• Making a better window adaper insert for a portable air conditioner

    08/05/2022 at 14:20 0 comments

    The other week, I purchased a portable air conditioner.  My house does have a central heat pump, but being over 30 years old, it's living on borrowed time. My area is also hurricane prone, so I wanted something I could easily setup and power off a generator should power be lost, so I selected s small power drawl unit (it uses 795 watts or less) with an effective 5000 BTU rating. 

      Interesting info to know about portable air conditioners:

    While this unit is fairly easy to setup and move around compared to a window a/c, it's a lot worse in terms of efficiency.  A major efficiency loss of this unit is that it's a single hose unit. It pushes hot air blown though the condenser, out the exhaust hose, but the air that's sucked in to be used to cool the condenser is taken in from the conditioned space vs. using outside air.

    Worse yet, pushing air out without a second hose for intake makes the conditioned space a lower pressure vs. outside of the space causing air from outside the conditioned space to seep in.  But it can get even worse, it can not only pull air from outside, but also the attic that's almost certainly far hotter than the outside air!  I noticed this happening when I started smelling the attic and I noticed a warm draft from the closed that hoses the central heat pump fan unit.  I did some additional sealing where the ductwork goes though into the attic to help mitigate this but some air still gets pulled though.

    While the effective DOE 5000 BTU rating does account for outside air being sucked it, the formulas I've seen used, plug in 95F/35C for the highest outside ambient. My attic can get 117F/47C so if there is much of any air drawl from the attic, it's even worse than 5000 BTU!

    Technology Connections has an excellent video about portable air conditioners:

    I would have went with a dual-hose unit, but there appeared to be none to be found at my local store. There are a few that can be found online, but they're larger units that would put a bit more strain on my generator, should a power outage occur.

    The issue with the included window insert:

    One of the most finicky things about the unit is coupling the exhaust nicely with the window.  While the insert is designed to be flexible with a variety of window sizes, gaps are created due to extender portions sliding into the main insert, as the extender portions have to be a bit narrower in order to slide in.

    Worse yet, since the insert, places the hose right at the bottom of the window, and the hose to end adapter is a bit short in length, it's difficult to get the insert security in the window as the window sill gets in the way.)  The end result is using a crap load of tape to compensate, resulting in a mess and also being a pain to put in and remove (wish I had a before picture, but oh well.)

    The solution:

    There had to be a better way I thought.  I started thinking about creating a custom insert.  I first thought of trying to create a perfect insert that the end adapter could clip into but then I realized I didn't have any material that's the exact thickness of the original insert that would be needed on hand.  I decided on a bit rougher of a connection solution, putting the end adapter though the insert. To do so would require either making the end adapter-insert with very tight tolerances with almost no gaps but that would requiring splitting the adapter and connecting the haves around the end adapter or to make tolerances a bit looser resulting in some gaps that would allow maneuvering the end adapter into the hole of the insert.

    I ended up doing the ladder, but I selected some insulating foam board I had on hand.  The material has some flexibility which allowed me me to tighten up tolerances a bit to make things a little more snug, but where were some gaps left, below is the first version of the custom insert (wasn't used in the end as I fudged up the length cut):

    On the version that actually successfully went in,...

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  • Murphy strikes with a vengence! (My adventure in changing a failing drive belt on a mower part 2)

    05/05/2022 at 19:37 0 comments

    The replacement drive belt came in the mail today to replace on the one I damaged in part 1.  I put it on with care and made sure that it wasn't rubbing against anything it shouldn't.  Before I continue on I should note that the owners manual actually has directions on replacing the rear-drive belt as shown below.  My method is not exact, but similar.  I should mention that what I've been calling a tensioner pulley is called an idler pulley in the manual. A picture of the relevant page is shown below:

    That did not go as expected

    I then went to re-install the battery and thought I was done. I fired up the mower, only to find it won't actually move when put into gear. I quickly shut it off to avoid damaging either the front or rear drive belt.  The rear drive belt looked okay. The front drive belt overall looked acceptable, but it is starting to show some signs of aging, but not nearly as bad of shape as the original drive belt was. I felt the front drive pulley on the engine and it felt what may have been a little too warm, indicating the front drive belt was slipping, perhaps due to too much resistance to turning.


