Energy Saving at Pico Technology

A few months ago we wrote about the water heater, and gave some figures for its energy consumption.  That was with the heater in use, with water being drawn off regularly.  Now that the heater has been replaced by a new wall-mounted one, we have just done an experiment with the old one to see how much energy it uses when no water was drawn off.

We filled the heater with cold water, switched on the power and left it alone for about six hours.  The energy consumed in this time was 2.34 kWh.  This amounted to an average power input of 376 W, compared to the figure of 488 W that we obtained when the heater was in use.  So the difference in the figures, 112 W, is the amount of power needed to heat our drinks.  That means that about 80% of the energy is being used to heat the room, and only 20% is going into our drinks.

We can't measure the energy input to the new heater (Instanta WM7 SS) because the cabling is buried in the wall, but the manufacturer claims that it uses 120 W when idling.  This would be a big improvement over the 376 W used by the old heater (although that figure was slightly pessimistic as it included the energy taken to heat up from cold).