A like-for-like replacement of our 10-year-old Zanussi model...
Our old dishwasher, after at least one repair some years ago (photos of the expired Zanussi DW24), started failing to fill but turning the heating element on anyway 2009/12/10, which I assumed meant that the logic was failing. The pump had been getting weaker for some time too, so the money to buy a replacement had been put to one side...
Though less urgent than replacing our washing machine we still wanted a replacement fairly quickly, so having done a quick survey of the alternatives I selected us another Zanussi (AAA-rated), more-or-less a direct replacement for our expired model, but with the addition of an 'eco' programme.
The astonishing thing to me is that a decade of dishwasher development doesn't seem to have made an enormous difference to (energy) efficiency. For example, the main and quick washes seem from the manual as if they will use more-or-less the same energy and water as the just-expired appliance.
What we seem to have gained with the new model is a greater variety of programmes which presumably allows more efficient use in its own right for users that take the time to choose the correct cycle. We also get a cooler (50°C) 'eco' wash that washes for longer to use only the energy of the quick wash while apparently managing the thoroughness of the main (65°C) wash and the convenience of a thermal dry.
We also gain a 'delay' button to help reduce electricty costs and carbon emissions, and an even-more-intensive (70°C) pot-and-pans wash...
I shall be evaluating the wash performance vs energy consumption!
|Programme||Wash Temp||Wash Time||Energy Use||Inlet Temp||Comments|
|Intensive||70°C||75m^||1.7kWh*||10°C||Did a reasonable job of some baked-on food on a glass dish, and got a well-used tea mug pretty clean too, though I'm not sure that it's worth twice the energy of 'ECO'.|
|Normal||65°C||110m^||1.5kWh*||10°C||Wash quality (and drying) was fine overnight on a mixed full load (having first done a prewash/rinse and emptied the filter).|
|Quick||65°C||30m^||0.9kWh*||10°C||Wash quality (and drying) was fine overnight on a smallish load (having first done a prewash/rinse and emptied the filter). Another moderately-full mixed run during the day used 0.8kWh and did not quite clean a peanut-butter jar.|
|ECO||50°C||130m||0.9kWh*||10°C||Seems to be a better wash/rinse than the quickwash on the old machine, with better drying if time is left after the cycle, eg overnight.|
|Prewash||cold||11m||~0.02kWh||10°C||Tiny amount of energy (less than boiling the water for a small cup of tea) to get most of the crud off your plates before starting the wash proper!|
I expect that ECO will be our usual overnight cycle, with the occasional Intensive/Normal 'maintenance' wash, and 'Quick' if we need to catch up during the day.
I will use the Prewash during the day when necessary to prevent food from drying on, and before a Quick wash to ensure that milk is rinsed off first in cold (as an immediate hot wash may cause it to stick worse to dishes), and to empty the filter before a full wash of plates, etc, are especially dirty.
I measured the (electrical) load profile of the dishwasher. When idle (ie just front-panel lights on) it consumes ~2W. When filling it consumes ~9W. When washing, ie pumping water around inside, it consumes ~100W. When heating (while washing/rinsing), it consumes ~2200W (peak 2285W).
For the "ECO" 50°C wash, with at 13°C water inlet temperature, basic behaviour was:
(Note: the instruction manual seems to claim one more rinse than I observed.)
Thus, two bursts of ~0.4kWh consumption (>2kW) at 20m and 60m for ~10m each, the first 70m otherwise being a fairly constant ~100W, and the last ~60m being a fairly constant ~2W.
Fairly similar (though more bursty with lower total consumption) to the Defy Dishmaid "Normal Wash" 60°C for example.
The machine that serves this site is powered by local off-grid solar and wind renewable energy as far as possible, backed up by on-grid renewables including as of 2008/03 a substantial grid-tie solar PV system, and 100% renewable grid power (mainly wind) from Ecotricity; power draw is ~4W.
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Copyright © Damon Hart-Davis 2007-2013.