Does anyone have experience installing heated pipe tape in units that have already been built and are occupied?

Does anyone have experience installing heated pipe tape in units that have already been built and are occupied?

Perhaps there something as slick as a heat map?

Anyone have experience doing a bulk purchase with some sort of suitable heat source for a mobile home?

Also, if the unit dies, you will lose heat and hot water both at the same time and have to repair/replace the entire system.I would stick to a traditional boiler and water heater unless space were a factor to consider. 

I don't do any preventative maintenance unless it's a heating system that services multiple units.

I currently have a 3 family and plan to spend some of it fixing up heating system, painting, and remodeling 3 bathrooms. 

Taxes 45-50k/year with the potential of going up significantly (shouldn't exceed 6% in a single year)Heating PBO = ~$2500/yearwater PBO = ~$1000/yearelectricity for common areas = $500/yearAsking price $800kHere are my calculations, assuming 25% down payment, 800k purchase price, no estimated repairs (although this is wrong, since i'm sure I will have to fix a number of things for the building with no c/o), but I have excluded that building from the income calculations except for scenario B, where I assume i'm able to add $150 rent/unit and a modest 2k rent for the 2nd building.I've also been informed that this will not qualify for conventional loans because it's a mixed use + over 4 properties.

Then I look at other things like heating, electricity, and if the house is insulated/gaps can be fixed.

I am thinking about purchasing a two unit where one side is oil heat and the other is natural gas.