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. 

This is what one company's tune up entails:Spring AC tune up:Indoor Unit*Blower Motor *Amp Draw *Bearings *Blower Wheel Balanced *Control Board *Operating Properly *Incoming Voltage*Connections *Low Voltage *Electrical Connections *Change/Clean Filter *Capacitor *Thermostat *Check Operations *Outdoor Unit*Compressor*Amp Draw*Condenser Fan Motor*Amp Draw*Bearings*Capacitor*Electrical Connections*Clean Condenser Coil(water)*Check Refrigerant Levels*Check Contactor *Relays Operation*Check Operations*Clear Condensation Lines*Furnace:Fall Maintenance Checklist*Replace Filter*Electrical Connections*Check Thermostat*Verify Blower Condition*Check Control Operations*Check Control Board*Check Capacitor(s)*Amps of motor operations* Check Relays*Heat Exchanger Condition*Burner Condition* Remove and clean flame sensor* Inspect Blower Wheel*Inspect and check ignition operations* Check ALL safety operations* Verify a good clean burning flame*Are these pretty standard work supposed to happen for tune ups? 

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.