This means making sure all rooms receive heat and airflow on a consistent basis.

I submitted the refund request the next day and the host informed me he would not refund me because the unit was not advertised as having a heat.... he was wrong, but even if he had been right, it’s concerning that someone would be okay renting a unit in freezing temps without heat.

In other words, while I wear sweats around my house in the winter, I've been to houses where the owner pays the heat and find the tenants walking around in boxers and t-shirts.

We purchased a roughly 1000sqFt house and had plans to add a kitchen, door separating the upstairs and downstairs, and other elements to the basement to suite it.

We did have a fire once when the fire caused the nails in the floor joists to heat up so much it caused a fire below the hearth. 

I have already tried setting the thermostat to 70 degrees and having it in a lock box to manage heat/hydro consumption... but they just break into the box and crank the heat back up, or plug in space heaters to keep the house at 75 degrees.

With heat, I can bring in space heaters temporarily, and in some cases I have redundant heating methods eg a minisplit that also heats but isn't primary heating method.   

Any broken pipes have to be replaced but you should go through the additional expense of upgrading the entire plumbing system to pex because it is more resilient in cold temperatures.I know politicians and media claim the earth is heating, but I am expecting more cold weather in the next ten years and people should prepare for it.

@Mohr Ben-Reuven - "The Real Estate Rehab Investing Bible" by Paul Esajian has a great overview of the elements associated with a rehab and general costs.

In fact, I don't have a furnace - the tankless heats hot water loops below the slab.