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-   -   Can portable AC unit intake air from inside room? (http://www.diychatroom.com/f17/can-portable-ac-unit-intake-air-inside-room-50141/)

bludshot 08-02-2009 11:25 PM

Can portable AC unit intake air from inside room?
 
I have a Dual Hose portable AC unit. 1 hose exhausts the hot air and humidity, and the other hose draws in 'fresh air'.

I feel as though the AC unit has been drawing in bad (humid/damp) outside air and making me sick, So I want to just draw the intake air from the room instead. But is that ok to do? Will it harm the AC unit at all or anything like that??

beenthere 08-03-2009 01:24 PM

The intake air is only usedto cool the condenser. It does not come into the room.
If you disconnect that hose. You will have a hard time cooling that room.

Scuba_Dave 08-03-2009 02:06 PM

I have only seen these units with one hose - to exhaust the hot air outside

Yours has 2 hoses?
Where is the fresh air intake hose going?
Are you sure its not a dual exhaust?

bludshot 08-03-2009 02:37 PM

Quote:

Originally Posted by beenthere (Post 310009)
The intake air is only usedto cool the condenser. It does not come into the room.
If you disconnect that hose. You will have a hard time cooling that room.

I read all over the place that it also is used to bring in "fresh air" to keep your room from getting stale. So either that's true or what you are saying is true, but they cannot both be true right?

Anyhow, I'm not going to "disconnect" that hose - currently the hose goes through a hole in wood I placed in the window. And it draws air from outside. What I would do is instead just have that end in the room, with the hose sticking up and drawing air from the room. So that should still cool the condenser right? It should cool it even better since it's cooler inside. But I just want to make sure it's ok to do it like that, and that it won't ruin the AC unit or something I don't know about.


Quote:

Originally Posted by Scuba_Dave (Post 310022)
I have only seen these units with one hose - to exhaust the hot air outside

Yours has 2 hoses?
Where is the fresh air intake hose going?
Are you sure its not a dual exhaust?

Yeah there's single hose and dual hose portable AC's. The dual hose has an intake and an exhaust. It's definitely not dual exhaust. With a single hose unit, the air to cool the compressor is drawn directly from the room (through vents I guess) but with dual hose units it's drawn from outside.

The intake hose on mine goes into the unit.

Here is the manual for my AC: http://www.haieramerica.com/en/asset/product/ebb9084b29

I just need to know if it's ok to do what I'm thinking of doing or if it would hurt the AC unit, or cause some other bad unexpected issue.

Scuba_Dave 08-03-2009 03:05 PM

Every window AC made takes most of its air from the room & then recools it
Some have small vent to allow some fresh air to be taken in
But I usually run them with the vent shut

As long as it is pulling room air you will be fine
If this was a closed/air tight room I might be worried

Gary in WA 08-03-2009 04:24 PM

Been there is correct, the intake air is to take the heat from the coils to the outside. If you put the intake tube in the room, it will be taking all the conditioned air to cool the coils, working in a viscous circle. Due to the proximity of the unit to the tube, the room would take a very long time to cool. Both tubes have to be out the window as directed to not void the warranty (1 year). The pic on page 8 shows the tubes labeled wrong, compared to page 7. Page 9 says (#3) only using 1 tube will decrease the cooling capacity. Which is the same as not hooking up tube to window. Be safe, G

bludshot 08-03-2009 04:50 PM

Quote:

Originally Posted by GBAR in WA (Post 310067)
Been there is correct, the intake air is to take the heat from the coils to the outside. If you put the intake tube in the room, it will be taking all the conditioned air to cool the coils, working in a viscous circle.

When you say "to take the heat from the coils to the outside" that's kind of confusing. That makes it sound like the intake hose takes the heat from the coils to the outside - but that's not correct, right? The exhaust tube takes the heat from the coils to the outside. And the intake tube takes air in to cool the coils. (I just want to make sure I have that right.)


Quote:

Originally Posted by GBAR in WA (Post 310067)
Due to the proximity of the unit to the tube, the room would take a very long time to cool.

I guess the idea here is that the AC unit is blowing out cold air right next to the unit (obviously) and that you wouldn't want the intake tube grabbing that cooled air right away to go in and cool the coils.

But what if I extend the intake tube way up the wall so that it's taking in air from close to the ceiling? Wouldn't that avoid the problem you speak of and be ok to do? Also, wouldn't the cooler inside air cool do a better and faster job of cooling down the coils?

Also, wouldn't the intake have to be sucking in air at the same speed (volume) as the AC is blowing air into the room for it to have this loop/cycle effect? I dunno, I just kind of assumed the intake tube wasn't sucking *that* much air in...


Quote:

Originally Posted by GBAR in WA (Post 310067)
Both tubes have to be out the window as directed to not void the warranty (1 year).

