Rental 1 (purchased with HELOC): Worth $210k
Rental 2 (purchased with HELOC): Worth $100k
Rental 3 (purchased with HELOC): Worth $100k
If your worth numbers lined up with bank assessments, you should be able to get bank loans of all three to pay off the HELOC plus some since your HELOC debt to rental value is 67.6%. The rates and terms on residential loans will be better than a commercial loan and should be your first preference.
Fannie allows up to 75% LTV on cash out refis on SFH investment properties (https://www.fanniemae.com/content/eligibility_information/eligibility-matrix-063015.pdf
). So, in theory you will be able to cash out an additional $30K on 75% LTV individual mortgage loans on each property. Given your price range, this may be sufficient for a down payment on a fourth property and meet Fannie reserve minimums (6 or 12 months depending on your credit score and DTI) presuming you have been already setting aside 20% rent on each property for CapEx and maintenance. This is also presuming that your day job(s) plus 75% of the gross rental income would give an acceptable DTI for the underwriter.
However, I am concerned about the ability of the properties to support full mortgages given your sole comment about them supporting the interest payments. What are the rents like?