Can i vent my portable A/C unit through my dryer vent?

Question

I live in a loft in SF and can't vent the A/C to the window as i want to use it upstairs where there are no windows. I do have a washer/dryer combo unit upstairs, however. Can i vent my A/C unit thru the dryer vent? Would i just cut into it and combine the two? THANKS SO MUCH!

Answer 1

Not legally . Must be on it`s own vent . Make a hole in the wall or roof. Keep the vent hose to less than 10 ' or it won`t work properly. Most unit`s won`t work if the vent is more than 6' . Read your instruction manual for an exact lenght as to what will work.

Answer 2

Ditto on all the "bad idea" answers above.

Besides the lint buildup/carbon monoxide/having to put a "Y" fitting in place/ etc there is a sizing problem.  The pipe coming off the back of most portable air conditioners is 5" diameter and most dryers have a 4" diameter pipe.  So not only would you be restricting the outlet simply by using the standard 4" outlet for a dryer but you also want to add it to an existing line that I assume you want to also use.  

Also if set up in a window the unit vent has no return air stopping flap on it.  A typical dryer vent has one and this will restrict the air flow.

Therefore air would tend to go from the AC to the dryer regardless of the outlet.

So here is what I recently did.  I purchased from HD (but look in Lowes or any store that handles ductwork) an external vent that looks like a dryer vent except the diameter is for a 6" pipe. (I don't think a 5" one is common and the 6' one is less restrictive.)  Into that I installed a 6" to 5" reducer. I needed to cut a 5"+ dia. hole into a piece of plywood for mounting.  This was installed in the wall as a back to the 5" dia. adapter that comes with the AC unit.  This adapter has spaces for 4 screws at the corners and is ment to attach to the plate that goes in the window in a normal installation.  A 6" hole is cut through the outside wall and the vent is pushed through, screwed in and caulked.  On the inside the plywood plate is secured in the wall with the 5" end of the reducer going through it.  The adapter is attached and I re sheetrocked the portion of the wall that I cut out to give me better axcess.  

There is a 5" dia. cap that comes with the AC unit and this is installed over the 5" adapter end inside for the winter.  I also put a screen made of 1/4" hardware cloth on the outside of the vent to keep birds from entering.  

The unit is now using this exhaust just fine.  This particular unit sends all condensate out of the 5" Vent line.  I have another unit that produces liquid condensate and for that I am using a condensate pump and a separate liquid line.  

This was done on a standard wood frame construction but could easily be adapted to masonry construction.  If you are a bit handy or know someone who is it should not be too difficult to accomplish.  It is really no more difficult then putting in a vent for a kitchen hood or a bathroom fan.

Edit:  Mr. E inspector would it be a "violation" if it were a kit hood vent or a bathroom vent (probably) or an electric dryer vent? What if it was a duct without a motor (or individual motors like some apartment buildings with common ducts) and therefore not governed by the NEC.  Justin is from Ca.  I know in NYC they have only partially adopted the NEC.  Are you sure it would always be a violation in Justin's neck of the woods?  

With defference to Justin's answer above.  Most techs will proceed with a solution that falls within the disciplines that they are most familiar with.  This is right but it doesn't necessarily make it the best solution.  If you choose to install a Y connector you have to make sure you do install the dampers and you can also get 5" to 4" reducers if you find it is necessary.

The pipe sizes will then fit but what I have said about restrictions also applies and you may be asking the original 5" airflow to be reduced to 4" as well as pass  by 2 dampers.  A ventilation specialist or the manufacturer's tech support could tell you for certain if the restriction (static pressure) would shorten the life of the AC unit or further decrease the efficiency and thus cooling of this relative inefficient type of unit.  Regardless of your decision.  Stay cool (as possible)

Answer 3

Perhaps putting in a window may be the best option. A/C units drip water outside that they take from the air inside, so all the other solutions seem pretty complicated. Or have the A/C unit put through the wall. Or try a large fan to blow the cooler air into this section of the house.

Answer 4

I recently did just this for a job.  Go to the hardware store and pick up a PVC based Y joint to make things easier for yourself.  Make sure it's a 4" Y joint.  And pick up a 5" to 4" reducer (or 6" if that's what the hose size is).

Just remove the dryer vent hose, install the Y vent to the hole in the wall and connect the two hoses to the Y-joint.  If you can, find one with a one way auto damper (or buy two and stick one in each end.  Make sure they open in the right direction, from the appliance to the outside hole) and reconnect the hoses on the damper side.  That'll stop lint and dryer air from blowing in to the condenser coil by restricting air flow back in to the coil.  The dampers usually cost $5.00 to $12.00 and sit snugly inside the pipe.

You'll probably not want to use the AC while the dryer is on.  It'll be counter productive.

We are talking about an electric dryer right?  If it's a gas dryer, ignore eveything I've said.  It's too dangerous to do yourself.  You'd risk carbon monoxide poisoning and that's never good.  Instead hire someone to come in and cut a new vent hole (or buy a 4 or 5 inch hole cutter attachment for a drill and do it yourself).

*Edit*

It's not a code violation in my area to have a lint vent and a warm air exhaust duct connected.  Perhaps some people should stick with Electrical inspections and leave the HVAC to the licensed HVAC guys.

Answer 5

I would advise against it.  I think the condenser of your a/c will get clogged with dryer lint.

Answer 6

Bad idea. The moisture from the A/C condensor will cause the lint to stick inside the vent and back up towards the dryer.

Answer 7

To state it simply: NO.

It would be a Code violation, as well as voiding both the product's listing and the warranties.