We use a dehumidifer when rv is in 'storage' in our backyard. Mostly during the rainy spring and late fall. With our model the air going into the dehumidifer must be above a certain temperature (found this in our manual). So when the air temp is too low we set up a small cube heater to warm the air just in front of the dehum. Note we are not trying to raise the temp in the whole rv. Use the dry crystals in the bedroom and cab area and the dehum is in the center kitchen. We do not use anything when rv is occupied. Oh, and when in storage, we make sure every cupboard and cabinet and drawer is slightly ajar so moisture doesn't build up and create mold. Here in Vancouver, Canada we can get an awful lot of rain, must empty the dehum often. And we check the unit at least twice a day with the devices running.