RV A/C Efficiencies

RV AC units don't need to meet the efficiency standards of home units, and cost is important= low efficiency.

To improve if it is a ducted system, best thing to to do is take down all the ceiling vents, used metal duct tape to seal the gap between the runner and opening and in many cases it easy peasy to add additional duct outlets. usually there are a minimum number of outlets, I easily added two more in our living area one in the bath which had none, and an additional vent in the bedroom.

Made a big improvement. Biggest improvement is sealing all the open gaps in the plenum chamber and also gaps between the AC outlet to the plenum.

Also replace the factory ceiling vents with Aireoport vents

https://www.amazon.com/gp/product/B004P1WTVI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

less restriction than factory vents and more uniform air distribution and easier to adjust.

What causes the ducts to sweat ?

I have heard that adding a soft start system can decrease current draw, but have not seen a cost saving to cost of soft start comparison. Mini split systems use an inverter controlled compressor. Reducing the heat load on a structure will reduce the run time of the ac. Sealing the duct system will improve the efficiency of that. Target cfm across the evaporator is around 400. Reducing cfm to 350 would promote latent heat removal. Increasing cfm to 450 would promote sensible heat removal. Adding a dehumidifier would reduce the latent load on the ac system, thus freeing capacity for sensible heat removal, but there is the cost of the dehumidifier as well as the operating cost to consider. A duct will sweat when the surface temperature of the duct is below the dew point of the air surrounding the duct.

smthbros wrote:
I have heard that adding a soft start system can decrease current draw, but have not seen a cost saving to cost of soft start comparison.

Soft start systems have nothing to do with reducing the kwh consumed.

When you start an electric motor (like the compressor motor), it will draw 2-4 times the wattage but only for a second or so. Once it gets turning, the draw almost immediately tails off.

If you are using a small generator, it may not be able to meet that peak load before going into overload and cutting out. A soft start is intended to reduce that peak load, so a small generator can get the compressor started.

Instead of trying to improve the efficiency of the AC unit, it is much more efficient to to prevent heat infiltration. Things like being sure any air leaks are sealed. Windows are shaded or covered during the heat of the day. Park in the shade. If possible, don’t have the large glass portions of the rig facing west. Limit opening of doors, don’t put extra heat or humidity inside by showering, cooking or doing laundry in the heat of the day.
As for the AC be sure the fins on the unit are clean, all the filters are clean , and if possible, don’t create a cooling deficit by turning the AC way up or off during the day and then try to catch up when you return.

Along with taping the gaps in the vents, take a look at RV Airflow. I did a diy version of the same thing using foam insulation board https://www.youtube.com/watch?v=fBAUuMoD-ec