Also, is this a high efficiency HVAC system?

Just the way I have learned to do it efficiently. 

Some questions to ask (from @David Greene’s book “Long Distance Real Estate Investing”What experience they have managing rentals personally, how many doors their company manages, how long they have been in business, and what they feel their company’s strengths are, how they collect rent, how they enforce late fees, what systems they have in place to make things efficient, and how long they have worked for their current company.I hope this helps. 

It's much more efficient this way.

I let them go on for months, costing me thousands.But I learned and handle things much more efficiently these days. 

Maybe you will be better at estimating, or more efficient with the work.

Things that increase or decrease your rent are things that cause the utilities to go up or down, such as size, number of shared walls, utilities, appliances, type of heat, any energy efficiency features, etc.

A Solo 401(k) plan is exempt from UDFI pursuant to Internal Revenue Code Section 514(c)(9).With the UBTI tax rates at approximately 40% for 2017, the Solo 401(k) Plan offers real estate investors looking to use nonrecourse leverage in a transaction with a tax efficient solution."

Not to be discouraging but being practical on finding a most efficient spot to spend your resources. 

So step 1 would be to define your investment criteria.Step 2 would be to start filtering on those large popular sites and finding opportunities that meet your criteria.Step 3 is to analyze those opportunities and become efficient at understanding what a good deal is and what a bad deal is.Step 4 is after building knowledge analyzing deals, to reach out to brokers in your target market, communicate your investment criteria and build rapport.Step 5 is to receive leads from those brokers, underwrite those leads and make offers at a price that meets your investment criteria while communicating with the broker why certain leads do not meet your investment criteria in order to get more targeted leads in the future.If you do these steps consistently, I believe you will have a good chance of acquiring a great property that meets your goals!