Cleaning the coils chemically and regularly, helps extend the life of the unit (particularly if located on the outdoors on the ground, in an area dogs roam) and depending on the age and type of unit there may be other internal points of maintenance to perform as well.

YOUR in MICHIGAN,,, not Florida, or CaliforniaRenters can't and don't like to pay to heat them put chemicals in or clean them.Insurance isn't that expensive but the headache and potential for injury or loss of life would make me FILL IT IN.I've managed complexes with pools,, and our company had one death at another complex,, All I can say is fill it in

Buying a building with a huge old gas tank, lead, asbestos, chemicals, lead paint can cost a lot more than $200,000.  

Any changing of chemicals, depending on the state, could result in environmental filings/records being required. 

Even if there was never a chemical spill, future buyers might be overly concerned about this question themselves.

If the home is cleaned spotless to the point we can smell chemicals right before we get there that is a red flag as well. 

I do make weekly trips to water new trees over the summer.I provide filters for tenants and personally spray once or twice a year and write off the chemicals.  

Zinnsser now makes a synthetic shellac called BIN2 which is not as nasty to use and far more affordable.Even after all of that, there have been a few studies which show that the nicotine and other toxins deposited on / absorbed into the walls and trim will eventually re-emerge on the surface.        

Huge amount of capital being spent by big players in the Chemical industry (Big Oil & Gas) in Places like Baytown and on the East side of town.

Unfortunately that’s all dependent on your specific market and the type of hot tub you have and if the cleaner will be financing the chemicals.