Shopsmith Forums

So I have a portable AC unit for my master bedroom because my wife prefers to sleep in the arctic at night and I don't like the bill for cooling the entire house that much. Right now we have the unit connected with the cheap plastic "one size fits all" spacer in a standard, double pane, single hung window. It works alright, but it's in the way where it is and I'd like to move it. We also are getting quite a draft off of the current window insert, that the thin heat shrink plastic just doesn't do a good job of curing for us. It's also a pain to remove, so it stays in place year round.

Instead, I'd like to make a window insert out of a piece of 3/4" plywood to put into one of our two 3'x1.5' (WxH) sliding windows. My intent is that this be something that can easily be removed from the window and the original sliding pane replaced, if we so choose to. I'd also like this to be an operation that my wife could do unassisted, or my 8 year old if we tell her to give it a shot. I plan on removing the glass pane altogether when the wood insert is put in place.

The issue I'm running into right now, the one that is keeping me from moving forward at all on this project, is how do I do weatherstripping on this plywood to make a good tight seal against the window frame. I'd prefer to keep from having drafts. I don't think foam is really an answer here. To install this piece you have to first tilt the top of the plywood into the opening, raise the plywood into the channel, then rock the bottom over the bottom channel, then slide the window down into both channels slightly, then slide the plywood to the right to get to the closed position of the normal window pane.

The normal window pane that is in place currently utilizes wool pile weatherstripping on the outside face side of the window on three sides, and an interlocking channel along the trailing edge of the pane. I'm not familiar with a method to attach wool pile weatherstripping to the face of plywood, especially near the edge, or any product to use there.

I have thought about using spring bronze as that was the weatherstripping of choice on the doors where I grew up, but haven't found a source for that yet and not sure if that would work for me.

I'll get some pictures of this later when I can get some light on it and show what I mean if I'm being completely unclear about this.

So...thoughts, suggestions, comments??

I note that you have a sliding window; what I have was designed for a wooden double-hung window but might be applicable to other window designs with modification.

Some years ago I designed and fabbed (with my Shopsmith of course) an AC holding frame. I was not satisfied with the flimsy manufacturer-supplied window-install components that typically come with the AC unit. AC units are heavy! I wanted something that would securely hold the AC unit in the window frame in the correct (5 degree tilt) orientation and be weather- and burglar-proof (kicking in the AC unit is a favorite way dirtbags break into houses where I live).

Images attached. The holding frame is in the basement now (for the winter), but I took a picture of it, and the AC unit.

I designed the holding frame in CAD. Had to model my existing window frame and also the AC unit. A lot of design work but it has paid off for me. Whatever you come up with, it needs to be able to bear the very heavy weight and overhung load that the AC unit will impose on your existing window frame. With modern crappy PVC window frames in use today, I am surprised that more AC units are not tumbling out of windows everywhere.

I like the interlocking design of your frame. Looks like it is well thought out. I've used window units in the past, but right now we're using a portable unit and the only part that goes into the window frame is one end of two large hoses, since I have the dual hose kit. Most portable units come with a single hose that exhausts hot air outside, but with a dual hose kit the air that is warmed up comes from outside instead of from the room that you're trying to cool down. I have room for both of these hoses to terminate on the plywood board and miss the frame, as I've already checked on that.

I did find a source for the spring bronze weatherstripping at a local ACE hardware, so I may give that a try. I also have to make up the difference between the thickness of the 3/4" plywood and the sliding window sash, which this will help with some. I haven't checked to see if I need to add more thickness to it beyond that or not. And yes, I do plan on using a good quality exterior paint in multiple coats on this board. The window is higher up on the wall under the overhang of the roof, so I'm not expecting any moisture on it other than condensation, which we get a lot of in the Houston area.

Nice . years ago we built frames with plywood fillers on one or each side and added a stop above the window, we never had a issue however your design looks much better .

Do you add a stop above the window so it doesn't slide up unwantedly ?