Is it necessary to inflate the vacuum drying oven during operation?

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Recently, two vacuum dryers were installed. Inside these dryers, drying trays are used to dry chemical intermediates; the material is in the form of fine crystalline powder, with a moisture content of around 15–20%. The melting point of the dried product is approximately 85°C. High-temperature air-source heat pumps are used to generate hot water, with the temperature of the hot water tank controlled at 65°C. This hot water is then pumped via a circulation pump into the coils inside the vacuum dryers. The temperature inside the vacuum dryers is around 55°C. If the temperature becomes too high, the high moisture content of the material can cause its melting point to drop, resulting in partial melting of the material. The vacuum dryers use water jet pumps to create a vacuum, with a vacuum level of approximately -0.092 to -0.095. When the vacuum dryer starts operating, it remains completely sealed. The drying process takes about 20 hours. Once drying is complete, the door of the vacuum dryer is opened, and a large amount of condensed water flows out from the bottom of the dryer. The moisture content of the materials in the lowest layers is particularly high; they are still very wet, meaning they have not been dried properly ； I asked the manufacturer of the vacuum drying oven, and they said that air should be allowed to flow inside the oven. So, I slightly opened the vent valve of the oven to let in a little air; as a result, the vacuum level dropped to between -0.09 and -0.092, which increased the drying time to around 24 hours. The advantage of this approach is that when the oven door is opened after drying, there is no condensed water at the bottom, and the materials on the bottom trays are just as dry as those on the upper layers. This can be understood as follows: the water vapor that evaporates during drying is drawn away by the vacuum pump together with the little air that enters through the vent valve, preventing the water vapor from condensing due to the lower temperatures on the walls and bottom of the oven caused by insulation effects. I would like to ask for your advice on this: In the drying process of materials similar to those mentioned above, is it necessary to continuously introduce a small amount of air into the vacuum dryer, so that the water vapor generated can be removed along with the air by the vacuum pump? ； If a little air is not introduced, how can we prevent the water vapor that evaporates from recondensing into liquid water on the vessel walls and bottom, where the temperature is slightly lower than that at the center? If a small amount of air is not introduced and the vacuum level of the vacuum pump is increased to around -0.098, can this prevent the formation of condensation water at the bottom of the drying oven? I would be very grateful if you could give me some advice.