Now 3yrs later, the son of the deceased sister who had power of attorney for his mother (she left no will just a supposed request on her death bed that the house be sold) wants to extract the equity out of the house.

Working with people like this has shown me the power of real estate.

I still have baseboard heating so even though the ski season would get good utilization, the economics don't work with the inefficient heating setup.French Broad (local power co) is running a program to sell ductless split unit heat pumps at cost and will finance them.  

You want to check out this podcast: Bill Powers uses the lease option strategy for his investing.https://www.biggerpockets.com/renewsblog/2016/07/28/bp-podcast-185-rent-to-own-increase-cash-flow-maximize-equity-bill-powers/

Knowledge is power and my power is free.

You can always ask, and more power to you if that works out - just not likely something most would consider. 

If so what do the contractors do about powering their tools on the construction site?

Consider long term costs.Central unit(s) belong to you, are maintained by you, and you need to provide power and pay that bill.Window units, even if you provide them, at least place the operation power usage on the tenant.If you clearly note in the rental agreement that "the window units are a gift to the tenant", then maintenance is off-load too.Frequently, the long term costs have a larger impact to your PnL than the cash outlay for the equipment itself.

@Amanda Moore I'm hoping this post gave you some direction and certainly hope you are following up with @Dean Letfus with that offer he just gave to assist... gotta love BP, shows the power right there

But also note the merits and the power of equity.