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Old 07-12-2019, 05:23 PM
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Which way should I direct a fan while the A/C is busted?


Hey, everyone.

The A/C in my second story is out of commission. Most of the second story is down a single hallway, separate from the main floor. While we wait in the queue for repair, I have a giant fan to circulate air. Should I place the fan to blow cooler air from the main floor down the hallway toward the rooms on the second floor, or should I place the fan to blow the hot air away from the rooms and toward the main floor?

(Mods, if this is more of an IMHO post, feel free to move it, but I thought a factual "air circulation" answer may exist.)
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Old 07-12-2019, 05:37 PM
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this article has a lot of good info on fan placement and use

It says at night you want to blow the cooler air from the outside in.

https://www.wikihow.com/Use-Window-F...r-Home-Cooling
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Old 07-12-2019, 06:09 PM
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I'm not quite understanding how the 2nd floor is down a hallway from the main floor. Are there stairs in the hallway?

I had this happen to me. My 2nd floor AC went out, so I blew the cool air from downstairs to upstairs. I also ran the 2nd floor air handler fan to circulate the air around the 2nd floor rooms as much as possible (just my compressor was out). But you will likely need to have some sort of flexible duct to get the cool air from downstairs to upstairs. If you just point a fan towards upstairs, it won't have enough force to actually blow the air all the way to the 2nd story. It's kind of like if you spray a hose into a pool of water. The water stream gets stopped by the existing water and doesn't go very far. It's the same with the air. Cool air from the fan will be blocked by the air that's already in the room. In any case, it's not going to make upstairs feel like it's cool like normal.

What kind of big fan do you have? It will have to be a fan which has a very powerful and directed air stream in order to have enough force to push enough air to make a difference. Something like a box fan or patio fan won't really push enough air through the duct.

Another option is to get a portable AC unit. They have standalone ones that cost about $300. They might be able to keep a room or two cool.

Or have everyone camp out on the 1st floor until the 2nd floor is fixed.
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Old 07-12-2019, 06:10 PM
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It's probably easiest to just have people sleep on the 1st floor until the AC upstairs is fixed.
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Old 07-12-2019, 06:17 PM
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Originally Posted by Bijou Drains View Post
It's probably easiest to just have people sleep on the 1st floor until the AC upstairs is fixed.
It depends ob how nasty hot and humid your climate is right now but that would be my choice.

Your other realistic option is to shut down the ground floor AC, open up every window wide and try to get as much fresh air flowing in and out of your house as possible.
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Old 07-12-2019, 06:58 PM
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Put the fan in the window of the second floor room you want to cool, and blow air from the room outside. Negative pressure in the room will draw in cooler air from downstairs into the room. Of course, air from outside will infiltrate inside to make up the air you are blowing out, making the AC work harder so this is not the most efficient way to operate the AC, but it will work as a temporary measure.

Wait, I am assuming that there is an AC for the first floor. Is that right?

Last edited by Dag Otto; 07-12-2019 at 07:01 PM.
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Old 07-12-2019, 09:35 PM
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Your other realistic option is to shut down the ground floor AC, open up every window wide and try to get as much fresh air flowing in and out of your house as possible.
Do that at night only. As soon as it's warmer out than in in the morning, close all the windows and all available curtains and shades.

If the house has decent air flow and insulation, and the night temperature went down to the low 60's F or below, that should keep the house comfortable or at least bearable all day; come evening, open everything up again as soon as it's cooler outside than in. Open upstairs windows from the top down if possible and relevant, downstairs ones at the bottom (depends on the style of window whether this makes sense or is even possible.)

If the night temperatures are high 60's F or above, this technique doesn't work. But it works very nicely if the nights are cool enough (well, at least if the house is designed for it, with windows on all sides.) ETA: You have to be willing for the house to be chilly first thing in the morning. Dig out a nice warm winter shirt to start off with.

Last edited by thorny locust; 07-12-2019 at 09:37 PM.
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Old 07-12-2019, 11:29 PM
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Wait, I am assuming that there is an AC for the first floor. Is that right?
Yep, fully functioning A/C on main floor, but it just can't keep up in order to cool both the main floor and the upstairs. When I came home from work today, the upstairs was 94 degrees! Outside temps have been 95+ degrees this week with horrible humidity. We've opened the windows upstairs and set the fan blowing out, which seems to have helped "a little."

Additionally, something weird I noticed was that even though the upstairs "system" was turned off, the system fan/air handler was still running, and, as a result, was blowing into the house hot air that had been heated by the very hot attic. I finally had to turn off a breaker to get the air handler to power off. Ugh.

Obviously, no one is sleeping up there until the system is repaired (hopefully soon). And thankfully it is relatively cool on the main floor given the circumstances, but this is not the way I'd suggest bringing the family together.

Thanks, everyone, for your replies. I appreciate the advice!
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Old 07-13-2019, 01:47 AM
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We've opened the windows upstairs and set the fan blowing out, which seems to have helped "a little."
No, don't open the windows, open only one window on the second floor, and only as much as needed to fit the fan in there. If you have more than that window open on the second floor, then the fan won't draw air from the cooler downstairs, it will draw in hot air from outside through the additional open window on the second floor.

