Go Back   iRV2 Forums > iRV2.com COMMUNITY FORUMS > iRV2.com General Discussion
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 06-30-2016, 05:58 PM   #1
Senior Member
 
Join Date: Oct 2015
Location: Albuquerque, NM
Posts: 421
Air Flow Direction for Roof Vent

I have a fairly unimportant question.

It's currently 74 outside and 90 inside. I have the windows open and the fan in the roof vent going. I can't decide if I should be

moving the hot inside air to the outside or
blowing the cooler outside air inside or
if it doesn't really make any difference.

I'm leaning towards the third. What do you think?
__________________

__________________
alvo is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 06-30-2016, 06:03 PM   #2
Senior Member
 
Mr_D's Avatar
 
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 28,452
According to support at Fantastic Vent the air should be drawn in from the openings on the shaded side and exhausted out the roof vent. I asked them that question some years ago.
__________________

__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
Mr_D is online now   Reply With Quote
Old 06-30-2016, 07:13 PM   #3
Senior Member
 
MtnTrek's Avatar
 
Join Date: Jul 2015
Location: Currently; SW Cali. Sunny & warm!
Posts: 1,114
lotta variables

OK, I have to much time to kill:

Depending on the actual CFM moved by the fan(s), since they're all different #3 might be the actual answer.

Determining shade or sun results may vary.
Allowing for natural convection warm air rises with cool air tending to fall, causing stratification in a closed space. In theory you're correct 74Deg. should able to help lower the coach temp from 90Deg. But is it a puff in a windstorm?
If the sun is shining on the roof of your coach? Lean toward exhausting there.
Which side of the coach (windows) is the sun shining on?
Is there a breeze outside, if so from which direction? This could negate or amplify any effect.
Don't forget the hatch(s) or cover(s) up there can create either a scoop or a venturi effect. The optimal situation would be to draw in the most cool air, and exhaust the warmest, utilizing nature and your orientation to overcome the solar gain.
This being said it's not difficult to overwhelm some of these ventilators. Any time of day or situation might be different.

Wet finger in the air, yeup, mine are open, fans are off at the moment and 71 OS, 73 IS, afternoon sun on the nose cap. Yeah baby, smells like money in the bank!


Yeah, What Mr D said. lol

Happy motoring.
__________________
DRV Suites, ES-38RSSA
J & J & Kickr's the Vonderhund
GM Denali, 3500HD-Max, CC, 8'-DRW, 4x4
MtnTrek is offline   Reply With Quote
Old 06-30-2016, 07:30 PM   #4
Senior Member
 
Mr_D's Avatar
 
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 28,452
So, bring a wet bulb thermometer with you!
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
Mr_D is online now   Reply With Quote
Old 06-30-2016, 11:13 PM   #5
Senior Member
 
MtnTrek's Avatar
 
Join Date: Jul 2015
Location: Currently; SW Cali. Sunny & warm!
Posts: 1,114
Darn, I gave away that sling psychrometer and slipstick (slide rule) at a garage sale many yrs. ago.
__________________
DRV Suites, ES-38RSSA
J & J & Kickr's the Vonderhund
GM Denali, 3500HD-Max, CC, 8'-DRW, 4x4
MtnTrek is offline   Reply With Quote
Old 07-01-2016, 05:59 AM   #6
paz
Senior Member
 
paz's Avatar
 
Join Date: May 2005
Location: Full-timers - Home is where we park it.
Posts: 4,716
We always have our vent fans blowing out for the reasons Mr D gives - air on the roof is hot, and we can bring air into the RV from the shaded side.

Not only that, but if you blow air in, it will be coming from only one place. If it blows out, you can control which areas get more or less ventilation by opening and closing windows in different areas of the RV.
__________________
2015 DRV Tradition 375KPS
2015 Chevy Duramax 3500HD LTZ Dually
Full-timers...Home is where we park it.
Check out our blog: Living Our Dream
paz is offline   Reply With Quote
Old 07-01-2016, 11:03 AM   #7
Moderator Emeritus
 
Gary RVRoamer's Avatar


 
Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,073
We nearly always have the fans in exhaust (blowing out), but once in awhile it's nice to have a direct blast of cool air coming down IF we are actually near the fan.

With several windows open, each one gets only a modest proportion of the air movement, so if you want to feel a breeze coming in, only have one or two open.

The total amount of air moved is the same either way. It just depends on where/how you want that air directed.
__________________

__________________
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Reply

Tags
roof, vent



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Chassis A/C - heater air direction control BarbandBob Workhorse and Chevrolet Chassis Motorhome Forum 6 07-25-2014 01:08 AM
Roof Vent Cover - Fan-tastic Vent vs MaxxAir Turbo TwelveVolt Gear and Product Discussions 4 03-18-2014 03:58 PM
Dometic Brisk Air Direction sixthwheel RV Systems & Appliances 2 10-13-2013 04:52 PM
What is correct direction of air flow on air conditioner Biggee RV Systems & Appliances 10 08-21-2013 08:44 PM
Basement Air Filter direction R. Francis Winnebago Industries Owner's Forum 9 07-06-2012 10:13 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 11:16 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.