I changed my home from oil heat to a heat pump system, and it is FANTASTIC. The heat pump system costs less to run than the FAN on the old oil-based system!! The savings are incredible. And, added bonus, the heat pump is both a heating and cooling system. And since Seattle now regularly has weather over 90 degrees in the summer (this NEVER used to happen), the cool air is a real blessing. If you can go for a heat pump, do it. No regrets here.
What make and model did you get? I find it really hard to find details on heat pumps, especially whether they'll be effective in a climate that can get really cold. It seems like they're being marketed in the southern US but not northern where I am. My furnace and A/C are both up for replacement. Now would be the time.
Instead of selecting the system I wanted, I selected the company I wanted to use. They came in, checked our needs, assessed the airflow and square footage of our house, and then they made the recommendations for the system to buy. We wound up with the Daikin heat pump in the attic with ducting into the upstairs bedrooms and bathrooms, and then two split-mini units in the common areas (living room upstairs and rec room downstairs) to allow us specific zone controls across the bedrooms and living areas. Heat pumps are not often used in extreme climates, simply because they use the ambient air temperature, and add to or subtract from it. There are various (unsourced) claims that heat pumps are only good for a 40-degree change from the ambient temp. So if it is -20 outside, the heat pump is only going to get you up to 20 degrees inside. Or if it 120 outside, it's only going to get you down to 80 indoors. This is why I'd find a reputable local HVAC contractor and have them suggest the right solution for your location, home, and needs. There are a lot of variables that you can spend a long time learning... or just work with a pro who already knows this shit, and knows what works and what doesn't in your area. (And who has a good reputation for long-term service.)
...and they might have old stock from a mis-order sitting in the warehouse that they can make fit. We have been told by a number of HVAC companies that the furnace we have is twice the size we need, and that we paid basically salvage prices for it. On the plus side? It fuckin' moves some air. On the minus side? I know I need to change the filter when it stops oilcanning the plenum. whump WHUMP
Read some of the articles at https://www.energyvanguard.com/blog/ . A lot of the math details are missing but the concepts are well explained
We have a Lennox. It’s ok but not perfect. The pump has a tendency to freeze a lot of ice up on 40 degrees high humidity days and stops being effective around 20 degrees. You need good wide large ducts on your pump or it won’t work well. That’s key the heat pump needs to circulate a lot of air as delta t is small so you need to push high volume to compensate.