Last edited by Dag Otto; 07-13-2019 at 01:48 AM.
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Old 07-13-2019, 06:21 AM
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To me, the main thing for keeping cool is just to make sure there's a fan on you. I can even get it to where I don't sweat when in bed at 90 degrees. Blowing from one room to another has never worked well for me, but I've never tried putting the box fan in the window blowing outward, so I may try that.
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Old 07-13-2019, 07:45 AM
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most AC repairs are done in a day or 2 Why do you have a long wait? Is it hard to get parts or are they putting in a whole new unit?
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Old 07-13-2019, 08:20 AM
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most AC repairs are done in a day or 2 Why do you have a long wait? Is it hard to get parts or are they putting in a whole new unit?
Could well be he's waiting for an open slot on the service tech's schedule. The ones around here are busting their butts trying to get everyone covered. It's the busy time of years for AC repairs.
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Old 07-13-2019, 09:11 AM
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Hey, everyone.

The A/C in my second story is out of commission.
Many times it’s just a blown capacitor. Have you checked if the fan outside on your unit is spinning ?

Before positioning fans and stuff, I’d start there. You can buy an AC capacitor for less than 50 bucks usually.
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Old 07-22-2019, 05:46 PM
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Hey, everyone, sorry for the delay in posting. Here's a brief update:

Repair Guy came out to investigate and found a couple of things:
  1. The main floor system, although working, was low on refrigerant (which obviously means there is some sort of a slow leak); 4lbs added. Now it's super cool downstairs.
  2. The upstairs system will have to be replaced. We have a Lennox system. Apparently the copper coils in this unit were known to be faulty, and there has even been a class-action lawsuit, etc., as a result of the so-called known faulty coil.
    Usually, we'd have two options:
    1. replace the faulty copper coils with new aluminum coils
    2. replace the system.
    Well, our model happens to be one of the models where simply replacing coils is not an option because of the configuration of the design. So, we really only have one option: b) replace the system.

As a result, we've had several different companies come out to provide quotes and "opinions" in order to try to be as educated as possible. We think we've settled on one, but haven't yet made a final decision.

New systems (and duct work redesign) is expensive, y'all.
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Old 07-22-2019, 05:53 PM
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.....New systems (and duct work redesign) is expensive, y'all.
Recommend calling Lennox directly and talking to them. Things maybe under warranty or recall and you wouldn’t know unless you call them.
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Old 07-22-2019, 11:18 PM
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New systems (and duct work redesign) is expensive, y'all.
"duct work redesign" - I can see a little sheet metal work to get the new unit to mate with the existing duct system but it shouldn't be anything dramatic. How much duct work are you expecting to do? What is the explanation for why it's required?
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Old 07-23-2019, 12:49 PM
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Originally Posted by thorny locust View Post
If the house has decent air flow and insulation, and the night temperature went down to the low 60's F or below, that should keep the house comfortable or at least bearable all day; come evening, open everything up again as soon as it's cooler outside than in. Open upstairs windows from the top down if possible and relevant, downstairs ones at the bottom (depends on the style of window whether this makes sense or is even possible.)
While I can do that, I never would as only the bottom half of the window has a screen to keep bugs out & I have never seen windows with top half screens; do they make them? Are they common? I've never seen them in this part of the country so maybe it's a regional thing???
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Old 07-23-2019, 01:52 PM
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While I can do that, I never would as only the bottom half of the window has a screen to keep bugs out & I have never seen windows with top half screens; do they make them? Are they common? I've never seen them in this part of the country so maybe it's a regional thing???
Most of my windows are original to my 1947 home. They're standard, double hung models that use a separate, removable screen that goes over the entire window. Opening the top or bottom of the window makes no difference as far as the screen goes.
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Old 07-23-2019, 05:09 PM
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Spidey I think it depends on the windows. My Orygun house has screens that cover the whole window, but the house I'm sitting in now has screens over the opening only. The Orygun house is about 15 years old.
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Old 07-24-2019, 09:24 AM
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While I can do that, I never would as only the bottom half of the window has a screen to keep bugs out & I have never seen windows with top half screens; do they make them? Are they common? I've never seen them in this part of the country so maybe it's a regional thing???
Most older houses I've seen in this area take, or used to take, separate screen and storm windows, each of which covers the entire window opening, and which need to be switched out in the fall and the spring.

Most newer windows solve the switching-out problem by including integral screens and either integral storm panels or multipane glass or both. This creates the different problem that, if the storm panels remain in the window, at least half of the window is always blocked to airflow.

If they're genuine double-hung windows and not just made to look as if they are, it may be possible to move the storm and screen panels around in some of the upstairs windows so that the screened opening is in the upper half. But the windows may not be designed for this -- modern windows are often designed under the twin presumptions that both air conditioning and electric light are available, and are therefore often not as good sources of either light or air flow as the windows in many old houses (presuming, of course, that we're not way back to when glass was extremely expensive or unavailable.)

(Sometimes also with old windows the window frames have had multiple coats of paint since anyone last opened the upper half, and the upper window won't budge unless all that paint is cut through and the excess removed. It may be necessary to take the window apart to do the job right. But this doesn't sound like an issue that you're dealing with.)
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Old 07-24-2019, 09:31 AM
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Before I got central air in my house, I would put a large fan in the window facing east towards Lake Michigan and suck the air into the house and, on the opposite end of the hall, I had a fan in the window blowing air out. That created a current that kept the upstairs comfortable except on super hot days. I read somewhere that, when the temperature reaches 95 degrees, fans are pretty much ineffective in terms of cooling.
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Last edited by Jasmine; 07-24-2019 at 09:31 AM.
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