So the normal calculation is Appraised value * 70/80% - existing mortgage/leins = HELOC amount.

Hi, BPersI am in the middle of applying for HELOC on my primary home and the bank sent an appraiser to appraise the value of the house.

Here is my question: My father purchased a home with cash in San Antonio Tx about 5 years ago for 240k, the house recently appraised for 320K.

Rehab minor cosmetic, using private money for down payment and rehab.Rent at new appraised rateRefinance, if cash out is an optionRefinance cashes out original seller too.Use cash out to pay lender backFind a tenant/buyer willing to pay mortgage = current rents, and willing to put 10% down on new appraised value.Seller finance at higher interest (wrap)Collect cash flow, no landlording responsibilities, add the leftover cash out to the buyers down payment = new investment and repeat.

With it being a small multifamily unit I am having a difficult time finding comps to use as comparison for the appraisal. 

I noticed very weird things on the property appraiser with quit claim deeds and multi claim deeds, which I do not understand.

If you're wondering if the offer is a fair market price, consider having an appraisal done. 

SF can be used,  they are used all the time for appraisals when not enough MFR have sold recently.

It appraises at 140k.

There are foreclosure fees, title fees, appraisal/inspection fees, late fees, publishing fees, etc.