Windowless AC Booster

[OG_TGR]

Hey everyone. I just came across this nice centrifugal fan that I was previously unaware of and thought I'd share.
As anyone who has used these AC units knows, the air that comes out of the exhaust is, by nature, quite hot and also very humid. While most centrifugal fans are technically designed to handle these conditions, they aren't actually supposed to run at the levels that are produced by the windowless AC units, especially if you choose to vent the humidity out of the exhaust as opposed to directly drained off the unit (some give you the option).

http://residential.fantech.net/residential-products/laundry/dryer-booster-fans/

Given that these particular booster fans are made to specifically run in these conditions, as well as the fact that they are marketed for residential applications (as opposed to horticultural) they are not only much more reasonably priced but also perfect for this application.
Most units also come with a pretty short exhaust hose and if you plan on using anything longer, you really need a booster.
Another very nice aspect of this unit is it integrates an airflow sensing switch. This makes it run only when the unit is exhausting, as opposed to running all the time. Previously, I damaged a unit beyond repair by trying to do this with a standard centrifugal fan.

 

[SittingBull]

I use a regular inline fan to exhaust my ac out of the house and always wondered if they made a product like this. My fan is hot to the touch, maybe 85-90f and I have read that the heat won't kill the inline fan quickly however it may wear out the bearings and cause it to wear out faster then normal.

I read the link you posted, including the pdf manuals that are on the website, and couldn't find anything that makes this fan any better then the hydrofarm inline fan that I have!!

Whats the secret???

 

[OG_TGR]

I use a regular inline fan to exhaust my ac out of the house and always wondered if they made a product like this. My fan is hot to the touch, maybe 85-90f and I have read that the heat won't kill the inline fan quickly however it may wear out the bearings and cause it to wear out faster then normal.

I read the link you posted, including the pdf manuals that are on the website, and couldn't find anything that makes this fan any better then the hydrofarm inline fan that I have!!

Whats the secret???

Hey SittingBull.
Well, the category of Inline, centrifugal fans was one that was initially created for an air mover (primarily exhaust) that had a power source that was isolated from the propelling blade/surfaces. This allowed the mechanical aspect of the fan to be exposed to corrosive and/or potentially flammable materials with out the concern of external contamination and/or detonation. I believe that these were then adopted by HVAC applications for residential/commercial and basically anything out of the class 1 (divisions 1-6) environment that they were initially designed for; likely due to the configuration, which was much easier to implement that traditional "squirrel cage" fans which must cause air to change direction by 90°.
So, before the adoption of the design to be implemented in disciplines other than hazardous material handling and/or exposure, the units were all manufactured with very specific materials; relative to the application and class/division exposure. Surely early on it was realized that this wasn't necessary for the majority of general ventilation needs so the resulting commercially available fans would be made of materials that were "good enough". As a result, the fans that your or I would most usually encounter are the standard version of basic steel and likely an outer powder coat for epoxy paint, more for appearance than protection.
Now that I've made a short story long.... this particular unit is

a) manufactured from galvanized steel which is used to accommodate the considerably higher humidity and temperatures associated with dryer exhaust; as well as the mildly corrosive nature of domestic dryer exhaust.

b) manufactured with an integrated flow sensor. This flow sensor allows the fan to only run when there is exhaust pressure present. If the dryer isn't running, neither is the fan. Apparently you haven't encountered this as a problem with your configuration.

Personally, off the top of my head I would attribute this to three possible elements:
1) Your AC unit has been manufactured in such a way that this constant negative pressure isn't an issue.
2) Your unit is susceptible to damage by constant negative pressure but just hasn't been damaged, yet.
3) Your exhaust fan is powerful enough to boost the exhaust sufficiently, but not strong enough to damage the AC unit.
Whether any of these three are true, the addition of a flow sensor could still allow for less time that the fan is running unnecessarily and therefore lessening wear on the fan assembly, as well as consuming less electricity.

And then finally:
c) this particular fan also includes a wired, remote status indicator, telling you when the fan is operating and/or malfunctioning.

Hope this helps.