Re: Crazy to buy a used heat pump?
At our old house we had an AquaCal Heat pump. I was really happy with the performance and the cost of operation compared to gas. But, during this time understand that our electric was real time pricing, updated per the hour. This can be risky, but it can pay off too. There were times during the evening that rates were under $.02 per kWh...it wasn't uncommon to have negative rates either. You take advantage of these scenarios if it warm and humid enough. But, my point is be sure you have decent electricity rates if you're going with a heat pump.
We actually did buy ours used off of Craigslist and got lucky with a good unit. It's certainly a risk. Myself, having had a 100k+BTU heat pump on a 10,500 gallon pool...I would not go smaller.
Dan