You may also want to check for involuntary liens such as delinquent water bills, code violations etc. 

But you can also find Allegheny County certified master plumbers who live within a zip code using this Health Department page.http://webapps.achd.net/Plumbing/Let me show you how this can work:In the 15025 zip code (Clairton), there are 12 guys on the registry.

Nearly all my properties in the same zip code in South Jackson.

As @Tim Soto suggests, being a postal worker you are in a position to spot neglected properties and can reach out to those owners.I would suggest you keep your postal job until you have accumulated enough real estate/notary/paralegal business.

My only issue is zip codes!

William Byers okay is there a zip code for that area in Jax?

I am thinking of a couple of options1. just paying the amount (~20$/month) for using the space heater if I need to in any particular month2. sending them legal documents (http://legaldocspro.net/blog/warranty-of-habitability-in-california/, http://www.hcd.ca.gov/codes/state-housing-law/hcc/hcc_ap2.pdf, )3. moving out, and getting another placeMoving out is going to be a pain, so I am thinking of either 1 or 2.

I know Texas has a re-key law under the Property Code.

I am currently looking in 7 or 8 area codes where I think there may be some real value for homes in the $100-$150K range, but would like to hear from you all where the demand is.

When I'm looking at sold record in the surrounding area I can only find 1 property within 10 miles, same ZIP code, or even the same use type.