Gift cards, flat screen TV's, gas cards, etc... has never worked out very well - but I get a lot of broke people calling on those ads.The real problem is likely the property and the location.  

The home does not have separate meters for gas/water/electric and all the ducting is connected to the same furnace and A/C... the thermostat for the air conditioning and heater is in our unit. 

I had this same scenario on a gas hot water tank.

And for 5 to 25 units, most of those were built in the 60's, and lots of those during that period only have one water meter, sometimes one gas meter per building as well, and lots of mom and pop owners pay for water/gas/sewer.

Our gas company has a plan, service plus.

Oil and gas fields come to mind.

In a rental property, if you need to replace the water heater, which is better: gas operated vs. electricity operated?

William, Some utility companies have warranty/ service agreements that you pay for every month, i do not know how fast they would come out to repair stuff. i know here in NJ our Gas/ Electric provider, PSEG, has such a program but you pay for it monthly whether you use it or not, i don't know if they do minor stuff, mostly larger appliances. but that may be different with the utility co. by you.

No leins on the property but I just found a gas bill lying on the ground.

@Nick McBrideFirst you have to determine what is your responsibilities of paying and what is the tenants responsibilities of paying.As a general rule - the landlord's expenses/allowance will include repairs/capital expenditures/vacancy/property taxes/mortgage interest/mortgage principal/etcDepending on the county - Water and Sewer can be included in property taxes and be the responsibility of the landlord.Items such as electricity/water/gas is up for negotiation to be paid by either the landlord or tenant depending on what is said in the lease.