I would consider a multi but if not an option I  wouldn't consider the single an Investment until its producing income (option renting a room or two/ possible air bnb).

. $276/year is locked in for life if I decide to continue to use them after 3.5 years.My property has antique HVAC system that is now > 20 years old, so I'm fully expecting them to break down in the next 24 months, and apparently home warranties will replace the unit if they cannot repair it, which means there's a chance that I will get a new furnace and air conditioning unit (~$5000 value) or at least a cash out value.The other benefit is that I own a few properties, and since the warranty is also transferable, so at any time if I feel like another property has weak systems, I can transfer the warranty over to that property and potentially lower my maintenance and capex cost. 

Seems like a costly luxury to add air bubbles in the tub.

Note that current in-place gross income is approximately $315,000.National Road is outfitted with tenant-paid gas forced air furnaces, electric through the wall A/C units, and individual, gas hot water tanks for each unit.

They key is to run it and then completely air out the space after.

My husband served 8 years in the Air Force and has worked for them, as a civilian for 14 years.

, sauna, steam bath, and so much more that I can’t remember anymore :D ... but as an absolute highlight (for me)…there was even a private indoor swimming pool!

You sometimes have to deodorize and air out the space more than once.

And, your tenant's theory on why the door is damaged is pretty spot on:"If there isn't enough ventilation in your bathroom, the humidity in the air can wreak havoc on woodwork such as vanity doors. ...

From my understanding they are like a super air purifier.