Repair vs Improvement question/clarification.

I inherited a 2 unit rental property, my parents had service contracts for annual boiler maintenance, I continued to use the same service provider.

 

I want to know if the service contracts and fee's count as cleaning/maintenance?

 

Unit 2 needed a repair outside of the service contract, should that expense be listed as a repair?

 

Unit 1's boiler during it's cleaning/maintenance sprung a leak in the heat exchanger due to age, they had to turn off the boiler for a week in November until it could be replaced. Would the boiler replacement be counted as a repair or an improvement? As I didn't choose to replace it, I was required to replace it to restore heat to the unit.