this is if you have forced air, most around here have baseboard heat with a boiler so no filter needed. If you do have forced air, make sure you get the right type of filter. Too high a rating filter on an older furnace can make it work harder than it needs to. usually an 8 merv is good for most furnaces. And you really only need to change it every 3 months.

if you have a boiler you should make sure it has adequate water in it, your inspection report should have told you if it already has an auto water fill component or not, in which case it makes it much easier.