I'm planning to install a MRCOOL DIY Mini-Split (18,000 BTU) in my office, but I'm unsure about the best way to drill through a cinderblock wall. The wall is the typical one you'd find in South Florida homes. I think I need a 90mm (3.5 inch) masonry core drill bit based on the installation template I'm looking at. Is that correct? I have a regular drill with a hammer function, but I'm considering buying a rotary hammer drill for this process—do you think that's necessary? Also, I've read about using diamond core bits; should I go that route? After drilling, what's the best way to seal the hole when I run the cables through? Any advice would be super helpful since I want to make sure I do this right—don't want any aftermath my wife will remind me of forever!
2 Answers
You could rent a rotary hammer for your project, and I recommend checking out Home Depot for rentals. For a 3.5-inch hole, an SDS Max should do the trick. Honestly, that's quite a beefy tool for an average DIYer to own, so renting might be your best bet!
I went through this last year! Tried a few hammer drills and ended up burning them out. The SDS hammer drill I got from Amazon worked like a charm. If you're interested in brands, I went with 'Berserker' and it's still holding strong. You’ll need a concrete hole saw SDS bit too—got a generic kit from Amazon that worked great! It might take a bit of time to get through, but just keep at it. The MRCOOL kit comes with a plastic sleeve for the hole, so it's pretty straightforward around that.
That shopping list you’re thinking of is solid! Just make sure the bits you choose are appropriate for cinderblock, and you should be good for future projects too. Plus, if your brother-in-law borrows them, it'll be worth the investment!