Computer Fans on AC Ducts?

[wopachop]

Thanks to member LandYacht ive learned that modern computer fans are super efficient and quite powerful for their size.

My toyhauler AC is ducted. You have the choice whether to open or close the main vent. With the main vent open its really loud inside, but i got to think running through ducts reduces it efficiency.

What about attaching a computer fan to the outside of the vent? Or maybe even pull cover and attach the fan inside the AC unit at the start of the duct. Because again thanks to landyacht it seems the fans do a better job at pushing through a restriction. Could even get a small 12v converter and wire to the 110v feed of the ac unit. Or even better find the wire or terminal that gets energized when the AC unit turns on. So the fan would turn on automatically.

Any thoughts?

[wopachop]

This little 140mm is doing pretty good. Using it to suck hot air from the main room and blow it into the front bedroom where the a/c is running.

Got enough suction to hold a paper towel on the roof vent that normally blows air when the main room a/c unit is running.

The idea is to put hours of run time on the front a/c unit in hopes to cool down the main room where i spend 99% of my time. I dont sleep in the front bedroom unless we go dirt camping. (its a toyhauler)

[pnichols]

sgip2000 wrote:
Do your ducted vents have dampers that can be closed? I swapped all my vents to ones with dampers. Close the ones you don't need open and it'll redirect more air to the ones you need.

This is one of the best ways to get better cooling effects from an existing ducted A/C system.

Ours came that way and we adjust the dampers in the duct outlets all the time depending upon our needs.

(However, we have a Class C MH, so as a bonus we can also idle the engine to run the cab air along with the roof air to bring down the coach interior temps in a hurry.)

[mikefos]

ktmrfs wrote:
the best improvements to my AC in my trailer were:
3) block off the ducting shortly after the last ceiling vent.

How did you do this one? Thanks.

[mchero]

wildtoad wrote:
First thing I’d do is make sure you’re not losing air at the source. In my last mh a good bit of cold air was going back up the return as the divider between the two sides was poorly done.

X2!

[wopachop]

Reverse Flow Through Ducts:

Heres an idea people might like. Possibly adapt to your own setup.

This toyhauler came with an AC unit in the main room. With ducts that feed the bathroom and small front bedroom.

Previous owner added a secondary AC unit to the small front bedroom that does not have any ducting. To keep noise levels down im running the AC unit in the front bedroom and then blowing the air backwards through the ducts to come out in the main cabin.

Its working ok. I dont have the blower on high because im not sure how they construct and seal those ducts. Also the blower is not sealed its just hanging from wires floating there. I do feel cold air hitting me. Only noise is a computer fan up at the Main AC unit and from this chair my sound meter app is saying 47-49db. When set next to the fan its upwards of 70. Dont have a dimmer so that will drastically drop as the fan is getting 13.5v right now.

[YC_1]

Drop your vents and see if they stick up too far thus blocking proper air flow. If so cut them down and line the opening with metal duct tape to smooth out the air flow.

Remove the intake shroud and clean up that area with the tape. Lots of leaks and rough air flow in there.

Make sure the AC condensers are clean. There are plenty of videos on how to do that.

[ScottG]

Deleted

[ktmrfs]

the best improvements to my AC in my trailer were:

1) remove all the ceiling vents and then use metal duct tape, close up any gaps between the vent and ducting then reinstall the ducts
2) drop the main cover around the AC and again, using metal duct tape close up every gap between the AC unit and ducts so ALL the cold air goes down the ducts
3) block off the ducting shortly after the last ceiling vent.
4) following the ducts, I added a total of 4 more ceiling vents in the existing ducting. 2 in the living area, one in the bathroom and one in the bedroom.
5) replaced all the factory ceiling vents with aireoport vents (Amazon). The vents deflect air in a 360 degree circle and can be easily adjusted to increase or decrease airflow through a given duct. a quick twist is all that's needed to open or close them.

Doing the above made a very very noticeable improvement in the AC in the trailer.

[DiskDoctr]

Fans PULL air much better than they push it 😉

If you have room in the ceiling above the grill, why not hook up a fan in there temporarily and see what happens?

Double stick tape the fan to the top of the grill, stick the wires out between the grill and the ceiling and hook to a 12v source.

Now here is the crux....

You have to run it for at least 20-30 mins to evaluate it. Initially it will seem like a MAJOR difference, pulling cool air out of the ducts faster.

...but...your A/C only has a certain cooling capacity. If you move more air through your ducts, there is a point where the A/C cannot effectively cool that volume of air.

The good news? If recirculating the air, you will be feeding cooler air into the A/C as you go, meaning the A/C performance can actually be better than simple...(too much detail and likely others are more knowledgeable about A/C performance curves than I am, so I'll stop there, LOL)

I think the rough and thin ducts in our campers can use all the help they can get for moving air. Should be a good result 😉

[wildtoad]

First thing I’d do is make sure you’re not losing air at the source. In my last mh a good bit of cold air was going back up the return as the divider between the two sides was poorly done.

[TakingThe5th]

Check your ductwork as best you can to see if everything is clear and open. If you do use fans, remember that cold air is harder to push then warm air, so get the larger fans. Muffin fans come in both 110 and 12 volt versions.

[sgip2000]

wopachop wrote:
Thanks to member LandYacht ive learned that modern computer fans are super efficient and quite powerful for their size.

My toyhauler AC is ducted. You have the choice whether to open or close the main vent. With the main vent open its really loud inside, but i got to think running through ducts reduces it efficiency.

What about attaching a computer fan to the outside of the vent? Or maybe even pull cover and attach the fan inside the AC unit at the start of the duct. Because again thanks to landyacht it seems the fans do a better job at pushing through a restriction. Could even get a small 12v converter and wire to the 110v feed of the ac unit. Or even better find the wire or terminal that gets energized when the AC unit turns on. So the fan would turn on automatically.

Any thoughts?

Do your ducted vents have dampers that can be closed? I swapped all my vents to ones with dampers. Close the ones you don't need open and it'll redirect more air to the ones you need.

[sgip2000]

2oldman wrote:
I have several vents. What do you mean 'main vent'?

The ducted systems have a grill like this.

The lever can be slid to one side to let all the cool air dump directly down from the A/C. Slide the lever to the other side and it becomes ducted.

[2oldman]

I have several vents. What do you mean 'main vent'?