Hey, welcome back. I may have missed it but I don't recall a post with your entire situation so I'll do best to answer.So, to summarize what I've learned from this thread, and elsewhere:
/1/ to get the full $5k rebates, I'll need to completely get rid of my 10 year old gas furnace, and completely replace it with a heat pump. certainly $20k+, and though while I will get sufficient heating in the Seattle winter, it will be slower, as the air comes out at cooler temps... I suspect wife wont be happy. I have also learned there will be little to no energy cost savings.
/2/ With an AC heat pump add on, even if I get the more efficient heat pump that at first appears to be at the SEER level to get the federal tax credit, it is unlikely to actually qualify for the tax credit unless I also replace the furnace (blower only?)
/3/ with AC heat pump, upstairs (master bedroom all that matters 98% of the time) will likely be 5F warmer than downstairs, and not as cool as my inelegant "portable" AC gets it now.
/4/ downstairs (at least areas we use) is already adequately cooled by a large traditional window AC, in one of the few windows in the house where it fits.
So... choice is to spend $12k+, and higher annual energy bills, to add central AC, that is much simpler, and more elegant, but doesnt provide substantially better cooling. Do I make the Boglehead choice? or the happy wife choice?
1 - I assume the $5k is Seattle/Washington specific rebates. The federal heat pump rebate is $2k.
The last system I helped someone with, last month, was $11k, replacing full HVAC system, including existing AC with an 18 SEER inverter driven heat pump (aka not lowest end), before any rebates. Since you do not currently have central AC it'll cost a bit more to prep outside and run lines.
Cooler output temperatures is accurate but irrelevant, it'll still be quite comfortable with warm air coming out of the vents (20 years ago was a different story).
Cost savings cannot be answered without more information including energy costs for both electricity and gas, but a heat pump will generally save you money. But air sealing and insulation should be a higher priority.
2 - Not exactly following - but replacing an AC unit with a heat pump that is eligible (and many/most vendor websites tell you if it is) will qualify for the FEDERAL tax credit regardless of furnace. As #1, I'm assuming the $5k is local credits which I don't know the rules for.
3 - Some ways to mitigate this were answered above, but at the most basic, regardless of type of system, yes, a higher floor will be warmer than a lower floor when using one central unit. If your goal is one room cooled, get a mini split unit installed for just that room, not central AC.
4 - ok.
Summary -
My advice, based on what this adds to the information, is that since you do not currently have central cooling, and are debating adding it, skip the AC vs. heat pump discussion because everything you are posting says you don't want central cooling.
Instead, you should get 1-2 heat pump mini split units (or single multi split), 1 to cover primary bedroom and 1 to cover the area of downstairs you use and skip central AC (via heat pump). It'll cost less, use less energy (because it is cooling less space), and give you the comfort you are looking for. There are even portable (window vented) heat pump units that could be more efficient than what you have now.
Statistics: Posted by Scotttheking — Thu Mar 28, 2024 12:02 pm — Replies 27 — Views 1708