Advice using equity to grow residential portfolio

[Javier Emilio Tirado]

Hi BiggerPockets friends, 

My wife and I are looking for some advice on moving forward and growing a residential portfolio using our current equity. 

First, I would like to share some little background on our "real estate experience" about 5 years ago my wife was gifted a fairly large/valuable home by her parents. 3 years ago we started renting a room on Airbnb and it went fairly well so we began adding more and more rooms until we either had 6 individual rooms rented or rented the whole house as a vacation rental. Even though this was not the intention of the gift it turned into what is now our business and our passion. 

In those 3 years, we have also rented 2 additional properties which we use for vacation rental. 

And we bought 1 property through an FHA loan and invested in the repairs of the home with our own money/savings. (which we also use for vacation rentals)

Now I've been reading and watching youtube videos on how to proceed from here and this is where we are looking for advice as after all we are newbies. 

We probably have around 1M-1.5M equity in the gifted home and around 150K in the FHA loan home.

How do we best use this equity to acquire new properties? We are a bit adamant about placing a mortgage on our "safe" (paid off) home. For which my train of thinking is to get a HELOC on the home ----> Buy new property cash ----> refinance new property----> pay off HELOC = house safe without debt again. Now I'm a visual guy so it has been hard finding an example of this and how the numbers would actually look and I can't really wrap my head around it. For example, I pay 100% cash + repairs but I can only get 80% refinanced and can't fully pay off the HELOC loan or because of the repairs the value of the home goes up enough that 80% covers the whole HELOC loan. We are basically looking for a way to cover everything without touching our money. A visual example would be great XD.

I apologize if the explanation is a little rough around the edges. We are looking to start growing and any advice would be very helpful.

Thank you for your time, 

-Javi