@Tomas Chao - Driving for dollars can't hurt - yet - with gas this cheap! 

The renters pay electric and gas.

Units - 22 
Rent - 550 (1 at 490, 2 at 500 - old leases) 
Total monthly revenue - $11940Expenses 
His financials from 2015 
Advertising - $0 
Electricity - $177 
Lawn care - $180 
Management - $0 
Maintenance - $0 
Gas - $61 
Pest control - $80 
Phone/internet - $214 
Insurance - $525 
Security - $58 
Trash - $561 - includes units 
Water - $166 - includes unitsTaxes - 615Total monthly - $2635Financing for 20 years 
Down payment - 15% no cash required lender to use existing property as collateral 
Financed amount - $620500 
Rate - 4.5% assumed.

That is taking the "As is" Annual Revenue of $90,780 and subtracting what the owner has as the following expenses; Gross Income: $90,780 Vacancy (5%) (4,539)Electricity (14,400)Water (6,000)Trash (1,500)Gas (3,000)Lawn (900)Maintenance (2,400)Insurance Expense (6,000)Property Tax (5,962)Advertising Expense (600) Net Operating Income: 45,301These are all current expenses not Pro Forma.

For example, you can replace a gas water heater for $900 or $1800 depending on who you call around my area.  

Never consider a park with natural gas pipes.  

Is the heat a separate utility such as natural gas or oil, or is it covered under the electric bill?

I currently have baseboard heater heating and have to pay the entire gas bill my self because its not separated.

If paying for the utilities is in your contract, are you not paying Power and Gas.

I don't know my a*s from my elbow is residential, but I work as an oil and gas title Director for a Fortune 500 energy company with a degree from Wharton.