Dear Dave,
We are planning to replace the air conditioner on our class B Sprinter Leisure Travel van. My question is: To what extent will an RV air conditioner help to filter out wildfire smoke? It seems to me that the air conditioner would need to be able to have a recirculation mode and a fresh air intake mode. Is there a clear choice out there for one that does a better job than others in keeping the interior relatively smoke-free? Thank you so much for your help with this. —Leslie
Dear Leslie,
Thanks for the question, as this is a fairly big issue these days with all the wildfires around North America.
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How an air conditioner works
Your rooftop air conditioner will do a slight amount of filtering depending on the type of unit you have. Most rigs come with either Dometic or Coleman units. Lower price models have the vent and fan directly at the air conditioner and others have ducted vents in the ceiling. Both have an interior air return that draws warm moist air from the upper portion of the rig into the unit and through the evaporator fins. This air return has a filter in both the direct air and ducted type of models.
As you can see from the photo, the filter is a very thin piece of cell foam and designed more for keeping out dust and pet hair than actually filtering smells. Some of the ducted roof air conditioner models have a little better filter. However, it’s nothing like a residential filter you would see in a furnace/air conditioner model, and nowhere near a HEPA-type filter. You don’t want to replace the flimsy filter with something heavier as it will reduce airflow to the unit and eventually cause the motor and compressor to fail.
So what should you do?
I would suggest getting an air purifier that you can put anywhere in your rig. They are very compact and don’t draw many amps, so you should be able to run the roof air conditioner and the purifier at the same time. I would recommend going with a unit that utilizes charcoal. These models seem to have the best reviews but do cost a little more money. The unit I have is a Honeywell that I got at an auction a thousand years ago and it works great. It’s just a little heavy and draws about 8 amps, so I have to do some energy management. One that seems to be very popular is this one made by Blueair.
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How can my RV’s roof air conditioner run more efficiently?
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I’d like to improve the efficiency of our roof air conditioner. The factory shrouds are black. I’d like to paint them white. Second, I’d like to insulate the pipe from the compressor to the evaporator. Thanks. —Joe, 2019 Coachmen Pursuit
Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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Thanks, Dave!
I followed your link and watched a video. Looks like if I get one of these units I will immediately start exercising and getting into shape. Stay tuned . . .
I think the OP is concerned the air is coming in from the outside when the AC is running. The design of the system does not draw outside air through the evaporator into the interior, but only recirculates the inside air. As long as no windows or the door are opened, the outside air remains outside.
With it being a class B it will have in dash A/C system also that if left in the normal position outside air can be drawn into the RV. I would advise having the dash A/C control in the max A/C position which closes off 90% of the outside air. This should reduce the amount of smoke getting into the motor home. Or completely shut off the dash air eliminating out side air intrusion.