Get a Kindle and buy/download What Every Real Estate Investor Needs to Know About Cash Flow And 36 Other Key Financial Measures by Frank Gallinelli 

Don't measure in regards to reward... measure in regards to risk.

And 36 Other Key Financial Measures

In theory the meter would go between the boiler and the thermostat and would possibly measure the amount of time water is circulating?

She will come out for free to measure and give layouts.

"Measure twice, cut once"By that I mean, do you due diligence.  

My thought, however, is that the "sweet spot" on the spectrum is really at the lower end of Value Add (approaching rehibilitation but not there).I'm thinking the sweet spots for my first investment should be:1) 20 Units in Value Add 2) 5-10 Units in RehabBoth of these conditions would be coupled with some quick financial measure to identify properties that warrent further research, perhaps by applying the 2% rule to the sum of purchase cost + upfit costQuestions for those of you with experience in this space1) What is your Sweet Spot and why?

Property values are subjective and even an appraisal is not always the best estimate of actual ARV esp. if there are a lot of foreclosures in the area but it does provide a generally accepted measure of value.

According to the recently released Nationwide Health of the Housing Market Report, Philadelphia follows Pittsburgh, PA and Cleveland, OH as the top housing markets in nation.See links below for more information.http://www.marketwatch.com/story/nationwide-unveils-broad-measure-of-us-housing-landscape-that-signals-healthiest-outlook-since-2001-2015-03-31http://www.msn.com/en-us/money/realestate/where-are-the-healthiest-us-housing-markets/vi-AAajaf4?

A lot of real estate books don't go too heavy into calculations, but if you're like me you'll really appreciate Frank Gallinelli's book, What Every Real Estate Investor Needs to Know About Cash Flow ...And 36 Other Key Financial Measures.