Need To Extend The Portable AC Vent Tube By 4 Feet - HVAC - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 05-02-2014, 12:31 PM   #1
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


Most portable AC units come with a 5 foot long 5" vent tube. Manufactures warn that extending the tube will void warranty. Some web information site say ok if you increase the extension piece to 6" flex but never go more than 10 feet total. Can we please have a discussion of this? Please. --jaes

Advertisement

jaes is offline   Reply With Quote
Old 05-02-2014, 12:38 PM   #2
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


How will they know what you did?

Obviously you don't want it to fail but going 10 feet with 6" should be OK as long as it has NO kinks IMO.

If it has too much resistance it will overheat and fail.

Advertisement

__________________
"Cut it twice and it is still too short".

Last edited by yuri; 05-02-2014 at 12:41 PM.
yuri is online now   Reply With Quote
Old 05-02-2014, 01:37 PM   #3
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


Yuri, thanks for the reply. The space to be cooled is in a 200 sq ft area in a basement that has stone foundation walls. The portable AC will set in an "alcove" in the basement wall ---directly behind that alcove is a crawl space --that is 9 feet to an exterior wall where I am going to vent the AC tube. To cut down on the air flow resistance, that you mentioned, I've been thinking that I could use a length of Schedule 80 6" PVC pipe. What do you think? ---smooth inside of the PVC would certainly offer less resistance than the "ribbed" inside of flex tubing??? Please, anyone please enter the discussion. ---jaes.

Last edited by jaes; 05-02-2014 at 01:40 PM.
jaes is offline   Reply With Quote
Old 05-02-2014, 02:02 PM   #4
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


That is VERY expensive pipe. I would use cheaper 6" galvanized or aluminum pipe and HDepot should have it. I was going to suggest smooth pipe. Do you really need cooling down there? They make combo portable de-humidifier, AC units also that vent like what you are talking about. Drawback to basic de-humidifiers is that they need to get rid of the heat but if you can dump that into the cold basement then a cheaper de-humidifier may do the job.
__________________
"Cut it twice and it is still too short".
yuri is online now   Reply With Quote
Old 05-02-2014, 03:03 PM   #5
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


Funny you should mention the AC and de-humidifier combo. You are correct, cooling isn't the problem ---humidity is. Now, I have a small 5,500 btu window AC that cools the place well enough in hot summer months. (I am making the window an egress window so window AC will go). In summer, and especially winter, I need to have a de-humidifier in the space. ---Yes, I am installing a portable, combo AC and de-humidifier (separate functions). QUESTION: Should I be concerned about condensation build-up in the vent tube---especially when it is running through the unheated crawlspace? For example when I using the dehumidifier function in the winter? ---should I, somehow, insulate the tube? --even in the summer, would it be wise to insulated the tube-- when AC function is used? --jaes
jaes is offline   Reply With Quote
Old 05-02-2014, 03:41 PM   #6
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


I am looking for a new dehumidifier for my basement and noticed Sears has combo units. I doubt they are meant for Winter use as cold air will migrate back into the exhaust pipe and freezeup the unit. I think the idea is that when you just need dehumidifying then it can do that w/o cooling the room. You would need a separate dehumidifier for Winter use and empty the bucket or hook it up to a floor drain. Some now come with pumps. The separate dehumidifier will warm the basement and that works for me.
__________________
"Cut it twice and it is still too short".
yuri is online now   Reply With Quote
Old 05-02-2014, 05:05 PM   #7
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,554
Rewards Points: 4,746
Default

Need to extend the portable AC vent tube by 4 feet


If the portable is a single pipe unit. Then it will draw air from other areas to make up for the air its exhausting. if that air happens to be from the crawlspace, then you may end up with higher humidity.
__________________
When posting in certain forums, knowing your location will help others give better feedback/advice/solutions to your questions.
beenthere is online now   Reply With Quote
Old 05-02-2014, 05:34 PM   #8
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


The combo unit I have has one 5" exhaust flex tube out the back. Now that we are talking through this situation, I believe the unit only pulls air from the basement area (not the crawlspace) when it is in the "cooling" or "dehumidifying" function. ----I believe the 5" exhaust tube only functions to blow out the hot air when the unit is in the "cooling" function. ---This realization only occurred to me after our discussion in this tread. So, condensation, in the winter, may not be a problem; because unit will not be in the "cooling" mode. You can bet that I am going to phone the manufacture to make sure that these assumptions are correct. ----I thank you for talking me through this situation. ---Your responses were quick and helpful. ---jaes.
jaes is offline   Reply With Quote
Old 05-02-2014, 05:55 PM   #9
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


You may be wrong. The compressor in the unit runs in cooling and dehumidifying and produces lots of heat and that heat/air has to go somewhere. Probably they use that exhaust tube for both cooling and dehumidifying. Any time you have a open pipe to the atmosphere wind can blow in and cold transmits thru the pipe and it gets cold and depending how cold your area is that may be a problem. I have a basic dehumidifier and it has a fan that blows across the compressor/condenser and puts heat in my basement which I don't mind and want. It probably has 2 fans. One to pull air in from the room and dehumidify it and shoot back in the room and another which takes ambient air from beside the unit and passes it over the compressor/condenser and shoots it outside. Beenthere is correct the unit does exhaust air from the house and it will come in the easiest location which may be around doors or windows or the crawlspace but there is nothing you can do about it. It will create a negative pressure and air needs to come in somewhere to replace it.
__________________
"Cut it twice and it is still too short".

Last edited by yuri; 05-02-2014 at 06:01 PM.
yuri is online now   Reply With Quote
Old 05-02-2014, 06:41 PM   #10
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


They also don't have a drain bucket for the water from the cooling/dehumidifier coil. They evaporate that water with the exhaust fan and shoot it out the exhaust tube.

