We have new vinyl windows, and want to re-install our Fedders window A/C in
a vertical double-hung window, for which the unit is made.
It was easy with the older windows. I just used a wood frame and screws.
Using screws in the new vinyl window may cause permanent damage, so I need
The A/C unit is small, about 5K BTU. The usable window opening is 21.1" wide
x 13.7" high (53.6 cm wide x 34.7 cm high), large enough to accept the A/C
Does anyone have suggestions?
No more or less than in a wood window. All you need is two screws to be
sure the window is held in place to the sliding expander. In most cases,
once the window is closed, the screw holes will be below the sill and not
Only other way is to make a screw jack of some sort to put above the sash
frame and below the widow frame to exert pressure down on the sash. You can
use 1/2" threaded rod and a coupling nut in the center to expand them.
Depends upon if it's an upper or lower level window. The install kits
that the come with are worthless (only good for temporary use on a
For my upper level I use pieces of hardwood that I cut to size for each
side, stained and varnished (of course). Those go in on the sides. I
have the piece of foam that came with the window unit doubled over and
in the bottom channel of the window. The metal bar that came with the
unit I used as a template to make one out of a piece of aluminum one
inch wide and 1/8 inch thick that goes all the way across the window
and has slots cut to fit the window channel. With my custom aluminum
bar across the top and woddwn pieces on the sides and foam on the
bottom, all that's left needed is to seal it. I stuffed insulation
into some of the bottom areas and then used that metal HVAC tape to
block air flow between everything else. Then I put some
weatherstripping across the top aluminum bar. Trust me, there is no
air leakage going through there! Then I stuffed some insulation where
the upper and lower window meets.
If I were doing a lower floor window, I would want something more
secure, and would have some stainless steel plates made that were U
shaped (but shallow) so I could screw them into the window unit and the
insides of the window itself, that and the coupling thing described ny
the other person.
replying to scott21230, CarolG wrote:
Hi. My main concern was that I did not want to put nail holes in my vinyl
windows. Instead I used 4 pieces of wood:
1) I used a 2 x 4 that fits at the bottom and in front of the vinyl window,
and the air conditioner rests on this board. The length is the exact
measurement of the entire ledge so that the 2 x 4 is wedged tightly on both
sides and cannot come loose. You can make it very tight with shims.
2) I have one board that sits on the outside of the vinyl window in the track
from one side to the other as tightly as possible. The air conditioner sits on
this on the outside of the window. (mine was 1x2x28)
It is important that your air conditioner has a bar that you screw into the top
of the air conditioner. This will hold the air conditioner in the window when
the window is closed behind the outside of this bar.
Now it is time to put your air conditioner into the window as directed, so that
it is resting on the 2 x 4 on the inside and the 1 x 2 on the outside. As you
bring the window closed behind the metal bar it will overlap the bar by a good
1/2" holding the sir conditioner in place.
3) I put two more pieces of wood between the top of the window casement and the
top of the window. (mine were 1 x 2 x 13 each.) This keeps the window from
opening and letting go of the air conditioner (make sure they fit very tightly).
My air conditioner had L brackets, 1 for each side of the air conditioner and I
screwed these to the 2 x 4.
I cut a 2x4 to width of window sill (inside). Painted the 2x4 white. I used
90 deg. angle brackets on each end of the 2x4 and screwed them into the 2x4
top side and into the sides of the window frame (through sheetrock into the
rough frame). I set the AC on the 2x4. The mounting flange of the AC rests
in the vinyl window channel on bottom and one side but most of the weight
is on the 2x4. I then cut a piece of 1/2" OSB (plywood) to fill the space on
the other side. Painted white. The OSB also nested in the vinyl channel on
bottom and one side. Note my AC also has an exterior support bracket
On another house I built an exterior support and shelf with plywood and
2x4's extending to the ground. The shelf resting on the inside sill with
shims to make it level. The AC did not touch the vinyl at all. I also used
plywood to fill in space on the sides.
Thank you all for the suggestions! I have enough info to install the unit
FWIW, the window tech was here today for some window warranty work. He has
20 years experience. He said is was ok to let the unit rest on the small
vinyl front edge at the bottom of the frame, no other support, except to
drive a 5/8" screw at the top of the unit and into the sash.. Use wood
blocks at the top to prevent opening of the lower sash. He'd never been
asked about A/C install in vinyl windows before. Neither had Mitten Vinyl,
my supplier, when I called them.
BTW, it's a 2nd floor window.
windows well off ground here, i put some wood blocks on the brick edge
place the air conditioner resting on the wood blocks, open the
extensions and duct tape everything in place.
we have a fenced yard with doggie door if someone wanted in just come
thru dog door.
air conditioners are haeavy i seriously doubt a thief woiuld mess with
one, easier to kick in door, jimmy lock or break convenient window.
wonder id stats are available oin broke in by removing window AC
1 horizontal bar (I used hardwood) that fits into window channel and screws
into flange on top of AC.
2 vertical pieces of wood on the top on the vertical slider to block the
window from being pushed up.
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