Hi @Rahsheen Slaughter, there are a couple of risks to watch out for.
1. Rates rising. The rates rising will cause your HELOC payments to increase since HELOCs are ARMs. Additionally, the refinance rate will be higher than the rate to purchase upfront. You could continue holding the HELOC and paying the IO payment until rates drop again but if you want to free up your HELOC to purchase other properties or use it for other purposes, you cannot.
2. Property value deflation. If the property value decreases from the time you purchase to the time you were planning to refinance, you may not get enough equity from the refinance to pay off the HELOC.
3. No principal buydown. Most HELOCs are interest-only so there will be no principal buydown from the time you purchase to the time you refi.
4. Higher monthly payments. Since you are borrowing cash to purchase a home, you will need to pay a certain amount per month for the IO payments on top of hard money, renovations, utilities, etc.
With that being utilizing HELOCs will allow you to grow your rental portfolio much quicker so it can be a great strategy as long as you account for the above risks.
Hope this helps! Let me know if I can be of any assistance.