    Fiddle, fiddle, fiddle, and fiddle some more (and cats)

    At this point, I spent around 2 hours fiddling with things. I changed the drive speed and I loosened and tightened bolts that were involved when changing the belt.  I also move the position of the front drive belt every time I fired up the mower to avoid too much heat buildup.  Two of my neighbor's cats decided to come over and watch me (and perhaps snicker) in my frustration.


    Heck, lets try sticking on the original replacement belt that was damaged

    After fiddling with it fell short, I decided perhaps I should stick on the original replacement belt that was damaged.  I put it back on. I fired the mower up, won't go into drive. I try again. It decides to actually go into drive.


    Fine, it if you want that drive belt, you can have it!

    Around 3 hours wasted only to find the mower only wanted to play nicely with the damaged belt. It can have it! Hopefully even damaged, it will last a bit.  Perhaps things might have went better if the front drive belt was also replaced, but I don't feel like going down another rabbit hole for the time being.

  • My adventure in changing a failing drive belt on a mower

    04/29/2022 at 17:44 0 comments

    I'm not a small engine/equipment mechanic, I just play one in real life!

    For the past 2 years or so I've been finding some chunks of what appeared to be a belt.  Sure enough, upon inspection, the rear drive belt had chunks missing on it. Happy to say the front drive belt still appears in reasonable shape, as that one would have been quite a chore to change. It's not terribly surprising that it's the first belt to go on its way out as there's a tensioner pulley that puts additional stress on it.   It's amazingly things have held up for as long as they have as it's an MTD mower that's 20+ years old (and more then likely well over double it's  life expectancy, I imagine it's one of the few of this particular model that isn't in a scrap yard.)

    First challenge: getting the old belt off:

    The plan was to slip the belt off of the connecting set of pulleys that links the front and rear drive belts together via a gap between the top pulley (that the rear drive belt uses) of the set of pulleys and the body of the mower.  The problem was that the gap was too narrow.  I looked under the mower and studied the assembly,  I initially thought I would need to take apart the pulley assembly which would have been quite an ordeal.

    There had to be a better way, and there was

    There's gotta be a better way to do this.  I then saw the solution.  I noticed that the assembly was connected to the body by a bolt (the one with the large washer by the yellow spring in the photo below.)  If I loosened/removed it and pop it down a bit, I might be able to enlarge the gap enough to remove the old belt and get the new one on. Sure enough it worked. 

    With a bit of a struggle, I got the old belt off and below is a side-by-side photo of the old and replacement belt:

    Here's the view under the battery compartment with it around the other pulley (and in position with the tensioner pulley.)

    What's that smell? (Murphy's Law strikes!)

    At this point everything initially looked fine and I put the battery back in place.  My first clue should have been that the assembly was not freely turning when the mower was in neutral. I fired the mower up and drove around a bit. I then started to smell the burning of rubber after a bit.  I took the battery back out and inspected the belt.  The inner portion of the belt took substantial damage. I then saw the issue. Turns out there was a belt guard pin that it was rubbing against. Crap. Turns out it was hidden from view behind the bolt assembly that connects the pulley assembly to the body.  The good news at least is that it was easy to remove, put the belt in the correct position and re-attach. Below is a photo of the darn belt guard pin with the belt positioned correctly:

    "We do it right, because we do it twice!"- Mustie1(Darren)

    While the (now) damaged belt would still last for a bit, I ordered another belt, and hopefully get another 20 years out of it.  Now that I know about the belt guard pin, I can simply remove it before hand, which should make changing out the belt the second time go a bit easier.