Hello, I recently had a new heat pump installed with a 20kw heat strip for auxiliary heat. Needless to say, I am not impressed with the performance of this setup. I am considering getting a high efficiency gas furnace to use as my aux heat. I've noticed that I can get a nice Goodman unit on ebay for far cheaper than any hvac place will charge me. I am interested in going this route and paying someone to install the furnace for me. I had a few questions first though: -The heat pump/ac is 3 ton and I have a 3ton coil/air handler. Will any gas furnace be compatible with this? Reason I am asking is the 20kw heat strip can't keep up when it gets really cold, so I want to get a slightly higher output gas furnace (probably 90,000 BTU). -for this application I want to vent this out the side of the house. My chimney is junk and the furnace is in a sealed crawl space. From my understanding this is doable if I get the 90%+ efficiency models, correct? -are there any other parts I will need to get besides the furnace, fossil fuel kit, LP conversion kit, and new thermostat? thanks!