Using HELOC to Buy Outright? Then Refi?

[Alex Todd]

Total newbie here but have been reading from afar about how to leverage/extract equity from a primary residence using a HELOC and want to validate an approach/idea/though to see if I'm following this properly.

If I was to take a HELOC out to buy a SFR outright(~$100k purchase) and then re-finance after 6mo/1yr to fixed 30yr rate and get an 80% LTV, I would essentially "get back" $80k, pay off principle of HELOC directly, and return the "used" HELOC value to $20k. Is that feasible/accurate? Also, is that the right way to look at leveraging a HELOC when our goal is Buy and Hold, long term strategy?

Note " I'd then combine the HELOC interest only monthly payment with new mortgage to get a total monthly cost when doing property evaluations."

If the above is feasible and accurate, knowing now that I still have to pay off $20k of HELOC...why wouldn't I use the same $20k HELOC as down payment for the same house and limit exposure/closing costs/time of refinancing? Or use say $60k and purchase 3 homes?

Thank you in advance for the help/guidance!