Design Smart’s principal design engineer was intimately involved in the development of the very first DishDraw, and was directly responsible for the design of the first Spray Arm for the product.
During the testing of the initial Spray Arm design in 1996, it was discovered that a small amount of additional weight added to the Spray Arm improved the wash performance. However, the Spray Arms design was optimised to ensure good wash performance without this weight being needed. The reason is that there is a critical balance that needs to be achieved between the water pressure forces of the underside Wash Impellor aperture and the top side Spray Arm hole apertures (or nozzles) needed for the dish washing water jets. If this is not optimised, leakage around the underside Wash Impellor aperture increases and this is detrimental to the water jets’ pressure; hence the wash performance.
It would appear to us, having purchased a series 7 DishDrawer in 2019 for our then property that this knowledge was either temporarily lost or overlooked in the organisation that once employed our engineer. You can achieve significant wash performance increase by adding weight to the top of your older Series 7 DishDrawer Spray Arms.
You need a little more weight than what was initially used on the original Spray Arms to achieve the best results. A simple Hot Melt glue gun does a good job of adhering a weight to the centre top of the Spray Arm. An original (1967 version) 50 cent piece was used to do the job originally. It was only 13 grams. However, an American $1 coin (23 grams) or better still a U.K. Churchill coin (28 grams) does a better job when glued to the top of the 2019 Series 7 Spray Arm design. See photos for further clarity.
However the good news now is that they appear to have got the memo on this and the latest series 7 DishDrawer that we purchased for our new property in December 2022 has a rectified Sray Arm design which now weighs 147 grams in total on its own and the wash performance is good once again.
In the meantime, this original light weight Series 7 Spray Arm has caused many people say to me that the wash performance of a DishDrawer is poor and would never buy one again. That is sad as it is a really good product if you get these early Series 7 Spray Arms sorted out as detailed here. Hope this information helps as we certainly can’t live without a DishDrawer having briefly gone back to a drop-down door model.