I’ve been trying to figure out how much my gas / heating / showers were costing me, but I’ve hit a fairly big discrepancy that I can’t explain.
I have a brand new 28kW/h rated boiler, with 98% efficiency rating, and according to the service manual it will consume 28.57kW/h max worth of gas, or 3.02 m^3 per hour.
I have found through measurement of having a 7 minute hot shower that the boiler was running full whack, consuming exactly at the rate claimed by the guide, 3.02 m^3, but this equates according to my bill to be 34 kW/h.
Where is the extra energy going / being wasted?
| Boiler Stats | Value | Units |
| Gas Max Flow Rate | 3.02 | m^3/hr |
| Max Heat In: | 28.57 | kW/h |
| Max Heat Out: | 28 | kW/h |
| (Calculated Efficiency) | 98.0049002450122 | % |
| Meter Readings | ||
| Used | 12.5 | ft^3 |
| Duration | 7 | min |
| Metric Conversion | 0.35375 | m^3 |
| Flow Rate | 3.03214285714286 | m^3/hr |
| Gas Qualities / Constants | ||
| Calorific Value | 39.7 | |
| Conversion Factor | 1.02264 | |
| kW/h / MJ | 3.6 | |
kW/h at Max Flow = Max m^3/h (3.02) * Calorific Value (39.7) * Conversion Factor (1.02264) / kWh per MJ (3.6)
kW/h at Max Flow = 34.0578889333333