No need to pay big bucks for this. 

Why pay off the mortgage early? 

Tenant covenants and agrees to pay interest at the maximum lawful rate or eighteen percent (18%) interest, whichever is less, compounded annually, on all unpaid Rent, damages, and other amounts owed by Tenant, excluding late fees, from that date of Landlord’s final accounting until such time Tenant pays all such outstanding amounts.

We typically pay somewhere in the range of $3500 for a new, basic furnance, including install, if there are no other modifications to the system required.  

It's likely they’re using this as an excuse to avoid paying rent, and there’s a good chance they didn’t pay the previous manager either.

. $1300/month, tenant pays all utilities. 4 bedroom one is vacant.

Suggesting to them buying their house for a wholesale range offer or lower dependent on the extent of the rehab, then having a contract in place that gives them a percentage of the profit to help get them back on their feet, paying off debts etc.

I cannot sell a house with broken equipment, and I cannot pay someone for breaking what they were suppose to install. 

I LOVED getting a loan through DR Horton on a DR Horton build, that I had to pay for a DR Horton appraisal.

We will be paying nearly $50,000/year in property insurance.