Upgrading from window units to a central HVAC system or mini-splits can be a game-changer for multi-family rentals.

If you can plant a mini forest between yourself and the source of the noise you'll be surprised how much sound can be diffused (have you ever hiked in a forest that was eerily quiet?).

Have used state programs to upgrade all windows, insulate, instal 3 mini-splits in main home, 1 in ADU in main house; turned garage building with 2 ADUs from oil heat to mini-splits.

My wife and I want to research investing in mini-storage facilities.  

This allowed us to move down to rural Ethridge, TN where we bought a mini farm that had a guest cabin.

@Dominic Gilbert - I faced the same problem and went with a mini split. 

The cabin isn’t the attraction, but more of a welcome place to sleep and enjoy a cup of coffee.Large cabins are trying to be the attraction - almost like a mini amusement park.  

Sale price: $175,000 Key Features & Upgrades-New roof, fresh interior & exterior paint-Luxury Vinyl Plank (LVP) flooring throughout-New doors with updated locksets-Rekeyed locks & updated hardware-New kitchen cabinets & quartz countertops-Updated bathrooms with tiled tub surrounds, new vanities & toilets-New light fixtures & mini blinds-Full HVAC replacement (686) & condenser/A-coil (688)-New water heaters, plumbing updates & landscaping

Each unit features 2 bedrooms and 1 bathroom, providing a total of 4 bedrooms and 2 bathrooms across 1,684 sq. ft. of heated living space.Key Features & Upgrades:New Roof for long-term durabilityFresh Exterior & Interior Paint for a modern and inviting lookNew Interior & Exterior Doors with updated locksets for added securityLuxury Vinyl Plank (LVP) Flooring throughout, combining style and durabilityFully Renovated Kitchens featuring brand-new cabinetry and quartz countertopsUpdated Bathrooms with new tiled tub surrounds, vanities, and toilet seatsNew Light Fixtures & Mini Blinds installed throughout the propertyComplete HVAC System Replacement for Unit 686 & New Condenser & A-coil for Unit 688Plumbing Upgrades including new water heaters, updated faucets, leak detection, and a cleanout drain installationSecurity & Hardware Updates with rekeyed locks, new smoke alarm batteries, door hardware, and cabinet adjustmentsNew Landscaping to enhance curb appealThis turnkey property is ideal for homeowners or investors seeking a low-maintenance, move-in-ready duplex in a prime Memphis location.

We remedied the situaiton by installing 1 mini-split on the lower level.At another ranch house with boiler heat, which the previous owner had updated with a newer high efficiency unit shortly before our purchase, we added central air with the entire unit and all the ductwork in the attic.