Perry525 said:Because cold air drops, homes, offices factories, caravans have their air con units on high, but cars do not. Cars usually have theirs at waist height and the air is blown from vents in he dash board and at floor level.
Would it not be more logical to have caravan air con under the double bed, thereby having the weight low down, avoiding the need for a heavier roof and have it in the space where it is most needed.
Additional weight is rarely wanted or needed in a caravan, most sensible users try to keep touring caravans as light as possible. However if an AC is fitted, it causes less weight related stability problems if its on the floor rather than roof level.
You are correct about optimal operational location being high up rather than low down. Roof mounted units don.t usually need extra ducting to distribute the cooled air. Also they can get away with lower pressure fans and might be quieter, where as floor mounted ones do need ducting, so not only the additional weight but the ducting also needs to have space allowed, and it isn't always easy to route it ideally. You need a higher pressure fawn to blow teh air along ducts so its likely to be noisier.
There are many detail differences between cars and caravans which will affect the ultimate performance, but essentially cars will always have more mechanical power available to drive the AC compared to the power available in a caravan. yet cars have a much smaller habitation volume so the system most people are now used to is far more powerful than any system that can be fitted to a touring caravan, yet the caravan has a far bigger volume, and indeed surface area to collect solar heat energy, so the AC has mighty task on its hands. These are some of the reasons that caravanners who have AC fitted may have great expectations but the reality is often disappointing. Most will says its not a total waste but it will never have the same impact as AC in cars.
Hutch has mentioned water evaporative coolers. There basically raise the humidity of the air in the caravan. They work well initially, but as time goes by the air becomes saturated and cant take up any more evaporated moisture. so they become less effective the longer they are used. Also the water vapour tends to be absorbed by soft furnishings and wood so if you have a cooler night you are more likely to get extensive condensation the following morning. The raised humidity with temperature is also a better breeding ground for microbes. I have seen what they can do to someone with lung problems.