It is far cheaper to replace it now when you can take your time than an emergency replacement when the boiler dies.Given your expected hold period and a typical boiler life of 15-20 years, it looks like you will be replacing the existing unit during your ownership. 

So, if you have a small cash reserve (emergency fund) and a 401k, and maybe are investing in some equities (mutual funds, stocks, ETF)...then maybe you only have "X" amount for real estate and what to focus on a single play/strategy/deal that you believe in.I really like the approach @Joseph Firmin lays out and I think a lot of individuals get overwhelmed - "wait that sounds like a lot of work/time...I have to do that for every deal?". 

I.E, ceiling height for the basement, windows for emergency exits, parking etc.Monitor posts when individuals ask for recommendations provide valueJoin FB REI groups in your state, county, city whichever is available -> ask for wholesaler recommendationsKeep an eye on the BP marketplace see who is wholesaling in your area, if there aren't any, contact the ones who post most consistently ask if they know someone who knows someone in your area.Check out your county's/city's cash-buyers list, -> build a relationship -> ask for wholesaler recommendations (and possibly money)Contact active RE Agents/Property Managers in your area -> build a relationship -> ask for recommendationsThere are YouTube channels about REI DM/post comments -> ask for recommendationsCreate FB ads " I buy ugly homes in XXX area"Get comfortable with the idea you may have to invest out of your area/state.Hound the auction webpages to the individual cities/counties your interested in (not the well known auction sites)Read publications about legacy cities with high vacancy/home abandoned rates due to industrial HQ moves or what I call industrial to IT changes or the 2008 Housing Crisis ( Baltimore, MD. 

You may save money today to patch things together but in the long run spend more with repeat issues.All of these things cost money as well as emergencies, have cash reserves to cover them.  

Although my business is mostly focusses in SoCal I am open to newer emerging markets in the US.  

Yes, I have a job that produces income (moderate/average income) and a comfortable emergency reserve.

Hot water is nice to have but not an emergency if you got right on it.

It sounds very similar to our situation in Calgary where migration is excellent, inventory is abysmal and new growth sectors are emerging.

If you are concerned about price points and current valuations then you need to find an emerging market where you can achieve a bigger bang for your buck.

If this is a real emergency situation I can allow it and start looking for a new tenant, but is it appropriate to ask for any medical papers?