You would also require a back up system whenever the temperature drops below the rated threshold of whatever heat pump that you are purchasing.

In my family there have been/ actively are people who have owned or worked in carpentry, finish carpentry, plumbing, electrical, cabinetry, welding, highway maintenance, automotive repair, estate planning, loan officers and commercial property maintenance.

If you have an older house you want to be sure that the bath fixtures are current with anti-scald and the water heater is set to the correct temperature.

Even JB-weld makes a wood epoxy kit.

The new tenant has notified me that the temperature is iffy.

They learned how to weld or do pipe fitting in high school or trade school. 

Look at the water heater (put your ear on it if needed) sometime the temperature and pressure (T&P) relief valve at a water heater leaks.

I had a lot of buddies that went to the Hobert welding school and I have another buddy that owns a brewery downtown Dayton.

Wood framing that is oozing sap has been subjected to temperatures over 200 degrees F and strength properties and metal connections have been weakened.  

An AC is not made to change the temperature 20 degrees at a time.