Easy question first, you are not allowed any sweat equity. That is, you should not have included anything, for your labor, when you increased the cost basis in 2004.
Second, you do not need to adjust the cost of your new (I assume 2019) heat pump. You may set the entire cost up for depreciation or if you qualify (probably not) write it off. See https://ttlc.intuit.com/community/state-taxes/discussion/de-minimis-safe-harbor-election/00/39814?ju...
Third, you may be able to do a partial disposition of the old heat pump (write off the un-depreciated part). That involves retroactively separating the asset from the total cost of the house. See links below for a full discussion.
You may want to consider having your taxes one professionally this year.
https://www.thebalance.com/partial-dispositions-3192873
https://evergreensmallbusiness.com/partial-dispositions-and-the-new-tangible-property-regulations/
https://www.irs.gov/businesses/small-businesses-self-employed/tangible-property-final-regulations
