Thoughts on incorporating heat and hotwater as a profit?

[William Collins]

I was discussing with a friend today the potential of incorporating heat and hotwater as a profit generation source.   This would of course require 3 base things:  1) efficient utilities- a natural gas hookup in this case, 2) a well insulated house (sometimes challenging in the multi units in New England), and 3) implementation of a landlord thermostat to control the heat and regulate it to a range 65- 71. 

So hear is the example if a unit's monthly heat would be 250 during peak cold months and 50 maximum during the summer months.  Yet tenants are willing to pay @ 200/month for having heath and hot water included.  So the math works like this 5x 250, 4x100, and 3x50 or $1800/year real costs vs $2400/year of what they are willing to pay. That leaves a potential of $600/ month on the table  profit wise.   Does this make sense to everyone?   Does anyone do this?