Dehumidifying runs the compressor and uses the cooling coil. Fan runs at a lower speed to get more moisture removal than in AC mode but technically it is still in the "cooling" mode, refrigeration wise.
__________________
"Cut it twice and it is still too short".

Last edited by yuri; 05-02-2014 at 06:46 PM.
yuri is online now   Reply With Quote
Old 05-02-2014, 07:11 PM   #11
Member
 
Join Date: Nov 2013
Location: Winnipeg, Canada
Posts: 1,162
Rewards Points: 1,440
Default

Need to extend the portable AC vent tube by 4 feet


Quote:
Originally Posted by yuri View Post
. Beenthere is correct the unit does exhaust air from the house and it will come in the easiest location which may be around doors or windows or the crawlspace but there is nothing you can do about it. It will create a negative pressure and air needs to come in somewhere to replace it.
You can buy dual piped units as well. They intake air from the outside and exhaust it back to the outside. These units cause no negative pressure problems.

Quote:
They also don't have a drain bucket for the water from the cooling/dehumidifier coil.
You can get them with collection containers (actually they are convertible. You can run them with a drain bucket or connect a drain hose to them).

@OP
They suggest not extending the pipe work because they can get pretty hot (I have an 8000 BTU unit and it gets pretty hot).

The flex tube causes a lot of air turbulence (resistance) as the air travels through it and it doesn't take a lot of extra tubing to cut the effective air flow down to nothing. If you want to extend then I would get rigid (oversize) ducting to cut the resistance as much as possible.
Bob Sanders is online now   Reply With Quote
Old 05-02-2014, 07:18 PM   #12
Member
 
Join Date: Nov 2013
Location: Winnipeg, Canada
Posts: 1,162
Rewards Points: 1,440
Default

Need to extend the portable AC vent tube by 4 feet


Quote:
Originally Posted by jaes View Post
The combo unit I have has one 5" exhaust flex tube out the back. Now that we are talking through this situation, I believe the unit only pulls air from the basement area (not the crawlspace) when it is in the "cooling" or "dehumidifying" function. ----I believe the 5" exhaust tube only functions to blow out the hot air when the unit is in the "cooling" function. ---This realization only occurred to me after our discussion in this tread. So, condensation, in the winter, may not be a problem; because unit will not be in the "cooling" mode. You can bet that I am going to phone the manufacture to make sure that these assumptions are correct. ----I thank you for talking me through this situation. ---Your responses were quick and helpful. ---jaes.
Most of these "dual a/c dehumidifier" are a crock of rubbish. An a/c naturally removes water from air, but these machines still "cool" as they dehumidify.

A true dehumidifier on the other hand intakes air and runs it through the evap to remove the water, but they also go on to the extra step of running that cool dry air through the condenser to warm it back up again before it's expelled back out into the room. The end result is an air output roughly the same as what was taken in (plus a few degrees for the heat of compression given off

Most of these"dual" units don't do that last step to warm the air back up again.
Bob Sanders is online now   Reply With Quote
Old 05-02-2014, 07:39 PM   #13
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


Thanks to Yuri, Beenthere, and Bob. --(1) I am going to check with the company about how their combo unit works in the dehumidify mode. (2) Seems like, from what you say, it would be a positive thing to use smooth interior vent pipe/tube to lessen the air flow resistance. --- I am going to use a short length of the factory's 5" flex (2ft long) to get off the back of the unit, then transition to 6" smooth for the rest of the 9 foot run. I might insulate the outside of the run. Sound ok? ---Thanks for all the helpful discussion. ---jaes.
jaes is offline   Reply With Quote
Old 05-02-2014, 07:53 PM   #14
Member
 
Join Date: Nov 2007
Posts: 33
Rewards Points: 25
Default

Need to extend the portable AC vent tube by 4 feet


Bob, I was busy typing my last post ---so I wasn't able to see your last post before I hit the "submit reply" button. From what you say, it sounds like a straightforward dehumidifier (no combo) is really what I should put in that basement alcove ---beside pulling out the humidity, it would provide some heat in the winter months. ----problem is, I really do need a small bit of AC in the hot summer months. Maybe I should put a portable AC in the alcove just for cooling. ---and put a regular dehumidifier off in the corner of the basement area--- somewhere. I am bit disappointed to hear that combos are crap ---because using two separate units is going to take some extra space. ---jaes
jaes is offline   Reply With Quote
Old 05-02-2014, 07:56 PM   #15
Hvac Pro
 
Join Date: Nov 2008
Location: Winnipeg, Canada
Posts: 10,122
Rewards Points: 882
Default

Need to extend the portable AC vent tube by 4 feet


They are finely tuned and engineered to work with the pipe they recommend so you are going into uncharted waters. We don't know what is going to happen either. Especially if it is windy the wind pressure may be enough to overload the fan in that unit. They don't overbuild anything these days or give you extra capacity for nothing. I would want the 6" pipe as close as possible to the unit so the flex pipe does not restrict it at all.

Advertisement

__________________
"Cut it twice and it is still too short".
yuri is online now   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
tube skylights w/ vent? cbzdel Building & Construction 4 09-16-2011 04:25 PM
New Roof marknok Roofing/Siding 4 08-06-2011 12:41 PM
Extend height of interior balcony railings by feet? denemante Building & Construction 5 10-23-2010 05:18 PM
Low-Slope Ventilation - Cobra Fascia Vent and Cor-a-Vent Roof-2-Wall vent atulc Roofing/Siding 7 08-22-2008 11:40 PM
extending my direct vent exhaust tube brianbh HVAC 5 02-13-2008 04:25 PM




Top of Page | View New Posts