Location of second fan: floor or roof?

joeDiHare

New member
I installed a fantastic fan on the rear part of the roof.

Since the Sprinter (T1N) doesn't have windows, a second vent (more like a whole with a net) is necessary for wind flow.

Would you recommend a floor or roof vent?

The ceiling seems more common, but think about it, a floor vent
- doesn't have rain-leak issues
- sunlight leaks
- it's pulling in (possibly) cooler air
- it should provide more flow with the other vent being on the ceiling
- and it doesn't take space from, say, solar panels.

I wonder if I am missing some cons?
 

john61ct

New member
Need to seal while the engine is running, or at least while driving, depending on location.

And critter screening.

Marine deck plates work well.
 

Onefin

Well-known member
I installed a fantastic fan on the rear part of the roof.

Since the Sprinter (T1N) doesn't have windows, a second vent (more like a whole with a net) is necessary for wind flow.

Would you recommend a floor or roof vent?

The ceiling seems more common, but think about it, a floor vent
- doesn't have rain-leak issues
- sunlight leaks
- it's pulling in (possibly) cooler air
- it should provide more flow with the other vent being on the ceiling
- and it doesn't take space from, say, solar panels.

I wonder if I am missing some cons?
Floor vent works. Graphite Dave has long been a proponent of them.
https://sprinter-source.com/forum/showthread.php?t=38276
 
I have two 2x10 floor vents and no other opening windows. Works very well with roof fan and you can feel the cool air coming in from underneath. Have a typical floor register in place and a small rug to cover them when not in use. I would recommend floor vents as easy way to improve airflow when used with a roof fan.
 

brucedog

Member
We have two roof vents and love them. When we sleep we close all windows, set forward fan to exhaust which pulls cold air quietly right onto our faces through the rear fan. Think about it...is the night air really that much colder ten feet lower? Just my opinion ��
 

OrioN

2008 2500 170" EXT
We have two roof vents and love them. When we sleep we close all windows, set forward fan to exhaust which pulls cold air quietly right onto our faces through the rear fan. Think about it...is the night air really that much colder ten feet lower? Just my opinion ��
I thought about it......


....not biting, one fan and one floor vent is still better than two roof fans. Why? No need to run the fan motor to get the inside air as cool as the air outside under the van. :thumbup:
 

elemental

Wherever you go, there you are.
Sounds like both approaches have merits and drawbacks. It is good that we all can make our vans as we want, rather than be forced to a single plan from a single vendor. I myself am planning on two roof vents with fans on a 170" wheelbase van, although I seem to be taking my own sweet time cutting the second.

I've thought about the floor vent/ceiling vent combination as several have recommended it from actual experience. I have decided to stay away from any openings in the floor of the van so as to keep the elements at bay while driving in inclement weather, especially with winter roads treated against icing. Potential carbon monoxide intake to the living space should the exhaust spring a leak also was a risk I thought to avoid, although it would only be a problem if the engine were running. I have managed enough roof real estate on a 170" wheelbase van to have two fans, one forward, one aft, with 4 solar panels in between; this also provides simultaneous intake and exhaust so as to achieve a gentle flow through. On a 144" wheelbase the roof real estate would be more precious, and the floor vent's benefits would take on more allure for me, I think.
 

OrioN

2008 2500 170" EXT
Sounds like both approaches have merits and drawbacks. It is good that we all can make our vans as we want, rather than be forced to a single plan from a single vendor. I myself am planning on two roof vents with fans on a 170" wheelbase van, although I seem to be taking my own sweet time cutting the second.

I've thought about the floor vent/ceiling vent combination as several have recommended it from actual experience. I have decided to stay away from any openings in the floor of the van so as to keep the elements at bay while driving in inclement weather, especially with winter roads treated against icing. Potential carbon monoxide intake to the living space should the exhaust spring a leak also was a risk I thought to avoid, although it would only be a problem if the engine were running. I have managed enough roof real estate on a 170" wheelbase van to have two fans, one forward, one aft, with 4 solar panels in between; this also provides simultaneous intake and exhaust so as to achieve a gentle flow through. On a 144" wheelbase the roof real estate would be more precious, and the floor vent's benefits would take on more allure for me, I think.
Close the vent while driving.
 

autostaretx

Erratic Member
Close the vent while driving.
Requires memory at times when such may be lacking. (*)

--dick (hmmm... :hmmm: motorized floor vent closure powered by EK1 "ignition on" terminal?)

(*) i'd say "been there, done that", but it's more a case of "permanently there"
 

elemental

Wherever you go, there you are.
Requires memory at times when such may be lacking. (*)

--dick (hmmm... :hmmm: motorized floor vent closure powered by EK1 "ignition on" terminal?)

(*) i'd say "been there, done that", but it's more a case of "permanently there"
I too like designs that depend as little as possible on the operator's memory/knowledge.

From a fail-safe perspective it might be better to have a spring-loaded floor vent closure that required power to counteract the spring and open the vent, with EK1 ignition on turning that power off through a relay. Like the electro-magnet "hold open" devices for fire doors. Done carefully the current load for hold-open could be fairly low. But then... the function would be so automatic the operator might never double-check it, and a failure then would be unlikely to be noticed until too late. Now we'll have to have a "red light/green light" board like on a submarine to make sure all system are safe for d(r)ive...
 
Think about it...is the night air really that much colder ten feet lower? Just my opinion ��
I got myself one of those infrared temperature gauges recently. My Sprinter is black and quite well insulated, with only a wind powered Flettner vent at the back.

On a day with an outside temperature of 75F, with sunshine and blue skies, the top portion of the van is easily 95F or hotter.

The interesting thing is, the air at floor level (without any floor vents at the moment) is about 75F to 78F and increases in temperature higher up. The hot air flows to escape naturally by convection through the Flettner vent. The cooler air heats up as it rises of course and the cycle continues. I have my front windows open slightly.

So the air at floor level is easily 15F-20F cooler than the air near the ceiling. I imagine having a couple 2x10 vents in the floor would definitely bring in the cooler air under the van. At night time the temperature difference wouldn't be that much, but during the day it's quite significant.

Hein's door prop already makes a big difference for additional airflow through the van when parked. It also works very well at highway speeds (had the rear door unintentionally propped open with the device the other day).


For those who have the floor vents, are there any preferred locations?
 
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GSWatson

2013 144
I’ve seen a couple of vans where the vent is in the short step wall of the sliding door area; that seems like as good a place as any.


Cheers,
Greg
 
I’ve seen a couple of vans where the vent is in the short step wall of the sliding door area; that seems like as good a place
Greg, thanks for this.

Are there any "how to" instructions or videos on how the step area can be modified?

Mid-ship on the floor would be fairly straightforward. But the step area has the slider, plastic step and then the metal below.
 

OrioN

2008 2500 170" EXT
Greg, thanks for this.

Are there any "how to" instructions or videos on how the step area can be modified?

Mid-ship on the floor would be fairly straightforward. But the step area has the slider, plastic step and then the metal below.
I started the trend.... the vents listed below fit perfectly on the facia/kick face. :thumbup:


I don't have a picture as it is now covered with an up-fit.
 

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