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

John_Wayne
Explorer II
Jul 14, 2016
Another thing to check is pull the vent cover at the front and rear of the ducting in the MH. If it's like mine the duct just keeps going into the end caps. I cut a plastic bowl in half installed into the duct at the last vent on each duct. At the vent and filled the space around the bowl with foam. Now any air reaching the last vent at each end of the duct is directed into the MH instead of the end caps.
doxiemom11
Explorer II
Jul 14, 2016
Our rv neighbors purchased a new trailer last year and the 1 AC ran all the time. Living room comfortable but not the bedroom. It was prewired for a 2nd AC in the bedroom so they spent the $ and added one this year. Son did installation. She mentioned the above and when he checked the living room AC the baffles were not opened to allow air to get out of the AC and blow the air out like it should. ( not vented). After correcting that they now wonder if they even needed the 2nd AC ! She had called dealer and mfg several times to no avail, no one ever checked the AC even when they requested it when other work was being done. Check your unit you have first before modifying or adding a 2nd.
Sir_Ken
Explorer
Jul 14, 2016
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 amps

It 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
Stefonius
Explorer
Jul 14, 2016
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.
dtappy3353
Explorer
Jul 14, 2016
Great idea.

Where did you get the fans from?
wildtoad
Explorer II
Jul 14, 2016
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.
jdavidsmi
Explorer
Jul 14, 2016
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?

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Adding booster fans to your ceiling A/C vents.

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