Okay, I have time for a longer post now. It's mostly my rambling train of thought, so feel free to ask about anything I might have left out.
I installed the heat pump in Denver last summer with the Denver specific rebates. I know the structure has changed a bit with the IRA, but the total economic value should be roughly comparable.
I'm overall very happy with the end result, but I had some issues with the subcontractors and communication throughout the process. I'm happy to PM you contractor-specific details, as I'd still mostly recommend the company I used, but with some caveats I'd prefer not to post on the open internet.
I also admit I'm biased on the topic. While XCEL is a pretty good utility when it comes to converting to renewables, their lobbying for natural gas interests makes them one of the biggest hindrances to doing anything about climate change in Colorado. They're a scummy company, and I believe finding ways to cut a gas meter is a public service.
First off, you want to do a home energy audit with a blower door test. XCEL subsidizes these if you use qualifying contractors. Helio Home (which I mentioned in my prior post) does these. Get multiple quotes for any recommended insulation work, as I hear the companies that do the audits tend to quote high for insulation. XCELs participating contractors are here:
https://co.my.xcelenergy.com/s/residential/home-services/home-energy-auditOne recommendation for an insulation quote is "Colorado Insulation & Whole House Fans" (
https://www.coloradoinsulationandfans.com/). My FIL used them after getting multiple quotes. He had a good experience, and I used them to install a whole house fan that I'm happy with.
You want to go with an installer that specializes in heat pumps. A lot of the general HVAC contractors don't want to learn heat-pumps and try to sell against them. And some of the contractors jumping in the market don't know what they're doing yet.
My contractor recommended Mitsubishi units, and I think they're a great fit for Colorado, and your situation in particular. I like how quiet they are. They're also variable speed units, which means they are designed to run for longer periods at lower power. It's more noticeable in the summer, but it did help mitigate a temperature difference in our upstairs. It narrowed the upstairs temperature differential from roughly 5 degrees to 2-3 degrees. So it wasn't a cure-all, but it did help. A good installer will give you some other options for your basement heating problem as well. One option with heat pumps is having a single outdoor unit power multiple indoor units. For example, you can have one outdoor unit power an air handler plus a mini-split in the basement. We did this for our upstairs. Zoning might be an option too. Find a professional that gives you a good feeling about their ability to solve this.
This will be a pricey project. Don't be surprised by prices of $10K, even after incentives. I think it's worth it, but it is a big money commitment.