Where did you find that out? The only thing I see is that "damage from improper installation" would void the warranty. But that's the point of this thread is for me to find out if putting the intake tube in the room instead of out the window would damage the unit.


Quote:

Originally Posted by GBAR in WA (Post 310067)
The pic on page 8 shows the tubes labeled wrong, compared to page 7.

Ah yeah, I see what you mean. It's no problem though because I know for sure which is which. The out-take tube gets very warm.

beenthere 08-03-2009 06:03 PM

If you disconnect the intake hose that it uses indoor air.
Then it will use indoor air to cool the condenser coil. And exhaust it outside.
This air will have to be replaced. It will come from other rooms, and from unconditioned outdoor air being drawn into the room and house.

They discovered single hose units don't cool well because of this. And cause high humidity.
Which can cause mold and health issues.

Scuba_Dave 08-03-2009 06:13 PM

Well I guess i'm wrong
The unit we had was quite a while ago & only had the 1 hose
The 2 hose idea makes sense

Does a window AC simply blow outside air over the coils to cool them?
So a window AC doesn't exhaust inside air outside?
That actually makes sense

beenthere 08-03-2009 06:19 PM

Most, if not all window units have an outdoor vent.

A very very small amount of air is exhausted. To force a small amount of fresh air to be pulled into the room.


But, the condenser is cooled with outdoor air only, the same as a central unit.

bludshot 08-03-2009 06:20 PM

Quote:

Originally Posted by beenthere (Post 310107)
If you disconnect the intake hose that it uses indoor air.
Then it will use indoor air to cool the condenser coil. And exhaust it outside.
This air will have to be replaced. It will come from other rooms, and from unconditioned outdoor air being drawn into the room and house.

They discovered single hose units don't cool well because of this. And cause high humidity.
Which can cause mold and health issues.


I think I'm ok there, because the other rooms are air conditioned by a central AC. Even this room is air conditioned by a central AC, but it does an insufficient job. The central system has a fresh air exchanger that works 24/7 keeping the house air fresh. Also, the fan is on all the time so that even when the central AC is not kicking in, air is still being pumped throughout the house and into my room.

So I would think that because of that, air being sucked into the room from the vents and the rest of the house won't reduce my cooling effectiveness, since that air is considerably cooler than my room. Also, I shouldn't have any mold or health issues (at least none beyond what I would have without having a portable AC in my room) right?

(By the way, the reason my room is not cooled sufficiently by the central AC is because of a few reasons:
- it's on the 2nd floor
- I am on the west side of the house in a large room with lots of roof and wall and windows being beat down on by the sun all afternoon. Meanwhile the thermostat is in the rear half of the downstairs where it's coolest in the afternoon/evening, so the central AC does not kick in a lot of the time because the dining room is happily cool enough while my room bakes in the sun.
- I have computers and stereo stuff in my room which heats up the room well into the night.
- The central furnace/AC ducts run up along the outer wall of the house in the walls by the un-insulated garage which is hot in the summer and cold in the winter. Along the ducts they get heated up in the summer and cooled down in the winter, so by the time it gets to my room the central AC air is less cool than it would be otherwise.
- I have to close my bedroom door due to light sleeping family members who go to bed hours before I do.

So by the time I go to bed, it's 29 degrees celcius in my room lol. (without my portable AC unit)

beenthere 08-03-2009 06:42 PM

The central units fan running 24/7 can cause higher then desired humidity.
It should be controlled by a fan cycler. So as not to raise humidity, after the A/C shuts off.


You may be supprised. How much air that portable exhaust.

Go ahead and disconnect the hose from outside.

It will probably help to keep the central unit running longer.

Killmore 08-18-2009 10:53 PM

Removing Intake from portable A/C, not good...
 
Just stumbled on this thread and noticed the issue about disconnecting the intake and having it take in the already "cooled" air from the room. Not a good idea. Although the point that this cooled air will more effectively cool the condenser is correct, the problem with this is that if you use the room's already cooled air to cool it down, it is immediately sent through to the exhaust. So all your doing is sending all the cold air your a/c worked so hard to cool right out the window, literaly! In fact, if you remove the casing on your portable a/c unit and view how the condenser is cooled, you will see that the fresh air's path does not cross the output air (the cooled air that has passed through the coils) of the unit. Another point is that your portable a/c is already designed to re-use the already cooled air, it passes through the filter that you have to clean every week. This is why most portable a/c unit's manuals recommend that you do not block or have the exhaust hose to close to that filter area.:thumbsup:

bludshot 08-19-2009 07:14 PM

Quote:

Originally Posted by beenthere (Post 310124)
The central units fan running 24/7 can cause higher then desired humidity.
It should be controlled by a fan cycler. So as not to raise humidity, after the A/C shuts off.

