The Most Efficient / Quiet way to Cool Off any Camper
The first priority project has been completed! Since we’re installing in a custom camper this is not a how to install but rather a review of the benefits which are huge and why it makes sense to not choose a standard RV AC unit. Definitely made sense for us and if you’re renovating it’d be a worthy considering for any RV.
What’s Next?
After the A/C task, there’s remains about 2 weeks left of project time before we go wheels up. Summer 2021 Traveling starting soon. It’s heating up around here and it’s already time to move on.
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Wanting to install a mini split in my 32 ‘ class a rv. All the info says a 12k btu 1T. will suffice, it makes me a little nervous since both oem Coleman roof tops equals 27k btu which which is about 2.25 t. A/C please comment on this . I def want to install enough capacity to cool the beast with 2adults & 4 kids
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Several things to consider. First some comments on the design intent for a Class C;
1) Most rooftop A/C units are of low efficiency and are relatively easily and cheaply made larger (which they often are). They are big enough that they should be able to cool the interior when exposed to full sun but also assume that they are on shore power where power consumption is not an issue. Oversizing can be economically done.
2) Since most rooftop A/Cs are of the same size, the larger the RV becomes, the only way to provide conditioning in the interior where it is needed is more about air circulation than A/C capacity. As RV’s are long and there is no air handling equipment that forces circulation of the air from front to back or room to room along the length of the RV. The only/easy solution to cooling two rooms (which is often the case) is to use two separate units, not because the capacity is needed but because air handling becomes a problem.
With these in mind, there are some more specific questions you want to consider;
1) Most RV’s have terrible insulation and poor air tightness which contribute to a need for greater A/C capacity. You should evaluate your RV’s relative capacity in this respect. If you have better than average insulation (>=1.5″ wall thickness) and double-pane windows, you are ahead of the pack.
2) With #1 in mind, what temperatures are you likely to be experiencing that will require A/C? Since I am mobile and don’t think I want to ‘stay around’ in temperatures over 100F, I don’t need to be concerned with enough A/C capacity to tolerate more than that. I routinely will seek a higher elevation in an area I am visiting if the daytime ambient temperature gets too high or leave altogether. After all, I have a mobile residence for a reason.
3) Building on #1, will your RV be completely exposed to harsh sunlight in which heat loading from the sun will be very high or are you likely to be able to be in the shade? This is a big factor in how much A/C capacity you may need. Orienting your RV east-west with an awning on the south side can substantially reduce heat gain. If you imagine camping in an RV park with shore power access, this is likely not an option you can plan on but there might be trees (?).
4) Probably the biggest issue will be air circulation more than capacity. It can be an enemy or a friend but going from 2 roof units to one IDU will make it worse. If you don’t use/need cooling in a back bedroom during the heat of the day, lack of air circulation is not a big issue, but it will be a challenge to cool it off before bedtime. IF you NEED (which is what i feel you are intending) to condition the entire space, you most likely will need more equipment to do so. ‘Mini- split’ is a term where 1 outdoor unit (ODU) operates 1 indoor unit (IDU). Graduating to a ‘multi-split’ is using 2 IDU’s (to replace the 2 roof units) that operate off of a single ODU, (probably requires a 1.5T ODU). This is likely where you should look if you expect interior airflow issues (likely). The immediate problem this causes is that 3/4T and 1T units are available in 120V but 1.5T and above are all 240V units. If your RV is 120V/30A, this becomes a problem as it will require a modification to 50A/240V which would be $$$. I solve the airflow problem in my camper using a 2″ high ‘false ceiling’ with 2 air ducts in it to force a front to back air circulation. The IDU is at the back of the RV and would never cool the bunk. With the ducts and 2 ‘high static pressure’ 140mm fans, I pull air through 14′ of 2×5 ducts and deliver it right into the top of the IDU. This helps cool the bunk but there is still a temperature difference between rooms (which also works to heat it). I could see you doing something similar but don’t imagine it would be easy.
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