If the Landlord pays for the heat, upgrading is a no brainer.

Rentometer is another resource for comp rents.Trulia has a "local info" section with heat maps to visualize data like crime and demographics.

A major overhaul of the heating system is not feasible this week. 

I am working on a 375 sq ft studio apartment and was considering a  slide in wall AC unit with heat.

We also installed a forced air heating/cooling system.  

I own a single family residence that has radiant heating and a swamp cooler on the roof.  

Especially in a market that has been heating up.

I am from San Diego and surely miss the heat and beach!

Your hypothetical is going to be tight any way.I'm assuming 20% down, ~4000 in closing costs and for that you'll pay renovation expense out of pocket.Here is your property as I see it somewhere were taxes are low and insurance is medium:Mortgage Rate 5.00%Length of Mortgage in years 30Monthly Mortgage payment $515.35Taxes $100.00Sewer and Water $-Trash $-Heat/Utilities $-HOA $-Cap Ex and Ops $150.00Insurance $100.00Mgmt Fee $150.00Vacancy $120.00Total Expenses $1,135.35Total Revenue $1,500.00Cashflow/month $364.65Cash on Cash Return 15.63%Same place after renovations:Mortgage Rate 5.00%Length of Mortgage in years 30Monthly Mortgage payment $515.35Taxes $100.00Sewer and Water $-Trash $-Heat/Utilities $-HOA $-Cap Ex and Ops $150.00Insurance $100.00Mgmt Fee $190.00Vacancy $152.00Total Expenses$1,207.35Total Revenue $1,900.00Cashflow/month $692.65Cash on Cash Return 15.68%You get the same return on both properties but MUCH nicer cash flow after renovations.  

Shared heat in multis, for one.