I removed one of my ceiling vent covers and measured the opening in the ceiling. I would like to say the hole is perfectly round but it isn't. Roughly 5 inches in diameter.Here is what I started with, 127mm diameter, 38mm deep, 110V, 24W, .22A, aluminum cased, 16MPH, 123CFM, cooling fan.Shaved off the ears of one side of the fan with a combination of hacksaw and dremel tool with a cut-off wheel. Followed up with a table top grinder to remove all of the flat sides of the fan to make it match the circular portion of the fan shroud. I left the opposite side of the fan as-is so that I would have a mounting flange with screw holes. Take care of the small wires and connector while you are at it.I temporarily installed the fan with temp wiring to see what my numbers would be. The vent started at 3.5 mph with the factory installed vent cover. With the booster fan turned on, it went up to 15.3 mph. Granted, the fan is rated for that mph, so that number shouldn't be a surprise however; it sure moves a lot more air now and would hopefully improve the initial cooling time.The fan depth of 38mm is almost exactly the depth of the first layer of Styrofoam in my ceiling. There now is no way to direct the direction the air is blowing but I think I will only put these fans outside the four corners of the main a/c unit. Hopefully this will decrease the time it takes my a/c to cool down the living room area of the rv on those hot summer days. I will be running the wiring through the duct work back to the a/c unit and installing a single on/off switch on the a/c cover to activate the booster fans.

I like this idea, while in MO last month our single AC had a hard time cooling the bedroom. Of course we were in the direct sun no shade anywhere.Is the fan 12 volt? also is it the type that would work with a multi speed switch?

One thing you may also want to check is the AC unit itself to make sure that air is going into the duct system and not back up the return duct. In my last mh I found a lot of air was doing just that, was also leaking out the edges of the cover, and that the input points on the ducting were not cut to proper size.

Great idea.Where did you get the fans from?

Cool idea! X2 on what wildtoad said. I spend about two hours with a giant roll of aluminum tape sealing up leaky and poorly installed ductwork. It made a HUGE difference in air flow. For starters, the separation between the return and output air plenums in the main A/C unit was quite porous. Nobody had bothered to tape up the edges of the styrofoam baffles, and most of my cold air was being sucked right back into the intake.

jdavidsmi wrote:I like this idea, while in MO last month our single AC had a hard time cooling the bedroom. Of course we were in the direct sun no shade anywhere.Is the fan 12 volt? also is it the type that would work with a multi speed switch?110 volts, 24 watts, .22 ampsIt would depend on what company you buy from and what they offer. I know this company offered a 6 foot lead with a built in on/off switch.dtappy3353 wrote:Great idea.Where did you get the fans from?Ebay, just plug in what parameters of the fan you're looking for.wildtoad wrote:One thing you may also want to check is the AC unit itself to make sure that air is going into the duct system and not back up the return duct. In my last mh I found a lot of air was doing just that, was also leaking out the edges of the cover, and that the input points on the ducting were not cut to proper size.Stefonius wrote:Cool idea! X2 on what wildtoad said. I spend about two hours with a giant roll of aluminum tape sealing up leaky and poorly installed ductwork. It made a HUGE difference in air flow. For starters, the separation between the return and output air plenums in the main A/C unit was quite porous. Nobody had bothered to tape up the edges of the styrofoam baffles, and most of my cold air was being sucked right back into the intake.Covered that yesterday in this thread I posted.https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28955299.cfm

Adding booster fans to your ceiling A/C vents. | Good Sam Community

Old-Biscuit
Explorer III
Jul 15, 2016
Sir Ken wrote:
Chris Bryant wrote:

No, worst case it pulls air in from all of the gaps you cannot see or seal in the ductwork.

Perfect, even more air flow.:C

But less overall cooling........
TNGW1500SE
Explorer
Jul 14, 2016
Triker33 wrote:
With Coleman AC you can just put a Chill Grill on. No need to cut holes in the ceiling.

That's what I had in my last TT. It was great. My new RV doesn't have that and it's a coleman unit. Can I just swap it out?
Sir_Ken
Explorer
Jul 14, 2016
Triker33 wrote:
With Coleman AC you can just put a Chill Grill on. No need to cut holes in the ceiling.

I hope no one is cutting holes in their ceiling. I'm using the holes already there without alteration. I can put it all back to factory with a few screws.
Triker33
Explorer
Jul 14, 2016
With Coleman AC you can just put a Chill Grill on. No need to cut holes in the ceiling.
Sir_Ken
Explorer
Jul 14, 2016
Chris Bryant wrote:

No, worst case it pulls air in from all of the gaps you cannot see or seal in the ductwork.

Perfect, even more air flow.:C
Chris_Bryant
Explorer II
Jul 14, 2016
Sir Ken wrote:
Chris Bryant wrote:
With one or 2 of these, you will virtually eliminate the flow from the other vents- In effect, you are robbing Peter to pay Paul.

More than likely it will offset the 1/2 gap between my squirrel cage and the baffle in front of it. Worst case, it pulls more air through the cooling coils with the remaining vents being closed.

No, worst case it pulls air in from all of the gaps you cannot see or seal in the ductwork.
Sir_Ken
Explorer
Jul 14, 2016
Chris Bryant wrote:
With one or 2 of these, you will virtually eliminate the flow from the other vents- In effect, you are robbing Peter to pay Paul.

More than likely it will offset the 1/2 gap between my squirrel cage and the baffle in front of it. Worst case, it pulls more air through the cooling coils with the remaining vents being closed.
Stefonius
Explorer
Jul 14, 2016
Sir Ken wrote:
Covered that yesterday in this thread I posted.

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28955299.cfm
Nice write up! I'll have to add the metal diverter baffles to my own setup.
Chris_Bryant
Explorer II
Jul 14, 2016
Keep in mind, that blower is 123 cfm. The A/C puts out 320 cfm total, so you are pulling over 1/3 of the capacity through that single vent. It will work, though 3 blowers would create a negative pressure in the ductwork, pulling 369 cfm while the air was putting in 320.
With one or 2 of these, you will virtually eliminate the flow from the other vents- In effect, you are robbing Peter to pay Paul.
jjrbus
Explorer
Jul 14, 2016
In many duct designs, the last vent is suppose to be a specified distance from the end in order to function properly!

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