If you also have central air conditioning, the furnace installer can plumb the inside air conditioner drain (A-coil drain) and the furnace drain into the same pipe.Sometimes there are federal, state, or local rebates or tax credits for adding insulation. 

My HVAC guy is telling me that I cannot use conventional wall unit air conditioners and the one that he is proposing will cost me around $1000 each.

Think automobiles, air conditioners.

FYI, The Home Depot on Highland just got in LG 10,000 btu window air conditioner units for $299.00... 

laundry, stains in linens, scratches and gouges, improvements, rearranging what they get their hands in, running air conditioners in and out to storage, mowing, dirty windows, missing screens, hair their sneaked in pets get in awful places, coffee setups, orienting them with questions i never considered, and a lot of other stuff, breakage, restocking things they replace or lose, checking unit to ensure in order, etc.This is far worse than ltrOriginally posted by @Bradley Chapman:I'm not sure what one considers hard work, but I maybe spend at most 5hrs a week combined running two Airbnb's.

Also, the model unit had built-in air conditioner but his unit had big stupid air conditioner. so everything was different than the model unit.and today he said that there was a homeless sleeping at the hallway on his floorso they refused to show him the unit that he already made contract and no one is living, but the unit condition was terrible unlike model unit. is this legal?

They weren't happy about it, but too bad.Oh, and in June we had to replace the compressor for the air conditioner at house #7.

A lot of the older buildings don't have central air, they have room air conditioners. 

Obviously, you have to include the HOA cost in the rent, but you should make the payments to the HOA, yourself, because HOA's are notorious for sticking you with hefty penalties when paying late.You still need to set aside at lease 8% for repairs i.e. the furnace, disposer, water pipes, drains, painting, air conditioner, faucets, etc.150% is high for a vacancy rate.

If you’re paying for utilities what happens when people run the air conditioner and leave the windows open?