If you plan on eventually selling, central air would add a significant value increase, so you may consider if that's the case. 

The two-family property now has better curb appeal and the rental units are much more desirable, which has helped me increase my rental income.

@Paul Whitney Detroit property values increased over 20% in 2024:https://detroitmi.gov/news/detroit-home-values-increased-ave...https://www.cbsnews.com/detroit/news/detroit-home-prices-amo...https://www.detroitnews.com/story/news/local/detroit-city/20...DM us if you'd like more info...

Because I rent 4 bedrooms house, it's more conducive to large gatherings and parties.Another issue and please tell me if this is normal that when people book for 5 people they usually have at least 10 or 15 additional guests. 

Loss of Use / Loss of Rents: Normally, there is a 20% included limit.

When they started screwing with us last week about appraisals and then having to give them an ‘after reno’ price for the house when they had no idea what we were doing the house to increase its value, I did mention to the partners I thought we’d been scammed.

All of these small details can increase value and bring buyers for zero dollars. 

Assuming you go the HELOC route, another option to reduce your costs assuming you have decent credit is to look at credit card balance transfer promotions.Back in 2003-2004 I had HELOCs on my investment properties and interest rates were increasing.

One of the best ways to start investing imo, especially for young people who can be flexible on location, unit size, etc.3- look for properties with value add- renovate and/or reconfiguring units, maybe adding an ADU in basement or garage conversion, upside in rent increases via tenant turnover due to natural attrition, buy outs, etc.

Just not sure how often they are getting rented