Category Archives: DIY

Installing Summer Garage AC – MRCOOL Split System

Working in the garage had sweat dripping off of my face after a few minutes of starting a project. The heat had to go! I learned about ductless mini split systems and how easy they were to install without hiring anyone. I found a few kits on amazon that were sold specifically as DIY versions, but costed a bit more than the non-DIY versions. I found a scratch/dent MRCOOL Advantage 24k BTU unit on ebay. The previous owner left behind a spare concrete pad outside the garage utility door which I commandeered for my own purposes:

Installing ductless systems like this one was pretty simple. Drill a hole in the wall where the A/C lines will go, mount the indoor unit to the wall, then run the A/C lines to the outside unit!

The indoor unit, attached on its mount, with coolant lines running through the wall

I ran new electrical to the unit. I only needed 120V for this heat pump, but I ran enough to run a 240V unit just in case the need arises in the future. I quickly learned how hard it is to run THWN wire through conduit, especially when I didn’t use 90 degree sweeping connectors.

Electrical box and lines roughed in. I learned after installation I could have used a sweeping 90 degree bend.Make sure you have your favorite beverage available while working!

The DIY versions of the MRCOOL units come with a copper lineset that is already evacuated, which saves the installer from needing an vacuum pump to do it during installation. I decided to save some money and purchase a vacuum pump kit and do it myself. I watched a handful of youtube videos and did a few trial runs. The copper lineset ends had to be flared so they could mate correctly on the heat pump. I tried the flaring tool at my local hardware store but couldn’t get it to work correctly. Probably a little operator error, probably a little $5 Chinese tool couldn’t cut it. I purchased a better flaring tool and practiced a few dozen times to get comfortable. From what I read online the leaks are most likely to happen at the connectors, so I tried to make sure I got them correct the first time.

Pulling a vacuum and waiting a few hours to see if the vacuum holds.

Admittedly using a gauge like this isn’t ideal to test for a vacuum, but I let it sit for several hours to make sure it wasn’t leaking. I also didn’t have a tank of nitrogen on hand to purge the lines before either.

After the vacuum held for several hours I let coolant into the system by unscrewing the stopper on the outside of the heat pump. Pressure built inside the lines, which I also monitored for a few hours to make sure they weren’t dropping. I put soapy water on all of the connectors to check for bubbles but didn’t find any!

Coolant released into the lineset, time to test!

Now what I had been waiting for since I moved into this house:

54°F air blowing down on me!

One minor downside of this system, the thermostat that controls the system is not wired, it uses IR to set the temperature, turn on/off. Very annoying!

MRCOOL thermostat above the gas fired garage heater thermostat

Every time a change to the system needs to be made the thermostat has to be removed from the wall and pointed at the unit first. This damn thing has wifi, but not a wireless controller??

Back outside I finished up the lineset by covering it with a hide-a-line kit and getting the electrical pvc conduit attached to the siding. I might have taken the amount of drop the condensate drainage pipe needed, but it certainly won’t get clogged up with that amount of fall!

3D Printer Upgrades + Covid Masks

I was printing masks for my local hospital when suddenly my smoothieware board bit the dust!

Don’t leave your printer unsupervised!

I never had very good luck with this board, nothing can be fixed easily on it when steppers break etc. I upgraded to a more modern solution, the SKR 1.4 Turbo controlled via Octoprint running on a Raspberry Pi 4.

New all metal frame

While I was replacing the controller and cleaning up the burnt table I replaced all of the old 2525 aluminum extrusion with new 2020 from Misumi. I got the aluminum corner pieces from RobotDigg.

The new dimensions were slightly large to get more of the print surface inside the triangle for better print accuracy. I upgraded to the e3d volcano hotend for faster printing. I also replaced the old frankensteined SeeMeCnc carriage rollers with linear slides from ebay.

Temporary cross shaft to hold spool
Printing a new mask with 0.6mm layers, much faster!
The print bed can hold up to 6 masks at a time if everything is laid out perfectly

I also got an enclosure made by a family member to keep the temperatures inside up and to also dampen the noise.

Always have your fire extinguisher ready!
Small webcam set up for time lapses
Sent to local hospitals to help prevent shortages.
First multi day print with new upgrades