Yeah, the way it works is we put it in Fan mode and have the fan running all the time, or we can just not have the fan on and then the only time the central unit blows air is when the AC kicks in. However, the fresh air exchanger thing runs 24/7, so if you don't have Fan mode on, then whenever the central AC is not kicked in, the fresh air exchanger is just being wasteful and pulling in air and then pushing it right back out. Seems like it should only be on when the fan is on or when the AC is blowing, but that is not the case - I assume because it is a separate unit from the central AC / furnace.

But I agree with you, I don't like having the fan on all the time nor having the fresh air recycler going on all the time, but it's not my choice. However, somehow, someway the fresh air recycler + fan does *not* seem to raise the humidity when it's on when the central AC is not on, so I dunno.



Quote:

Originally Posted by Killmore (Post 316329)
Just stumbled on this thread and noticed the issue about disconnecting the intake and having it take in the already "cooled" air from the room. Not a good idea. Although the point that this cooled air will more effectively cool the condenser is correct, the problem with this is that if you use the room's already cooled air to cool it down, it is immediately sent through to the exhaust. So all your doing is sending all the cold air your a/c worked so hard to cool right out the window, literaly! In fact, if you remove the casing on your portable a/c unit and view how the condenser is cooled, you will see that the fresh air's path does not cross the output air (the cooled air that has passed through the coils) of the unit. Another point is that your portable a/c is already designed to re-use the already cooled air, it passes through the filter that you have to clean every week. This is why most portable a/c unit's manuals recommend that you do not block or have the exhaust hose to close to that filter area.:thumbsup:


Well, I understand what you're saying, but, Cold air sinks, and hot air rises. Now what I did was take the intake tube and run it up the wall to suck in air near the ceiling. So, in my opinion, the room fills up with cool air in the way it would fill up with water. Then when most of the room is full of cool air and it reaches up to where i have the intake hose, *then* it starts sucking in the cool air that the AC spent so much energy creating - which by that point I don't really care because the room is cool.

All I know is, now that I run it this way, the AC no longer makes me sick. I no longer have the pressure/allergy/whatever reaction to what seems to me like outside air mixing with inside air and making everything feel cool and *damp* (which sucks). Before my forehead would hurt within minutes of turning on the AC. Now, nothing. Now it's great!

And yeah, the intake does suck in a lot of air, and if you close the bedroom door almost all the way, you can feel the air getting sucked into the room from the hallway - which is fine with me since the rest of the house is cooled just fine by the central AC.

I'm pretty sure that my portable AC is running *slightly* less efficiently in terms of making my room cool - but it can still make my room way colder than I'd ever want it to be, plus it no longer hurts my head or makes me sick so I'll take that :p

Killmore 08-20-2009 12:30 AM

Quote:

Originally Posted by bludshot (Post 316638)
Yeah, the way it works is we put it in Fan mode and have the fan running all the time, or we can just not have the fan on and then the only time the central unit blows air is when the AC kicks in. However, the fresh air exchanger thing runs 24/7, so if you don't have Fan mode on, then whenever the central AC is not kicked in, the fresh air exchanger is just being wasteful and pulling in air and then pushing it right back out. Seems like it should only be on when the fan is on or when the AC is blowing, but that is not the case - I assume because it is a separate unit from the central AC / furnace.

But I agree with you, I don't like having the fan on all the time nor having the fresh air recycler going on all the time, but it's not my choice. However, somehow, someway the fresh air recycler + fan does *not* seem to raise the humidity when it's on when the central AC is not on, so I dunno.






Well, I understand what you're saying, but, Cold air sinks, and hot air rises. Now what I did was take the intake tube and run it up the wall to suck in air near the ceiling. So, in my opinion, the room fills up with cool air in the way it would fill up with water. Then when most of the room is full of cool air and it reaches up to where i have the intake hose, *then* it starts sucking in the cool air that the AC spent so much energy creating - which by that point I don't really care because the room is cool.

All I know is, now that I run it this way, the AC no longer makes me sick. I no longer have the pressure/allergy/whatever reaction to what seems to me like outside air mixing with inside air and making everything feel cool and *damp* (which sucks). Before my forehead would hurt within minutes of turning on the AC. Now, nothing. Now it's great!

And yeah, the intake does suck in a lot of air, and if you close the bedroom door almost all the way, you can feel the air getting sucked into the room from the hallway - which is fine with me since the rest of the house is cooled just fine by the central AC.

I'm pretty sure that my portable AC is running *slightly* less efficiently in terms of making my room cool - but it can still make my room way colder than I'd ever want it to be, plus it no longer hurts my head or makes me sick so I'll take that :p

How much is your energy bill?! :whistling2:


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