Is there a lot of mechanical work involved (heat pump, boiler)?

Only thing I would add other than turning the water off is be sure the heat is on.

Also, you will have really high utility bills, because your guests will leave the heat at 75 degrees with the window open.You will also have to either get a management company or deal with marketing, reservations, contracts, receiving payments from guests, security deposits, housekeepers, maintenance, keys, etc yourself.

My tenant is refusing to pay rent because of a heat issue.

Was it because they let the heat run out (oil or propane) and the pipes froze?

If the unoccupied units are very cold and there's a way to get power into them, it can be helpful to run a heat lamp on the main supply line where it comes into the unit.When you wrap the pipes, check the R-value of the product you're using and make sure you're using the one that provides the most protection.

And some places have hurricanes, tornadoes, hail the size of baseballs, sink holes, known foundation problems, harsh heat in the summer and severe cold in the winter - all increasing maintenance costs.

I come up with the following expenses:Mortgage Rate 4.75%Length of Mortgage in years 30Monthly Mortgage payment $129.11Taxes $47.33Sewer and Water $-Trash $-Heat/Utilities $-HOA $-Cap Ex and Ops $150.00Insurance $54.92Mgmt Fee $40.00Vacancy $30.00Total Expenses $451.36

If she can't afford heat, what makes you think she can afford repairs?

The rental market is supposed to heat up a lot.