Did your weather suddenly turn colder 2-3 weeks ago? If so, the night time temperature in your condo may be falling further that it was before. Most modern automatic thermostats employ an anticipation feature. If you program the thermostat to warm up the house to 70 degrees at 7:00 AM, it will cycle on and off before that time so that by 7:00 AM, the temperature is at 70 degrees. As the weather gets colder, the anticipation feature needs to kick in earlier and earlier so that your desired temperature is reached by the time you've programmed. Many automatic thermostats will allow you to turn off the anticipation feature. Your thermostat owner's manual will tell you how. Once you've turned anticipation feature off, the heat won't come on until the time you've programmed.

You need to get a technician over to see if your heat exchanger is cracked. That could be where the noise is coming from. Or it could be coming from something in the duct work that is loose, but a tech could trace down the noise for you.

What are your gas and peak electric rates? If you generate more electricity than you can use are you able to sell it back to the electric utility? It may be cheaper to heat your home with gas furnace than a heat pump. You should determine that first. You should also get quotes on the equivalent AC condenser to get an idea how much more the heat pump will cost at installation. Your furnace is a single stage. Installing a multiple stage condenser is expensive and provide little benefit. A 16 SEER single stage Trance AC or heat pump would make the most sense.

Thanks, Mike & Tigerdunes: I've been a builder for over 30 years so I tend to pay very close attention to the little things happening in my home as I'm the guy who probably installed it and has to fix it if it breaks. I had a Honeywell Wifi thermostat that was terribly unreliable in terms of its Wifi connectivity and lack of today's available features. I did not want one of the new Internet based DIY thermostats like Ecobee or Nest because they get their temp from the Internet, a temp that is always several degrees differant from my home. I wanted a hardwired outdoor sensor. So, I installed one and a Venstar T7850 Wifi thermostat that appears to be rock solid, versatile, easy to program and the connectivity is flawless. My brother is a commercial builder and uses them exclusively in his buildings with great success. It provided all sorts of usage data on a minute by minute basis if desired. It even has an installation test mode that checks your wiring and turns different components on and off to confirm your setup, which I think is brilliant. That said, I feel good about my wiring and setup. I can run 'Emergency Heat' with my inverter/generator during a power-loss, and everything else seems to work fine. My changeover point is set to 33 degrees which is determined by the hardwired 10 ohm outdoor sensor as it should be. My only concern is the one I mentioned in my initial post: I call for 5 degrees of heat, the heat pump comes on for a couple of minutes, then the furnace lights up due to the 5 degree call, and my heat pump does not shut down (or it doesn't seem to). It might be that it would shut down in a matter of minutes or might just be winding down in some cool-off mode. As I said, I am afraid to let it run just to see what happens because something bad might happen... like creating an over pressure situation and blowing a refrigerant line. I wish I could find out if this is not out of the ordinary for a heat pump but thus far nobody can tell me definitively as there are different variables, which is understandable. It's just hard to get anyone out here during this virus and the drive-time alone adds 100's of dollars before anything is even gets looked at. Sorry this got so long winded.