Every investment you buy should come with an adequate "margin of safety" that takes into consideration:* Potential upside (how much you can make)* Amount of effort needed* Risk (usually measured in 'how much you are paying')The higher the risk and effort, the more 'margin of safety' you'd like built into the deal.RULE OF INTELLIGENT INVESTING1.

Investing in Income Properties: The Big Six Formula by Kenneth Rosen, Wiley & Sons publisher, and Cash Flow & 36 Other Key Financial Measures by Frank Gallinelli,  McGraw-Hill publisher, are the two texts I highly recommend.

The only reason the the Mitsubishi and Fujitsu units claim to be efficient only down to -13 (Well, Fujitsu says -15 but they use the same standard test which measures down to -13...) is because the lowest test standard is -13F, in the real world they produce great heat at the absolute lowest temperatures Maine can ever experience.

Bottom line is pick one; do it to the best of your ability; measure your results and then refine the approach or move on to a different method.

The ability of non-bank mortgage servicers to internally measure, monitor, and mitigate risks inherent to servicing will help increase the financial strength of non-bank servicers and is a prudent business practice.

I have had friends and family email pictures to me, along with exact measurements of rooms, windows, doors.

We'll get it re-measured and also discuss the price further...One question, are your comps for wholesale or retail price? 

They were taking pictures and measurements of the outside stairs to the 2nd floor unit. 

@Won Lee, I would measure temperature of the cold air coming out of the ducts.

I can offer advice on: All things online marketing and measurement.