If it's hot water it might be worth an investment to separate your zones so that you don't have tenants fighting over the temperature (it'll be different when it's not you in charge).

And if you are in a colder winter climate (like we are here in Milwaukee) you can't do exterior paint in freezing temperatures and FHA won't close. 

Materials expand and contract with temperature.

.`~ First, I would find out what the regulations say about minimum temperature.  

The issue I've ran up against is the mini-split does nothing against the concrete slab which seems to absorb and slow-release whatever outside temperature it's been in the past 12 or so hours.I'm a complete noob.

The problem is that it’s really hard to find a nice temperature for every room (a few of them get really hot, and the tenant constantly keep the windows open.).

They seem to break in the very cold of winter or hot of summer because temperature puts more strain on the metal.

I had a home in Idaho where my management company called me at 8 pm, told me the furnace was broke and the temperature outside was 5 degrees.

What’s the temperature in your local market?

To pick him up at 3 days old, there was a temperature check for me, survey to fill out, exam by a nurse, and that was just to have them hand the baby to me.