There are several ways to keep your RV cool or ventilated. The cheapest way is with the standard crank open roof vents. Most RVs today are built with a 14″ x 14″ crank open vent in the roof. A better way to ventilate your RV. Would be a powered roof vent. As seen in many RV bathrooms. These can be installed anywhere in the RV. There are companies out there that make large powered fans that go in the standard roof vent opening. These fans can move a lot of air either in or out of your RV. Some of these fans can be controlled by a thermostat To turn the fan on when it gets hot inside. These powered roof vents are often powered by your RVs battery. There are also solar powered vents and vent covers. These allow the RV to be ventilated even in your absence. Also available are vent covers that are designed to allow you to have the vent open even in the rain.
Another way to keep your RV cool would be by your roof air conditioner. These units not only cool but also remove humidity from inside the RV. Most often the a/c units are mounted on the roof. These can be either standard roof air conditioner or central air conditioner. These air conditioning units require 110v power. Either from shore power or a generator. Air conditioners are a freon based appliance. The compressor moves the freon around the system. Cooling the air that moves past the evaporator. This means that it needs to take air in as well as putting cool air out. The air it takes in is called return air.
There are two styles of roof air conditioners. One is direct venting. This type has the cool air come right out of the a/c unit into the RV. The second style is ducted (sometimes called central air conditioning). This style takes the cool air and pushes it through duct work in the ceiling of the RV. Ducted roof air allows the cool air to be delivered directly to each area of the RV. Don’t forget that if you are cooling a room. You should open the privacy door to allow the return air out. Direct vent a/c have all the controls on the inside shroud. Most ducted a/c units use wall mounted thermostats to control them. There is some care that needs to be done to a/c units. 1st being cleaning the filters on the return air system. The second would be to get up on the roof and look at the back of the a/c unit. The fins need to be kept undamaged. Some times tree branches will rub against them and bend them. If you are very careful you can straighten them out. Normally you do not have to recharge they don’t often loose freon. If you are going to cover your a/c unit in the winter. Remember that squirrels and animals like to live in there till spring and may eat parts of your rv.
The size of your RV will dictate the size of a/c unit you need. A 7100 BTU unit is good for pop ups. The 7100 air conditioners are lighter in weight as to limit the extra wear on lifter system. 11000 Btu units are good for smaller travel trailers. 13500 Btu is the average size. Most manufacturers use this size on their RVs. These are good dependable units and they put out a lot of cool air. If your RV is over 30′ you may want to consider a 15000btu air conditioner or look at putting a 2nd a/c unit. The only problem with installing a second a/c unit is if you only have 30 amp electrical service. You can only use one unit at a time. If you have 50 amp service you may be able to use both together. Many manufacturers are switching to a 15,000btu a/c ducted to the entire unit. There are some options available for roof a/c units. 1st being a heat strip. These can be installed in the a/c at any time. What a heat strip does is heats the air coming out of the vents when it is set for low fan operation. These will not heat an RV however they will help to take the chill out of the air on a rainy day.
Some new a/c’s are available with a heat pump built into them. So they work more like a home air conditioning unit. These basically run backwards. Remove cold air and put in warm air. Roof air conditioning units weigh between 85 and 120 lbs. depending on the size you want.