Short cycle efficient?
It could be, but short cycles did not always mean low water use and unless the wash action and particle filtration were effective, often times not. Another problem with low water use was the fact that even very hot water was cooled to below optimum wash temperatures when it came in contact with the room temperature dish load and tank. The Ling-Temco did not have a detergent dispenser so it could not have a pre rinse to help warm everything before the wash. Old detergents were not able to do their best at lower water temperatures and even today's detergents designed for lower water temperatures need a longer wash period than many early dishwashers provided to do their best cleaning. My KD2P KitchenAid, their first top load portable, has a cycle that starts with a one minute flush that fills and drains to help warm the sump and the cast iron pump, then a 5 minute wash, IIRC, and two rinses of one minute each. With the purge, it uses about 8 gallons of water which is far more than the Ling-Temco, but it is a larger machine and will hold things that will not fit inside the L-T. The performance is greatly improved by starting the process with one or two of the after rinses, which increases water consumption, then raising the lid as little as possible to add the detergent before restarting so that everything is nice and hot for the wash, but it is not a cycle for dried or cooked on food soil. Either the machines were run after each meal or dishes were very well rinsed if they had to wait to be washed. The double wall porcelain tank of the KD2P provides thermal and sound insulation, but even 2.3 gallons (the amount of each fill)of very hot water will drop 30 to 40 degrees when it comes in contact with the tank and dishes at room temperature. Factor into this that many of the older dishwashers were installed against outside walls (usually there was a window over the sink) that could get very cold in the winter, and the thermal loss was even greater. Some older machines heated the water before it went into the dishwasher, but had no provision for heating the water once it was in contact with the dishes and that electrically heated 2 gallon tank which kept water at 180F 24/7 was not insulated so that was not efficient. Some (Hotpoint was the first) had a heating element in the sump. While it was energized throughout the cycle in many cases, the short washes did not have thermal holds on the timer to make sure the water stayed hot during the wash. I think Hotpoint was the first to have a detergent dispenser which allowed for two washes and gave the detergent for the first wash some protection. This allowed the initial 45 second flush to be very effective because the dishwasher filled from the top center of the tank where the water caused a small finned disc to spin. The shower this created not only warmed the whole tank and load, but also flushed some soil down the drain before washing began. Most of the machines that used an impeller wash action filled with around 6 quarts of water for each phase of the cycle. Finally, except for some double wall D&M portables, thermal insulation was hardly used until the mid to late 70s, although by then most dishwashers except for the cheapest bol machines had detergent dispensers which allowed for a fill or two to heat the machine and contents before the detergent was dispensed in the main wash.
