Mailing to a group like code violators would also be great IF you could isolate the ones with equity.The list of names is CHEAP compared to the 6 month cost of mailing to it.  

The gain allocated to the primary residence portion of the property would qualify for the 121 Exclusion, which means that up to $250,000 in gain, if the person is single, or $500,000, if they are a married couple, would be excluded from taxable gain under Section 121 of the Internal Revenue Code ("121 Exclusion"). 

You should, at least once, that would be every 6 months.Repairs or improvements may not be made by a residential tenant that would be required to be depreciated, doing so leads to false tax deduction and depreciation schedules under the tax code, those tenants can not claim such expenses, if you do it's really fraud if you didn't pay for it.My rule is that if anything has to be opened up, unscrewed, disassembled or disconnected to repair it, it's my thing, not a tenant.

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.

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.