Adding booster fans to your ceiling A/C vents.

[Sir Ken]

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.

[sanfordturbo]

what a clever idea.

I'm not sure how much cold air you will draw out of the existing system, but it will certainly move more air around in the cabin.

I went another route to cool down my cabin. I installed a 2nd unit.

[twinboat]

You need to be carefull not to pull too much air thru the coils to fast.

They won't have enough time to extract much heat and you will use effectiveness.

[Sir Ken]

Originally Posted by sanfordturbo

what a clever idea.

I'm not sure how much cold air you will draw out of the existing system, but it will certainly move more air around in the cabin.

I went another route to cool down my cabin. I installed a 2nd unit.

You rich people.

Originally Posted by twinboat

You need to be carefull not to pull too much air thru the coils to fast.

They won't have enough time to extract much heat and you will use effectiveness.

Mostly trying to move more air but I see your point.

[YC1]

I found the vents in mine protruded way up into the duct work. Seems the further down the chain I lost a lot of air. Trimming them down to be level with the inside bottom of the duct improved air flow.

[mel s]

Adding a 4" x 8" register into the air conditioner ceiling cover, (directly below the output), allows you open the register and direct the flow of cooled air downward to cool the area faster...(when the register is closed the cooled air flows normally).

[TQ60]

These are great ideas.

Yes they could cause too much air glow across evaporator but they also compensate for resistance to air flow in the duct work.

An old school non electronic thermostat can be used to control the fans.

[YC1]

Mel, I did something like that too and it worked well. The problem is the fans are so noisy I had to turn the television up and down.

Going inside the intake of the air conditioner with some duct tape I made sure there were as few sharp angles and leaks as possible. I then cut the intake area hole as large as possible and covered the part that would be where you installed that register. Thus eliminating any noisy air output at that location.

The noise dampening cover is a 12 inch by 12 inch filter box with two latches and intake vents. I forced the intake vents closed and lined the inside of them with noise dampening material. Opening the end away from the main area of the rv allows plenty of intake air and really keeps the fan noise down to half or less.

[mel s]

Originally Posted by YC1

Mel, I did something like that too and it worked well. The problem is the fans are so noisy I had to turn the television up and down.

Going inside the intake of the air conditioner with some duct tape I made sure there were as few sharp angles and leaks as possible. I then cut the intake area hole as large as possible and covered the part that would be where you installed that register. Thus eliminating any noisy air output at that location.

The noise dampening cover is a 12 inch by 12 inch filter box with two latches and intake vents. I forced the intake vents closed and lined the inside of them with noise dampening material. Opening the end away from the main area of the rv allows plenty of intake air and really keeps the fan noise down to half or less.

YC1

Great minds think alike.
(Sometimes you have to "think out of the box").

[YC1]

The pop down duct worked well but starved other areas of the rv. Quicker cooling at first but when closed there was additional noise from air still passing through.

When I began the project I could just barely feel the air out of the furthest vents. Now I can get chilled under them.