The reason why plastic items and dishes on the bottom rack of a dishwasher might burn or not get as clean compared to those on the top rack is primarily due to the difference in distance from the heating element and the water spray patterns.
Proximity to heating element: In most dishwashers, the heating element is located at the bottom of the unit. When plastic items or dishes are placed directly above or very close to the heating element, they can get exposed to excessive heat during the wash and dry cycles. This can cause the plastic to melt or warp, leading to burning or deformation of the items.
Water spray patterns: Dishwashers have rotating spray arms at the top and bottom that distribute water to clean the dishes. The water pressure and spray coverage might be stronger and more concentrated at the top, as opposed to the bottom. This can result in better cleaning performance for the items on the top rack compared to the bottom rack.
To optimize the performance of your dishwasher and prevent burning or inadequate cleaning of plastic items and dishes, consider the following tips:
Load plastic items on the top rack: Place plastic containers, lids, and other delicate items on the top rack of the dishwasher, away from the heating element, to avoid direct exposure to heat.
Space out items: Avoid overcrowding the dishwasher, especially on the bottom rack. Leave enough space between items to ensure proper water flow and spray coverage, which will lead to more effective cleaning.
Use lower temperature settings: If your dishwasher has adjustable temperature settings, use lower temperature options for delicate items like plastics to prevent melting or warping.
Pre-rinse plastic items: For heavily soiled plastic items, consider pre-rinsing them before loading them into the dishwasher. This can help remove most of the food particles and make the cleaning process more effective.
Use dishwasher-safe plastics: Ensure that the plastic items you place in the dishwasher are labeled as dishwasher-safe. Not all plastics can withstand the heat and water pressure in dishwashers, so it's essential to use appropriate materials.
By following these tips, you can improve the performance of your dishwasher and ensure that your plastic items and dishes come out clean and undamaged after each wash cycle.