Quote:
Originally Posted by Francesca Knowles
There are four sets of numbers there (see below)...
Quote:
Energy consumption @amb temp 25°C (kWh/24h) 1.9
Energy consumption 12V @amb temp 25°C (Ah/24h) 220
Energy consumption 230V @amb temp 25°C (kWh/24h) 1.9
Energy consumption gas (g/24h) 265 g/24h
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The last three rows correspond to cooling on the three power sources: 12VDC, AC power (in Europe, with their 230V power), and
propane gas. None of them include power for controls, because there isn't any - this model (the RF 60) does not have electronic controls.
This model has 110W heaters (AC and DC), which would use 110 W x 24 h/day = 2.64 kW-h/day if running continuously, so it appears to cycle on and off to maintain the set temperature, being on for about 1.9/2.64 = 72% of the time (17.3 hours/day).
The DC row expresses consumption in amp-hours (a useful number for a user considering how quickly their
battery will be exhausted) and reflects always-on operation (because as the spec sheet explains the thermostat works only in AC and
propane modes) at 12V. This corresponds to
220 Ah/24h x 12V = 2.64 kWh/24h, or
110 W x 24 h = 2.64 kWh/24h
The
energy content of propane is 50.35 kJ/g, so the energy consumption per day on
propane (assuming that their spec is for propane, not butane) is
50.35 kJ/g x 265 g/24h / 3600 kJ/kWh = 3.7 kWh/24h
The burner uses 11 g/h, which would be 50.35 kJ/g x 11 g/h / 3.6 kJ/Wh = 154 W
That's much higher consumption than with electricity. Propane operation is
effective, because a lot of energy is carried in a filled propane tank compared to a similar mass of charged
battery and the burner has higher output than the 110 watt electric heaters, but it is not very
efficient, presumably because the heat doesn't transfer very efficiently into the
refrigerator system.
By the way, this sample model (RF60) should have similar performance to small RV refrigerators, but it is not for use in RVs.