In a tankless unit the minerals will plate-out on the inside of the heat exchanger piping so they have to removed with acid.As with most things;  the "short lifespan"  of tankless water heaters is always due to poor / no maintenance.  

Maybe you guys can take a look and possibly throw out a few ideas.I can't offer my own real estate thoughts in exchange, by the way.

I am in the middle of a 1031 exchange and will be buying another 4 or 5 properties within the next 3 months. 

But @William E. rightly recognizes that a unique opportunity has come your way through that walk through couple.Normally a 1031 exchange on this project would be difficult to defend because the timing and process would look awfully like a fix n flip and those do not qualify for 1031 treatment.

I'm currently in a 1031 exchange.

Otherwise you can simply state that his daughter is an adult and he has no legal right to interfere as the contract does not involve him if he tries to challenge you.It's easy to get wrapped up in the personal side of this exchange, but don't let that change your approach.

However, I knew that was happening well ahead of time and agreed to it, in exchange for not paying the seller back the pro-rated property taxes. 

Not saying that will happen, but its easier to be right on the front end.Also, if you're flipping frequently, I highly recommend discussing the rules of a 1031 exchange and this can be a great tool to deferring taxes on gains associated to real estate.While I do go on record that I am a CPA, I do not specialize in real estate tax transactions as my background is audit (not tax), it's important you speak with a real estate tax accountant to ensure your best interest are met.I hope this was helpful, there are plenty more GL accounts to include and PM me if you have more questions.

I can 10-31 exchange them for more properties thanks to the appreciation though, so that's a plus.I have all my money in real estate at this point, roughly 500K.

You can also download your State's wage rate, which will give you a pretty good idea of what hourly wage you should be paying for each trade, regardless of their union or non-union status.Don't play the "I can get a better deal with so&so game", it never leads to a WIN-WIN.