I'd just keep the oil boiler and focus on system efficiency.

This is VERY common as more houses get high efficiency windows.  

But it was a lot of wasted time and energy on people who wanted to sell me deals I didn't want to buy.

I've found a few driving by, but I'm wondering if there is a more efficient way of doing this.

Another way is to pull a cost efficient list of absentee owners from listsource.com searching for the quantity of units you're looking for.

Then after closing we replaced the old oil furnace with efficient gas furnaces and separately metering the heat it increased the CAP Rate overnight and made it now much better than the averages in the area.  

Some kind of usable outdoor space.Cost/effort of upkeep: Reasonably efficient utilities.

I want to invest as efficiently as possible.Background: Our strategy is to build up a few rental properties in our portfolio while we are young.

If you want to grow and scale the most efficient way is flip and develop properties and grow your cash or do larger rental properties and grow your can flow.

This property was owned by the previous owner for 5 years and allowed my partners and I the opportunity to find an asset that had rents at 8% below market, only 10% of units needed to be renovated, and the previous owner was not very efficient on their costs.