperature model 3.74
Mean outdoor temperature
6.5 °C · 696 space-heating hours
Flow temperature at 0 °C outside
37.9 °C (curve slope -0.60 per K)
Flow − return while heating
2.0 K
House needs at −3 °C
6.1 kW (unit rated 16 kW) · fit r² 0.21
Hot water
no hot-water flag in data
warningOnly 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.
seriousCompressor starts about 7.5 times per hour
Short cycling wears the compressor and cuts efficiency. Usual fixes: remove or bypass a buffer, open zone valves, lower the curve, raise minimum run time.
warningUnit is rated 16 kW but the house needs about 6.1 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.
noteOwner’s note on the source site: “Negative heat not reported”
valueReaching the fleet’s January median (3.69) would have saved about £1 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.