[Shop-talk] "portable" AC units

[Peter Murray]

I have a fair amount of experience with these sorts of units. As has been
mentioned earlier, they're pretty noisy, and not terribly efficient.

Simpler units have just a single output hose and a condensate tank/pump.
Slightly less simple units will send that moisture out via the hot exhaust.

Fundamentally, there are two inputs and two outputs - evaporator in/out,
which absorbs heat from the conditioned space and outputs cool air, and the
compressor in/out, which takes outside (unconditioned space) air and
exhausts the heat from the compressor coil.

Most simpler units combine the compressor and evaporator intake - which
leads to negative air pressure in the conditioned space (because all intake
air comes from the conditioned space), and outside (unconditioned) air
leaks in through any available aperture (or the room approaches a vacuum),
and therein is a big source of inefficiency.

If your office has forced-air ventilation, but just doesn't have enough
airflow, perhaps a duct booster blower like this would help?

https://www.homedepot.com/p/VENTS-US-162-CFM-Dryer-Booster-Fan-with-4-in-Duct-VENTS-VK-100-PS/206398496

Of course, if your office is pretty dry while hot, you could employ some
evaporative cooling.

-Peter

On Tue, Aug 24, 2021 at 2:10 AM Brian Kemp <bk13 at earthlink.net> wrote:

> I bought a single duct portable AC for a bedroom that had a sliding window
> in a house without AC.  The duct is similar to a dryer exhaust and can be
> permanently mounted in the wall like a dryer or bathroom exhaust vent.
> This unit had a 4" duct.
>
> Too loud to use while sleeping.  The single duct exhausted the conditioned
> room air outside like a powerful exhaust fan.
>
> In a network closet at work they installed a better unit with 8" supply
> and return ducts and a condensate pump.  It is even louder to the point
> that you can't have a conversation nearby, but does keep the room at 65
> deg.  This unit is installed with both ducts going to a bracket that mounts
> in the suspended ceiling.  They had to get a plumber to run a drain line
> for the condensate pump.  An electrician also had to install a dedicated
> 20A circuit.
>
> I'd encourage other solutions.  Had problems with no air in my office and
> finally got a facilities guy to take a look.  It turns out they ran some
> big conduit for lots of network cables and the supply duct was in the way,
> so they just disconnected it and the duct was blowing cold air above the
> ceiling.  The guy moved the supply grill to a different ceiling grid
> location and reconnected the duct.  Maybe you can get this lucky.  Most
> offices also have a baffle or damper to balance air flow.  Maybe yours is
> shut because the previous person found it too cold.
>
> I've also seen people take a box fan and use some coat hanger wire to
> attach it to the ceiling return grid to serve as an exhaust fan, removing
> hot air from the office.
>
> Brian
>
> On 8/22/2021 4:23 PM, Tim . wrote:
>
> Does anyone here have any experience with said appliance?
>
> My main wonder is where does the exhaust go? Does these things have an
> exhaust "port" that I can hook a hose up to and run it where ever?
>
> thanks
>
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